Patent Application
20230230775
The invention encompasses energy storage devices such as capacitors, comprising a metal-ion organic complex component. Processes for preparing the devices and methods of use thereof are provided as well. The electrochromic property of devices of this invention is utilized to indicate charge/discharge level of the device.
Electrochromic (EC) materials have distinct ability to alter their optical transparency in response to application of voltage. This property is particularly useful in smart windows, electrochromic windows, smart mirrors, optical filters, frequency doubling devices, spatial light modulators, pulse shapers, displays, signs, plastic electronics, lenses, sensors, and numerous other devices.
An interesting class of EC materials is metal-coordinated organic complexes where a metal ion is coordinately bonded to an organic molecule (a ligand). In order to obtain high-performance films of EC materials, the materials should be coated on a conducting substrate in a uniform manner. Film composition, film thickness, film density and film uniformity are properties that can greatly affect the EC performance of the material film. Such properties are important for various applications. EC applications include electronic displays systems such as color filter displays, monitors, TVs. Optoelectronics systems such as optical switches for optical telecommunication and optical/laser systems (e.g. for machining, medical treatments, army/military/space), construction materials products such as smart windows and light filtering windows, and products for the auto industry such as tintable reflective surfaces (e.g. car mirrors).
In view of the promising EC properties of metal-coordinated organic complexes, there exist a need to find a process for preparing high-performance EC materials and films comprising such complexes.
Further, the growing demand for light-weight and miniaturization of traditional consumer electronics, has accelerated the research and development of new functional devices. Replacing conventional elements of silicon and metal-based circuits and devices with light-weight, high-performance molecular or polymeric materials is highly desirable. Numerous functional organic materials have been developed to produce solar cells, organic field-effect transistors, spatial light modulators, organic light-emitting diodes, and electrochromic windows. Despite the vast arsenal of materials available, the formation of layered, stable architectures remains a challenging task. For example, interfacial contacts between different components of a layered device can be affected by de-wetting. It was shown that the performance and stability of organic light-emitting diodes can be enhanced using covalently bound monolayers on the surfaces of metal-oxide electrodes. Although the introduction of several new materials has led to real-world applications, to date, the full potential of molecular- and polymer-based devices has not been unlocked. This is partly because of upscaling-related issues and cost, but also because of stability and device integration which hamper large-scale utilization. Combining different functions in organic devices and coupling such devices with conventional technologies is still in its infancy. In this respect, one important target in energy devices is the combination of energy production with additional useful functions, such as in-operando monitoring of device performance. In this aspect, the use of photovoltaics with electrochromic materials and the integration of lithium batteries with solar cells have been reported. For example, an electrochromic-photovoltaic device that can be used as self-powered smart glass has been reported. A capacitive smart window from electrochromic polymers has been demonstrated as well. The use of “stand-alone” electrochromic materials is attractive for applications related to smart windows and mirrors. The combination of such coatings with electronic devices allows a read-out of device operation by the naked eye in real time. Therefore, there is a need for advanced electronic devices that may utilize electrochromic properties of their components.
In one embodiment, this invention provides energy storage devices comprising metal-ion coordinated organic complexes. Energy storage devices of this invention include electrodes, capacitors, supercapacitors, hybrid supercapacitors and batteries. The metal-ion coordinated organic complex functions as a redox active material and is provided on at least one electrode in devices of this invention. Further and in some embodiments, the metal-ion organic complex material is electrochromic. The color or the absorption spectrum of the material changes in accordance with the oxidation/reduction state of the metal ions in the material. According to this aspect and in one embodiment, the charge/discharge level of the device can be monitored by the color/optical spectrum change of the metal-organic material in the device. Further, in order to obtain efficient hybrid supercapacitors, a unique composite capacitive electrode has been developed as described herein below.
One embodiment of this invention provides an integrated electrochromic-hybrid supercapacitor (EHSC). The device's operation (charging-discharging) is indicated by optical changes. For example, in one embodiment, the device or a portion thereof is transparent when fully charged and is colored when fully discharged. Accordingly, upon charging of the device, a transition from colored to transparent is observed. The heart of the device is an electrochromic metallo-organic layer that functions as both the battery-type electrode and as the charge optical indicator. In this electrode, the color indicates the charge. The second electrode is a capacitive electrode. In one embodiment, the other electrode (the capacitive electrode) is a layered composite of multi-walled carbon nanotubes (MWCNTs) and a conductive polymer (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, PEDOT:PSS). In some embodiments, devices of this invention operate under low potentials (for example, −0.6 V to 2 V), display high energy density and high power density (for example ˜2.2 Wh·kg−1 and ˜2529 W·kg−1 respectively), high coulomb efficiency (e.g. 99%), short charging time (e.g. ˜2 s), and charge retention (V1/2) of e.g. ˜60 min. Stability, both in color and energy, for more than 1000 consecutive charging-discharging cycles was demonstrated for devices of this invention in one embodiment. No significant changes in device temperature were indicated under the operating conditions in some embodiments. In one embodiment, the EHSC was wired with a conventional circuit board to be charged and subsequently to discharge and operate a diode.
In one embodiment, this invention encompasses methods of depositing multiple layers of electrochromic materials onto a substrate thereby creating a multilayered EC assembly or an EC film. The invention also encompasses multilayered electrochromic materials. Further, this invention provides uses for the electrochromic materials. In one embodiment, this invention provides the use of electrochromic materials of this invention in supercapacitors. The invention also provides a supercapacitor comprising an electrochromic material of this invention. According to this aspect and in one embodiment, one electrode of the supercapacitor comprises an electrochromic material of this invention. In one embodiment, the supercapacitor or a portion thereof changes color in response to a change in the charging/discharging state of the capacitor. According to this aspect and in one embodiment, the electrochromic material in the capacitor changes color in response to the degree of charging/discharging of the capacitor. In one embodiment, the charging/discharging of the supercapacitor involves oxidation/reduction of the metal ions in the electrochromic material. The change in oxidation state is accompanied by change in color of the material in one embodiment.
According to this aspect and in one embodiment, the device color is an indication of the level of charging of the device. Optical indication of charging level is a useful property of the device in some embodiments.
In one embodiment, this invention provides a capacitor comprising:
wherein said electrochromic film comprising metal ion-coordinated organic complex.
In one embodiment, the metal ion is Fe ion. In one embodiment, the second electrode comprising carbon. In one embodiment, the carbon comprises carbon nanotubes. In one embodiment, the carbon nanotubes are multi-walled carbon nanotubes. In one embodiment, the second electrode comprising a polymer. In one embodiment, the polymer comprises PEDOT and PSS. In one embodiment, the electrodes comprise a conductive material. In one embodiment, the electrodes comprise conductive oxide. In one embodiment, the conductive oxide is selected from ITO and FTO. In one embodiment, the conductive oxide is attached to silicon oxide. In one embodiment, the silicon oxide is a substrate. In one embodiment, the capacitor is arranged in layers as follows:
In one embodiment, the first substrate, the second substrate or a combination thereof is selected from the group consisting of silicon dioxide and organic polymers. In one embodiment, the first substrate, the second substrate or a combination thereof comprises a material selected from glass, quartz, polyethylene terephthalate, PDMS or any combination thereof. In one embodiment, the first substrate, the second substrate or a combination thereof comprises aluminum oxide. In one embodiment, the capacitor is a supercapacitor.
In one embodiment, the capacitor is a hybrid capacitor, wherein the first electrode is a battery-type electrode and the second electrode is a capacitive electrode. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is having a transmittance difference between the oxidized and the reduced states of 10% and higher. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is having a transmittance difference between the oxidized and the reduced states of 64% and higher. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 40% of its maximum contrast ratio after 50 switching cycles between oxidized and reduced states. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 54% of its maximum contrast ratio after 1000 switching cycles between oxidized and reduced states. In one embodiment, the capacitor comprising:
In one embodiment, the capacitive material layer comprises a polymer or carbon or a combination thereof. In one embodiment, the capacitive material layer comprises a layer of polymer attached to a layer comprising carbon. In one embodiment, the first conductive oxide and the second conductive oxide, each independently comprises an electrical contact capable of connecting said conductive oxides independently to an external device/circuit. In one embodiment, the metal ion-coordinated organic complex comprises a metal-ion polypyridyl complex. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, comprises from 2 to 80 layers of said metal ion-coordinated organic complex, said layers are linked to each other by a metal linker. In one embodiment, the metal ion in the metal linker is at least one metal ion selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y. In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex represented by Formula I as described herein below. In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex represented by Formula II as described herein below. In one embodiment, formula II below is represented for an organic complex comprising Fe (iron) as the metal ion. However, in other embodiments of this invention, the Fe ion in formula II is replaced by any other metal ion that can be coordinated by the ligands of formula II. All such metal-ion organic complexes are included in embodiments of this invention.
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex, said pyridyl complex is selected from 1DB, 2DB, 1SB, 2SB, 1TB, 2TB or any combination thereof wherein M=Fe, the pyridyl complex is represented by the corresponding formulas illustrated herein below. In one embodiment, the metal ion-coordinated organic complex comprises a mixture of the above-mentioned formulas, or a combination of these formulas with molecules comprising different metal centers or ligands (according to the general formulas I and II). In one embodiment, the polypyridyl complex is a mixture of polypyridyl complexes.
In one embodiment, this invention provides a method of using the capacitor described herein above, the method comprising:
In one embodiment, the color change is an indication of the charging/discharging level of said capacitor. In one embodiment, the capacitor is at a bleached state when charged and it is in a colored state when discharged. In one embodiment, the colored state is the more molecular-stable state, and the bleached state requires applied potential. In one embodiment, the color change is detected by an optical detector. In one embodiment, the color change is detected by the eye. In one embodiment, the device or a system comprising the device, further comprises a light source for detecting the color change of the device or for enhanced detection of the color change.
In one embodiment, this invention provides a device comprising:
In one embodiment, the electrical contact(s) comprise open/close switches or other open/close mechanism, to allow or to prevent electrical current from flowing through the contact(s). In one embodiment, the device further comprising an optical detector. In one embodiment, the device further comprising a light source. In one embodiment, the device further comprising a processor for receiving input signal from the optical detector and to provide control signal to said device. In one embodiment, the control comprising at least one of: initiate charging, halt charging, initiate discharging, halt discharging.
One embodiment of the invention encompasses a method for making an EC material (or an EC film) comprising providing a substrate, applying at least one metal linker, applying at least one metal-coordinated organic complex to form a layer, and repeating the applying steps to obtain a multiple layer EC material.
In one embodiment, the metal-organic complex comprises at least one functional group, said functional group capable of binding to said metal linker. In one embodiment, the binding comprises a coordination bond between said functional group and said metal linker. In one embodiment, the metal coordinated organic complex is a polypyridyl complex.
In one embodiment, the applying steps comprise deposition techniques such as roll-to-roll, spin coating, dip coating, spray coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) or combinations thereof. In one embodiment, the polypyridyl complex comprises one isomer, or more isomers of the same compound. In one embodiment, the polypyridyl complex comprises a mixture of isomers. In one embodiment, the polypyridyl complex comprises any mixture of isomers of the same compound. In one embodiment, the isomers are enantiomers. In one embodiment, the polypyridyl complex comprises one or two enantiomers of the same compound. In one embodiment, the polypyridyl complex comprises a mixture of said one or two enantiomers. In one embodiment, the enantiomer mixture is a racemic mixture. In one embodiment, the applying step(s) comprise spin coating.
According to this aspect and in one embodiment, this invention encompasses a method for making an EC material, the method comprising providing a substrate, applying at least one metal linker by spin coating, applying at least one polypyridyl complex by spin coating to form a layer, and repeating the applying steps to obtain a multiple layer EC material. In one embodiment of the invention the spin coating step to apply the metal linker has a first spin rate and a first spin time. In one embodiment of the invention the first spin rate is from about 100 rpm to about 2000 rpm. In one embodiment of the invention the first spin time is from about 0.3 sec to about 60 sec. In one embodiment of the invention, the spin coating step to apply the metal linker has a second spin rate and a second spin time. In one embodiment of the invention the second spin rate is from about 200 rpm to about 3000 rpm. In one embodiment of the invention the second spin time is ranging between 1 second to 120 seconds. In one embodiment, the spin rate(s) and spin time(s) used to apply the metal ion organic complex are at the same ranges as those used to apply the metal linker. In other embodiments, the spin rate(s) and spin time(s) used to apply the metal ion organic complex are different from the ranges of those used to apply the metal linker.
In one embodiment, following the metal linker application, or following the organic complex application or following both linker application and following complex application, the layer is washed and/or dried.
In one embodiment of the invention the washing solvent is selected from the group consisting of tetrahydrofuran THF, alcohols, ethers, esters, halogenated solvents, hydrocarbons, and ketones. In one embodiment of the invention both applying steps are repeated to obtain from about 1 to about 80 layers.
In one embodiment of the invention the substrate is selected from the group consisting of ITO coated polyethylene terephthalate, ITO coated glass, and FTO coated glass. In one embodiment of the invention the metal linker is selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y.
In one embodiment of the invention, the polypyridyl complex is represented by Formula I.
wherein
M is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, Ru, Os or Ir;
n is the formal oxidation state of the transition metal, wherein n is 0-6;
X is a counter ion;
m is a number ranging from 0 to 6;
R1 to R18 each independently is selected from H, halogen, —OH, —N3, —NO2, —CN, —N(R20)2, —CON(R20)2, —COOR20, —SR20, —SO3H, —CH═CH-pyridyl, —(C1-C10)alkyl, —(C2-C10)alkenyl, —(C2-C10)alkynyl, —(C1-C10)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, —OR20, —COR20, —COOR20, —OCOOR20, —OCON(R20)2, —(C1-C8)alkylene-COOR20, —CN, —N(R20)2, —NO2, —SR20, —(C1-C8)alkyl, —O—(C1-C8)alkyl, —CON(R20)2, or —SO3H;
A1 to A6 each independently is a group of Formula III, i.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula I via R19
R19 each independently is selected from a covalent bond, H2C—CH2, HC═CH, C≡C, N═N, HC═N, N═CH, H2C—NH, HN—CH2, —COO—, —CONH—, —CON(OH)—, —NR20—, —Si(R20)2—, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,
Rx and Ry each independently is selected from H, halogen, —OH, —N3, —NO2, —CN, —N(R20)2, —CON(R20)2, —COOR20, —SR20, —SO3H, —CH═CH-pyridyl, —(C1-C10)alkyl, —(C2-C10)alkenyl, —(C2-C10)alkynyl, —(C1-C10)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, —OR20, —COR20, —COOR20, —OCOOR20, —OCON(R20)2, —(C1-C8)alkylene-COOR20, —CN, —N(R20)2, —NO2, —SR20, —(C1-C8)alkyl, —O—(C1-C8)alkyl, —CON(R20)2, or —SO3H; and
R20 each independently is H, (C1-C6)alkyl, or aryl.
In another embodiment of the invention, the polypyridyl complex is represented by Formula II (with M=Fe as an example):
wherein
n is the formal oxidation state of Fe, wherein n is 0-6;
X is a counter ion;
m is a number ranging from 0 to 6; R1 to R18 each independently is selected from H, halogen, —OH, —N3, —NO2, —CN, —N(R20)2, —CON(R20)2, —COOR20, —SR20, —SO3H, —CH═CH-pyridyl, —(C1-C10)alkyl, —(C2-C10)alkenyl, —(C2-C10)alkynyl, —(C1-C10)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, —OR20, —COR20, —COOR20, —OCOOR20, —OCON(R20)2, —(C1-C8)alkylene-COOR20, —CN, —N(R20)2, —NO2, —SR20, —(C1-C8)alkyl, —O—(C1-C8)alkyl, —CON(R20)2, or —SO3H;
A1, A3, and A5 each independently is a group of Formula III, i.e., a pyridine or pyridine derivative moiety, or of Formula IV, i.e., pyrimidine or pyrimidine derivative moiety, linked to the ring structure of the complex of general Formula II via R19
R19 each independently is selected from a covalent bond, H2C—CH2, cis/trans HC═CH, C≡C, N═N, HC═N, N═CH, H2C—NH, HN—CH2, —COO—, —CONH—, —CON(OH)—, —NR20—, —Si(R20)2—, an alkylene optionally interrupted by one or more heteroatoms selected from O, S, or N, phenylene, biphenylene, a peptide moiety consisting of 3 to 5 amino acid residues,
Rx and Ry each independently is selected from H, halogen, —OH, —N3, —NO2, —CN, —N(R20)2, —CON(R20)2, —COOR20, —SR20, —SO3H, —CH═CH-pyridyl, —(C1-C10)alkyl, —(C2-C10)alkenyl, —(C2-C10)alkynyl, —(C1-C10)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, —OR20, —COR20, —COOR20, —OCOOR20, —OCON(R20)2, —(C1-C8)alkylene-COOR20, —CN, —N(R20)2, —NO2, —SR20, —(C1-C8)alkyl, —O—(C1-C8)alkyl, —CON(R20)2, or —SO3H;
B1 to B3 each independently is selected from H, halogen, —OH, —N3, —NO2, —CN, —N(R20)2, —CON(R20)2, —COOR20, —SR20, —SO3H, —CH═CH-pyridyl, —(C1-C10)alkyl, —(C2-C10)alkenyl, —(C2-C10)alkynyl, —(C1-C10)alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, protected carboxyl, or protected amino, wherein the (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl may optionally be substituted with halogen, —OR20, —COR20, —COOR20, —OCOOR20, —OCON(R20)2, —(C1-C8)alkylene-COOR20, —CN, —N(R20)2, —NO2, —SR20, —(C1-C8)alkyl, —O—(C1-C8)alkyl, —CON(R20)2, or —SO3H; and
R20 each independently is H, (C1-C6)alkyl, or aryl.
According to this aspect and in one embodiment, in formula II represented herein above, instead of M=Fe, M is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, Ru, Os or Ir.
In yet another embodiment of the invention, the pyridyl complex is represented by Formulas 1 or 2, with double bonds (1DB/2DB), single bonds (1SB/2SB) and triple bonds (1TB/2TB) as shown below:
In the embodiments shown above, the charge on the counter ion is (X1−). In other embodiments, other counter ions may be used with higher negative charge such as X2−, X3−, X4−.
One embodiment of the invention encompasses substrates selected from the group consisting of ITO- or FTO-coated polyethylene terephthalate, ITO coated glass or quartz, and FTO coated glass or quartz. One embodiment of the invention encompasses an EC material made by the method of this invention having a transmittance difference between the oxidized and the reduced states of 10% and higher. In one embodiment, the EC material made by the method is able to retain at least 40% of its maximum contrast ratio after 50 switching cycles.
One embodiment of the invention encompasses a method for making an EC material comprising providing a substrate, applying at least one metal linker by spin coating, applying at least one polypyridyl complex by spin coating to form a layer, and repeating the applying steps to obtain a multiple layer EC material, wherein the step of applying the metal linker has a first spin rate, a second spin rate, a first spin time and a second spin time. In another embodiment, the step of applying the polypyridyl complex has a first spin rate, a second spin rate, a first spin time and a second spin time. In one embodiment, the metal linker is applied as a metal complex. According to this aspect and in one embodiment, the metal linker is present as a metal ion in a metal complex (for example PdCl2(PhCN)2). The metal complex comprises the metal ion and organic ligand(s), inorganic ligand(s), or a combination thereof. The metal complex is a coordination complex according to this embodiment. Such metal complex is referred to as metal linker, as metal-linker complex or metal linker coordination complex in some embodiments.
In one embodiment the metal linker is a mixture of metal linkers. In one embodiment, the polypyridyl complex is a mixture of polypyridyl complexes. In one embodiment, after the application of the metal linker, after the application of the metal-ion coordinated organic complex or after both steps, a step of washing the layer is performed. In one embodiment, after the application of the metal linker, after the application of the metal-ion coordinated organic complex or after both steps, a step of drying the layer is performed. In one embodiment, only after all the repeated application steps to obtain a multiple layer EC material have been performed, a step of washing the material or a step of drying the material or both washing and drying steps are performed. In some embodiments, no washing step is performed during or after preparation of the EC material. In one embodiment no drying step is actively performed during or after preparation of the EC material.
solvent is selected from the group consisting of THF, alcohols, ethers, esters, halogenated solvents, hydrocarbons, ketones, or a mixture thereof. In one embodiment, the concentration of said linker in said solution and the concentration of said polypyridyl complex in said solution ranges between 0.1 mM and 10 mM. In one embodiment, the EC material made by methods of this invention is having a transmittance difference between the oxidized and the reduced states of 10% and higher. In one embodiment, the EC material made by methods of this invention is having a transmittance difference between the oxidized and the reduced states of 25% and higher. In one embodiment, the EC material made by methods of this invention is having a transmittance difference between the oxidized and the reduced states of 64% and higher. In one embodiment, the EC material made by methods of this invention is able to retain at least 40% of its maximum contrast ratio after 50 switching cycles between oxidized and reduced states. In one embodiment, the EC material made by methods of this invention is able to retain at least 54% of its maximum contrast ratio after 1000 switching cycles between oxidized and reduced states. In one embodiment, the EC material made by methods of this invention is able to retain at least 90% of its maximum contrast ratio after 1000 switching cycles between oxidized and reduced states. In one embodiment, the metal linker is applied as a metal complex.
In one embodiment, this invention provides a catalyst. In one embodiment, this invention provides a catalyst for water splitting. In one embodiment, onset of water splitting can be monitored by color change of at least a portion of the device. In one embodiment, the color-change is induced by a change of the redox state of an ion within the device. In one embodiment, the catalyst is used to convert water to H2 and O2. In one embodiment, the catalyst comprises a multilayer comprising catalyst ions. In one embodiment, the catalyst ions are metal ions. In one embodiment, the metal ions are Pd ions. In one embodiment, the multilayer that functions as a catalyst for the water splitting reaction comprises an electrochromic entity. In another embodiment, the multilayer that functions as a catalyst for the water splitting reaction does not comprise an electrochromic entity. Embodiments described herein below with respect to metal-organic multilayers are applicable to embodiments of a catalyst comprising such or similar multilayers as described herein above.
In one embodiment, this invention provides a data storage device. In one embodiment, the data storage device comprises at least one redox center. In one embodiment, each redox center provides at least two states depending on its oxidation state. In one embodiment, the charge required to achieve each state using electrochemical means can be calculated. In one embodiment, each state is also characterized by a certain color. According to this aspect and in one embodiment, each state has a distinct color and requires a distinct amount of charge to be set. According to this aspect and in one embodiment, the data storage device can be set to a certain state electrochemically (e.g. by voltage application to the multilayer), and the state can be evaluated or can be read using charge calculation (electrochemically) or using optical detection. In one embodiment, when more than one redox center is included in the device such that the two centers differ in their states and/or in their color and/or in the metal ion used, the color of the device can be a combination of the colors of each redox center. Accordingly, in one embodiment, two different redox centers each having two redox states may result in a device comprising overall three different states (e.g. 2 centers reduced, 2 centers oxidized and 1 center oxidized while the other is reduced). Each overall device state is characterized by a distinct color and can be achieved using a specific amount of charge. In some embodiments, the device is based on an organic multilayer comprising metal ions, wherein at least a portion of the metal ions in the multilayer are capable of assuming more than one oxidation state. Data storage devices described herein are referred to as memory devices in some embodiments. Embodiments described herein below with respect to metal-organic multilayers are applicable to embodiments of a data storage/memory device comprising such or similar multilayers as described herein above.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
where t1 and t2 is the start and end time of the discharging process (s), respectively, I is the constant current (A), V is the voltage (v), m is the mass of the active material (kg), and Δt is the discharging time.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.
In one embodiment, this invention provides capacitors, batteries and electrodes comprising a metal-ion coordinated organic complex. In one embodiment, this invention provides capacitors, batteries and electrodes comprising an electrochromic film. In one embodiment, this invention provides an integrated electrochromic-hybrid supercapacitor (EHSC). The device's operation (charging-discharging) is indicated by optical changes in one embodiment. In one embodiment, the heart of the device is an electrochromic metallo-organic layer that functions as both the battery-type electrode and the charge optical indicator. In one embodiment, the second electrode is a capacitive electrode comprising a capacitive material. In one embodiment, the capacitive material is, or comprises, a layered composite of carbon nanotubes and a conductive polymer. The device operates under low potentials, displays high energy density and high power-density, high coulomb efficiency, and short charging time. Stability, both in color and energy, for more than 1000 consecutive charging-discharging cycles was demonstrated in one embodiment. No significant changes in device temperature were indicated under the operating conditions in one embodiment. In one embodiment the EHSC was wired with a conventional circuit board to be charged and subsequently to effectively operate a diode.
Devices of this Invention
In one embodiment this invention provides capacitors, batteries and electrodes comprising an EC film, wherein the EC film comprises a metal-ion organic complex.
In one embodiment, this invention provides a hybrid supercapacitor where the charging state of the capacitor is indicated by color. The device is based on a molecular network, that functions as both the battery-type electrode and as the charge indicator. In some embodiments, the device further comprises a layered composite of multi-walled carbon nanotubes and a conductive polymer, that functions as the capacitive (second) electrode.
In one embodiment, this invention provides a capacitor comprising:
wherein said electrochromic film comprising metal ion-coordinated organic complex.
In one embodiment, the metal ion is Fe ion. In one embodiment, the second electrode comprises carbon. In one embodiment, the carbon comprises carbon nanotubes. In one embodiment, the carbon nanotubes are multi-walled carbon nanotubes. In one embodiment, the carbon nanotubes are single-walled carbon nanotubes. In one embodiment, the second electrode comprises a polymer. In one embodiment, the second electrode comprises a conductive polymer. In one embodiment, the polymer comprises PEDOT and PSS. In one embodiment, the polymer is or comprises a conductive polymer selected from polyaniline, poly(9-vinylcarbazole) (PVK), polypyrrole (PPy). Combinations of conductive polymers can be used in embodiments of this invention. In one embodiment, the second electrode comprises any material that has capacity. MWCNT's have relatively high capacity, and accordingly are being used in some embodiments. Other useful materials with high capacity that can be used in the second electrode are conductive metal organic frameworks (MOFs) and layered materials such as graphene and MXenes. In one embodiment, the second electrode comprises two layers of capacitive materials. According to this aspect and in one embodiment, one layer comprises a conductive polymer, and the other layer comprises carbon. In one embodiment, one layer comprises PEDOT:PSS and the other layer comprises CNT's. In other embodiments, the second electrode comprises only one layer of one material (for example either polymer or carbon is present). According to this aspect and in one embodiment, if only CNT is applied on the electrode, it may come off easily. If only PEDOT:PSS is used, less energy is obtained, and the color is less stable. Therefore, in some embodiments, a two-layer structure provides a device with better stability, higher obtained energy and more stable color. In one embodiment, a layer of polymer is first attached to the conductive material and a layer comprising carbon is attached to the polymer layer. In one embodiment, a carbon-comprising material is first attached to the conductive material, and a layer of polymer is then deposited, covering the carbon material, and contacting the conductive material.
In one embodiment, the second electrode comprises a mixed layer of polymer and carbon. According to this aspect and in one embodiment, instead of one layer of polymer and another layer comprising carbon, a layer comprising a mixture of polymer and carbon is present in/on the second electrode. The carbon in such mixed layer can be in any form as described herein, for example MWCNT, SWCNT, graphene, other porous carbon material etc. In one embodiment, the second electrode comprises a porous material. In one embodiment, the second electrode comprises porous carbon. Any other material known in the art for use in capacitive electrodes may be included in the second electrode in embodiments of this invention.
In some embodiments, both PEDOT:PSS and CNT's have the same function. However, PEDOT:PSS is also used for creating better adhesion of the CNT to the FTO/ITO in some embodiments.
In one embodiment, the electrodes comprise conductive material. In one embodiment, the electrodes comprise conductive oxide. In one embodiment, the conductive oxide is selected from ITO and FTO. In one embodiment, the conductive oxide is attached to a substrate. In one embodiment, the conductive oxide is attached to silicon oxide. In one embodiment, the silicon oxide is a substrate. In one embodiment, the conductive oxide is a transparent conductive oxide. According to this aspect and in one embodiment, indication of color change is enabled or facilitated by the transparent conductive oxide layer. According to this aspect and in one embodiment, indication of color change is enabled or facilitated by optical/light transmission through the transparent conductive oxide layer. In other embodiments, the conductive material is not transparent. In one embodiment, one electrode comprises a transparent conductive material and the other electrode comprises a non-transparent conductive material. In one embodiment, both electrodes comprise a transparent conductive material. In one embodiment, both electrodes comprise a non-transparent conductive material. The embodiments described herein above fit electrodes/devices where detection of the electrochromic state is required/obtained using transmittance, or fit cases where detection of the electrochromic state is required/obtained using reflection, or fit cases where no detection of the electrochromic state is required/obtained.
In some embodiments, transparent means transparent to the eye, transparent in the visible light range. In some embodiments, transparent means transparent in the UV range, in the IR range, in the visible range or in any portion thereof, where the change of optical absorbance is detected. In some embodiments, transparent means transparent at a certain wavelength or at a certain wavelength range. In one embodiment, transparent also refer to materials having absorption that is not zero but is low enough for a change of optical signal transmitted through the material to be detected. It is to be noted that transparent or semi-transparent or low absorption of the transparent material is only required at the wavelength region(s) where the change in absorption spectra of the metal-ion organic complex is detected. The transparent material can be non-transparent in other wavelength ranges in some embodiments. Accordingly in one embodiment, the conductive material (e.g. the conductive oxide) is transparent, or semi-transparent, or it exhibits low optical absorption at a certain wavelength range.
In one embodiment, the capacitor is arranged in layers as follows:
In one embodiment, the thickness of the metal ion-coordinated organic complex layer (EC film) ranges between 5 nm and 1000 nm. In one embodiment, the thickness of the metal ion-coordinated organic complex layer ranges between 100 nm and 800 nm. In one embodiment, the thickness of the metal ion-coordinated organic complex layer ranges between 50 nm and 500 nm, or between 100 nm and 600 nm, or between 50 nm and 10 μm, or between 5 nm and 100 μm, or between 5 nm and 1 mm. In one embodiment, the thickness of the EC film is 280 nm. In one embodiment, the thickness of the EC film is ranging between 150 nm and 700 nm.
In one embodiment, the number of double layers (each double layer=metal linker layer+metal-ion organic complex layer) is ranging between 2 and 50 layers. In one embodiment, the number of double layers is 18 layers (18 linker+18 complex). In one embodiment, the number of (linker/organic complex) layers is ranging between 2 and 40, between 5 and 30, between 10 and 20 layers. In one embodiment, the number of (linker/organic complex) layers is ranging between 4 and 100, between 5 and 1000, or between 10 and 50,000 layers or between 10 and 100,000. Any other number of layers is applicable to embodiments of this invention. As described herein, the layers can be formed by any method including spin-coat, dip-coat, spray-coat, CVD, PVD, and other methods as described herein. Some embodiments described herein below with regards to spin coating of the layers, are applicable to other coating methods (e.g. to spray coating and/or to dip coating) as known to the skilled artisan. These embodiments when relate to other coating techniques are included in this invention.
In one embodiment, the thickness of the PPC layer ranges between 15 μm and 20 μm. In one embodiment, the thickness of the PPC layer ranges between 10 μm and 30 μm. In one embodiment, the thickness of the PPC layer ranges between 10 μm and 20 μm or between 1 μm and 10 μm, or between 500 nm and 50 μm, or between 50 nm and 5 mm. Any other thickness of the PPC layer may be applicable to embodiments of this invention. In one embodiment, the thickness of the polymer layer on the second substrate ranges between 50 nm and 500 nm. In one embodiment, the thickness of the polymer layer ranges between 100 nm and 1000 nm or between 200 nm and 400 nm. In one embodiment, the thickness of the polymer layer on the second substrate is 300 nm. In one embodiment, the thickness of the carbon layer on the second substrate ranges between 10 μm and 20 μm. In one embodiment, the thickness of the carbon layer on the second substrate is 15 μm±5 μm. In one embodiment, the thickness of the carbon layer on the second substrate is 15 μm. In one embodiment, the thickness of the carbon layer on the second substrate is at least 5 μm or at least 1 μm or at least 15 μm or at least 20 μm. In one embodiment, the thickness of the carbon layer on the second substrate ranges between 1 μm and 200 μm.
In one embodiment, the thickness of the electrolyte layer is ranging between 100 μm and 200 μm or between 100 μm and 300 μm. In one embodiment, the thickness of the electrolyte layer is 180 μm. In one embodiment, the thickness of the electrolyte layer is 280 μm. In one embodiment, the thickness of the electrolyte layer is any thickness that fits operation of the device as known in the art. In one embodiment, the electrolyte layer comprises an absorbent material soaked in liquid electrolyte. In one embodiment, the absorbent (or adsorbent) material is a paper. In one embodiment the absorbent material is cloth. In one embodiment, the absorbent material is a porous material. In one embodiment, the absorbent material is a polymer. In one embodiment, the absorbent material is clay. In one embodiment, the electrolyte absorbent material comprises metal, metal oxide, metal alloy or a combination thereof. In one embodiment, the electrolyte is provided with no additional absorbent/adsorbent material. In one embodiment, the electrolyte is in a liquid form. In one embodiment, the electrolyte is a gel electrolyte. In one embodiment, the electrolyte is a solid electrolyte. In one embodiment, a spacer is provided. According to this aspect and in one embodiment, the spacer is a closed or partially-closed frame, into which the electrolyte is added. In one embodiment, the spacer encloses the electrolyte. In one embodiment, the spacer is a frame placed between the first electrode and the second electrode, and inside the space formed within the spacer between the electrodes, the electrolyte is being held. In one embodiment, the purpose of the spacer is to secure the electrolyte in place. In one embodiment, the purpose of the spacer is to prevent leakage of the electrolyte. One embodiment of a spacer is shown in
In one embodiment, the first substrate, the second substrate or a combination thereof is made of a material or comprises a material selected from the group consisting of silicon dioxide and organic polymers. In one embodiment, the first substrate, said second substrate or a combination thereof comprises a material selected from glass, quartz, polyethylene terephthalate (PET), PDMS, or any combination thereof. In one embodiment, the substrate is flat. In one embodiment, the substrate is curved. In one embodiment, the substrate has a cylindrical shape. In one embodiment, substrate geometry is selected from a circle, a sphere, a rectangle, a square, a cube, a cylinder, a spiral, a triangle, a box, a tear-drop shape. Any other shape or geometry is applicable to substrates of this invention as known in the art. In one embodiment the substrate is rigid. In one embodiment, the substrate is flexible. According to this aspect and in one embodiment, the substrate may be curved, bent, folded, rolled or twisted to fit a desired geometry. In one embodiment, the capacitor is a supercapacitor. In one embodiment, the substrate is attached to a conductive oxide as described herein. In some embodiments, the substrate is a conductive oxide. According to this aspect and in one embodiment, the substrate and the conductive oxide are one. In such cases, the substrate and the conductive oxide are referred to as the ‘substrate’ or as a ‘conductive substrate’. Any embodiments described herein with regards to a conductive oxide on a substrate are also applicable to a ‘substrate’ that is by itself a conductive material. In one embodiment, the capacitor is a hybrid capacitor, wherein the first electrode is a battery-type electrode and the second electrode is a capacitive electrode. In one embodiment, the first electrode functions as an electrochemical electrode (where a redox reaction occurs) and the second electrode functions as an electrostatic electrode (capable of holding charge such as electrons). In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is having a transmittance difference between the oxidized and the reduced states of 10% and higher. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is having a transmittance difference between the oxidized and the reduced states of 64% and higher. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is having a transmittance difference (ΔT) between the oxidized and the reduced states of 30% and higher, or of 20% and higher, or of 40% and higher, or of 50% and higher, or of 60% and higher, or of 70% and higher, or of 80% and higher. Parameters such as the metal ion in the organic complex, the ligand of the complex, and the choice of the electrolyte may affect the transmittance difference between oxidized and reduced states of the film. In one embodiment, transmittance contrast ratio of devices of this invention ranges between 24% and 27%. In one embodiment, the transmittance at one state (e.g. charged state) is about 40% while the transmittance at the other state (e.g. discharged) is about 12%. In one embodiment, transmittance contrast ratio of devices of this invention between charged and discharged states is ranging between 20% and 50%, or between 10% and 60%, or between 10% and 80%, or between 5% and 90%. In one embodiment, charge stability V1/2 of devices of this invention is at least 60 min. In one embodiment color stability V1/2 of devices of this invention is at least 38 min.
In one embodiment, the device operates under low potentials, for example, −0.6 V to 2 V. According to this aspect and in one embodiment, the device is charged by constant current, and the voltage that develops across the device is limited to a certain range. For example, the voltage is limited to the range of −0.6 V to 2 V. According to this aspect and in one embodiment, other potential ranges can be defined for the charge/discharge voltage limitation. For example, a voltage range of −1.0 V-2.5 V can be set as the voltage limit of the device during charge/discharge cycles. Devices of this invention display high energy density, and high power-density. For example, energy density of ˜2.2 Wh·kg−1 and power density of ˜2529 W·kg−1 have been measured for devices of this invention in one embodiment. In embodiments of this invention, the energy density of devices of this invention ranges between 1 Wh/Kg and 52 Wh·kg−1. In some embodiments, energy density of devices of this invention ranges between 1 Wh/Kg and 100 Wh·kg−1. In one embodiment, the device maintains at least 90% of its initial energy density after 3000 charge/discharge cycles. In one embodiment, the device maintains at least 75% of its initial energy density after 3000 charge/discharge cycles. Other energy density values can be obtained with devices of this invention, depending on the active materials used in embodiments of this invention. In some embodiments, the power density of devices of this invention ranges between 930 W·kg−1 and 6500 W·kg−1. In some embodiments, the power density of devices of this invention ranges between 100 W·kg−1 and 20,000 W·kg−1. Other power density values can be obtained with devices of this invention, depending on the active materials (e.g. the organic complex and capacitive materials) used in embodiments of this invention. Devices of this invention have high coulomb efficiency. For example and in one embodiment, the coulomb efficiency of devices of this invention is 99%. In one embodiment, the coulomb efficiency of devices of this invention is higher than 99%. In one embodiment, the coulomb efficiency of devices of this invention is higher than 90% or is higher than 95% or is higher than 99.5%. In one embodiment, coulomb efficiency of devices of this invention ranges between 90% and 99.99%. In one embodiment, coulomb efficiency of devices of this invention ranges between 75% and 99.99%. In some embodiments, devices of this invention provide a short charging time. For example and in one embodiment, charging time for a device of this invention is ˜2 s. In some embodiments, the charging time of devices of this invention ranges between 2 s and 60 s. In some embodiments, the charging time of devices of this invention ranges between 1 s and 5 min. Charging time depends on the amount of current applied. In some embodiments, charge retention (V1/2) in devices of this invention is ˜60 min. In some embodiments, charge retention of devices of this invention ranges between 25 min and 60 min. In some embodiments, charge retention of devices of this invention ranges between 20 min and 180 min. Other charge retention values can be obtained with devices of this invention, depending on the active materials and other parameters of devices used in embodiments of this invention. In some embodiments, the capacitance of the PPC layer is 10.7 F/g. In one embodiment, devices with different capacitive material, with different geometry or composition, exhibit other values of capacitance. In one embodiment, as described herein above, other capacitive layers can be used.
Devices of this invention provide stability, both in color and energy, for many charge-discharge cycles. For example, more than 1000 consecutive charging-discharging cycles have been demonstrated for a device of this invention in one embodiment. In one embodiment, devices of this invention exhibit color and energy stability for more than 500 cycles, for more than 1000 cycles, for more than 2000 cycles, for more than 3000, 5000 or 10,000 charging-discharging cycles. In one embodiment, devices of this invention exhibit/maintain color stability higher than 90% in terms of ΔT % compared to the initial ΔT % value, and energy stability higher than 90% compared to the initial energy value, for more than 500 cycles, for more than 1000 cycles, for more than 2000 cycles, for more than 3000, 5000 or 10,000 charging-discharging cycles. Devices of this invention exhibit controlled temperature during operation in some embodiments. In some embodiments, no significant changes in device temperature were indicated under the operating conditions. In one embodiment, there are no changes in device temperature during operation. In some embodiments, the temperature changes of devices of this invention under operation are small. In some embodiments, the temperature changes of devices of this invention is less than 1° C. during operation. In some embodiments, the temperature changes of devices of this invention is less than 2° C. during operation. In some embodiments, the temperature changes of devices of this invention is less than 3° C. or less than 5° C. or less than 10° C. or less than 15° C. or less than 20° C. during operation. In some embodiments, the temperature change described herein above (e.g. less than 1° C.) is effective when the device is operated for at least 1000 charge/discharge cycles, or for when the device is operated for at least 2000 charge/discharge cycles or for at least 5000 charge/discharge cycles or for a number of cycles ranging between 1 and 10,0000 cycles or for a number of cycles ranging between 1 and 5000 cycles, or between 1 and 2000 cycles, or between 1 and 1000 cycles. In some embodiments, device temperature change under operation is small. In some embodiments, the device temperature change does not interfere with device function.
In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 40% of its maximum contrast ratio after 50 switching cycles between oxidized and reduced states. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 54% of its maximum contrast ratio after 1000 switching cycles between oxidized and reduced states. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 90% of its maximum contrast ratio after 1000 switching cycles between oxidized and reduced states. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, is able to retain at least 70%, or at least 80%, or at least 95% of its maximum contrast ratio after 1000 switching cycles or after 1300 switching cycles, or after 1500 switching cycles, or after 2000 or 3000 or 5000 or 10,000 cycles between oxidized and reduced states. The choice of the metal-ion organic complex used, may affect the stability % described herein above in terms of contrast ratio following a certain number of cycles.
In one embodiment, the capacitor of this invention comprising:
In one embodiment, the electrochromic film comprising a metal ion-coordinated organic complex. In one embodiment, the capacitive material layer comprises a polymer or carbon or a combination thereof. In one embodiment, the capacitive material layer comprises a layer of polymer attached to a layer comprising carbon. In one embodiment, the first conductive oxide and said second conductive oxide, each independently comprises an electrical contact capable of connecting said conductive oxides independently to an external device. In one embodiment, the metal ion-coordinated organic complex comprises a metal-ion polypyridyl complex. In one embodiment, the electrochromic film comprising metal ion-coordinated organic complex, comprises from 2 to 80 layers of said metal ion-coordinated organic complex, said layers are linked to each other by a metal linker. In one embodiment, the metal ion in the metal linker is at least one metal ion selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y.
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex represented by Formula I:
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex, said polypyridyl complex is represented by Formula II:
Formula II is represented herein above with M=Fe. However, other transition metals can be metal ion M in formula II above. For example and in one embodiment, metal ion M is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, Cr, Rh, Ru, Os or Ir.
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex, said the pyridyl complex is represented by one of the following formulas, or by a mixture of the following formulas, or by a combination of the following formulas with molecules comprising different metal centers or ligands (according to the general formulas I and II):
In one embodiment, the polypyridyl complex is a mixture of polypyridyl complexes.
In one embodiment, this invention provides a device comprising:
In one embodiment, the device further comprising an optical detector. In one embodiment, the device further comprising a light source. In one embodiment, the device further comprising a processor for receiving input signal from said optical detector and to provide control signal to said device. In one embodiment, the control comprising at least one of initiate charging, halt charging, initiate discharging, halt discharging. An embodiment of such device is illustrated in
In one embodiment, the term ‘optionally’ in the phrase describing a power source that is optionally connected by a first/second electrical contacts to the first/second electrodes means, that the electrical contact can be connected or disconnected upon demand. Accordingly and in one embodiment, the connection between the power source and the electrodes includes a switch, a gate or any other electronic or optoelectronic component that can allow or interrupt, make or break, electronic contact between the power source and the electrodes upon demand. The electrical contact can also be made or be removed manually, by manually connecting/disconnecting a clamp, a wire, a plug to make/break the connection. The description above with regards to ‘optionally’ also refers to the optional connection of the load to the electrodes in the phrase describing a load that is optionally connected by a first/second electrical contacts to the first/second electrodes, as described herein. According to this aspect and in one embodiment, electrical contacts of this invention comprise or are attached to a switch or to a gate or to a plug, or to a clamp or to any other on/off element for electrically connecting/disconnecting two or more elements in devices of this invention as known in the art.
In one embodiment, the battery-type electrode is also referred to as battery-like electrode. In one embodiment, the battery type electrode comprises only one type of film of active material (one type of film comprising linker and metal-ion organic complex). According to this aspect and in one embodiment, the battery type electrode comprises only one type of metal ion in the metal-ion coordinated organic complex. In one embodiment, the film on the first electrode does not comprise two separate films such that one film comprises one type of metal ion in the metal-ion organic complex and the other film comprises another type of metal ion in the metal-ion organic complex. In one embodiment, devices of this invention do not require optical irradiation to induce charging. In one embodiment, devices of this invention do not require optical irradiation to induce discharging. In one embodiment, devices of this invention do not require electromagnetic irradiation to induce charging. In one embodiment, devices of this invention do not require electromagnetic irradiation to induce discharging. In one embodiment, devices of this invention do not require applied potential to induce discharging. According to this aspect and in one embodiment, devices of this invention can be discharged without applying an external potential/voltage on the device. According to this aspect and in one embodiment, discharge of devices of this invention occur spontaneously. In one embodiment, first electrodes of this invention do not comprise two layers wherein the first layer comprises one type of metal ion in the organic complex and the second layer comprises a second type of metal ion in the organic complex.
In one embodiment, devices of this invention comprise one type of metal ion in the metal-ion organic complex, the metal ion is selected from: Fe or Ru or Os or Cu or Ni or Co or Zn. Other metal ions can be used as the metal ion in the metal ion organic complex. For example and in one embodiment, any transition metal ion that is capable of undergoing oxidation/reduction in a device-suitable potential range can be included as the metal-ion in metal-ion organic complexes used on electrodes of this invention.
In one embodiment, devices of this invention as described herein above, are provided without a load or without a circuit comprising a load. According to this aspect and in one embodiment, devices of this invention are provided with a power supply and can be connected to any circuit/load upon demand. Therefore in one embodiment, this invention provides a device comprising:
In one embodiment, this invention provides a battery, the battery comprising:
wherein said electrochromic film comprising metal ion-coordinated organic complex.
According to this aspect and in one embodiment, both electrodes (first and second electrodes) are electrochemical or battery-type electrodes. In one embodiment, during operation, the reaction at both electrodes is an oxidation/reduction reaction. According to this aspect and in one embodiment, both electrodes comprise an electrochromic material. In one embodiment, the battery is a rechargeable battery. In one embodiment, the charging level of the battery can be determined by the color of one or of the two electrodes. In one embodiment, the second electrode comprises metal. In one embodiment, the second electrode comprises a conductive surface. In one embodiment, the second electrode comprises a conductive oxide. In one embodiment, the second electrode comprises a metal-ion organic complex. In one embodiment, the metal ion organic complex on the second electrode is different from the metal ion organic complex on the first electrode. In one embodiment, the metal ion in the metal ion organic complex on the second electrode is different from the metal ion in the organic complex present on the first electrode. In one embodiment, the metal ion organic complex on the first electrode, or on the second electrode, or on both first and second electrodes is a polypyridyl complex.
In one embodiment, this invention provides a battery, said battery comprising:
In one embodiment, this invention provides an electrode, the electrode comprising an electrochromic material. In one embodiment, said electrochromic material comprising metal ion-coordinated organic complex. In one embodiment, the electrode further comprising an electrical contact. In one embodiment, the electrode comprises a conductive surface attached to the electrochromic material. In one embodiment the electrical contact is attached to the conductive surface. In one embodiment, this invention provides an electrode comprising:
In one embodiment, this invention provides an electrode comprising:
In some embodiments, this invention provides an electrode comprising a polymer and carbon. In one embodiment, the electrode is a capacitive electrode. In one embodiment, the electrode further comprises an electrical contact. In one embodiment, the polymer is a conducting polymer. In one embodiment, the polymer comprises PEDOT, PSS or any combination thereof. In one embodiment, the carbon comprises, CNT's, graphene, carbon nanoparticles, or other porous carbon material. In one embodiment, the CNT is MWCNT. In one embodiment, the CNT is SWCNT. In one embodiment, the CNT is a mixture of MWCNT and SWCNT. In one embodiment, the polymer and the carbon are provided as different layers in electrodes of this invention. According to this aspect and in one embodiment, a layer of polymer is attached to a layer comprising carbon in electrodes of this invention. In one embodiment, the electrode comprises a layer, the layer comprising a mixture of polymer and carbon-comprising material. In one embodiment, the electrode comprises both separate layer(s) (comprising either polymer or carbon material but not both) and mixed layer(s) comprising both carbon and polymer. It should be noted that the term ‘carbon’ here refers in some embodiments to a material comprising carbon atoms only or comprising predominantly carbon atoms or comprising a portion where only carbon atoms exist. Such carbon material, except for surface bound groups is an inorganic material in the sense that it does not comprise e.g. H atoms in its backbone. Accordingly in some embodiments, the term ‘carbon’ does not refer to an organic material comprising carbon atoms in its skeleton/backbone. According to this aspect and in one embodiment, the carbon material is selected from the group consisting of: CNT's, graphene, fullerenes, carbon nanoparticles, aggregates of carbon nanoparticles, carbon sheets, carbon rods, porous carbon, graphite, or any combination thereof. In one embodiment the term carbon refers to a material wherein at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99% of its atoms are carbon atoms.
PEDOT:PSS is also used for creating better adhesion of the CNT to the FTO/ITO in some embodiments.
In another embodiment, the capacitor, the battery, the electrode, or other devices of this invention are not electrochromic or exhibit less pronounced electrochromic properties. According to this aspect and in one embodiment, the metal-ion organic complex in such devices does not show pronounced electrochromic behavior. In one embodiment, the color difference between the oxidized and reduced states of the device, is not pronounced, or is not detectable, or it does not remain stable for a large number of charge/discharge cycles. However, such devices are also included in this invention as capacitors, batteries and electrodes in view of their energy storage properties. Accordingly, any aspect described herein with regards to electrochromic devices (except for embodiments describing the electrochromic property) is applicable to devices that are not electrochromic, to devices that are only slightly electrochromic or to devices in which the electrochromic property is not utilized. Such embodiments and devices are included in this invention.
In one embodiment, the electrochromic electrode of this invention changes color from purple to transparent when charged and from transparent to purple when discharged. However, many other colors and color changes are included in embodiments for electrodes of this invention. In one embodiment, the color change depends of the redox ion and on the ligand in the metal-ion organic complex. Accordingly, changing the metal ion (e.g. to another metal ion not Fe), may result in different colors for the charged/discharged states. Changing the metal ion (e.g. to another metal ion not Fe), may result in different colors for the oxidized/reduced states. In addition, changing the ligand of the metal-ion organic complex may change the color of the complex and therefore of the electrode in the charged/discharged states. See for example colors of Ru and Os complexes and the color of a Fe complex with a different ligand shown in
Process of Producing Devices of this Invention
In one embodiment, this invention provides processes for producing electrodes, capacitors, batteries, and any other energy storage devices of this invention.
In one embodiment, this invention provides a process of producing a capacitor, said capacitor comprising:
wherein said electrochromic material comprising metal ion-coordinated organic complex;
said process comprising:
In one embodiment, the order of the process steps is changed. According to this aspect and in one embodiment, the second electrode can be prepared before the first electrode is prepared or vice versa. In one embodiment, the electrolyte is provided on the first electrode first, and the second electrode is then attached to the electrolyte on its other side. In another embodiment, the electrolyte is first attached/provided on the second electrode, and the first electrode is then attached to the electrolyte on its other side. In one embodiment, the first electrode, the second electrode or both are prepared in advance and kept until the capacitor is being assembled with the electrolyte. A batch of first/second electrodes can be prepared in advance and a capacitor can be constructed by adding the electrolyte layer as needed. In one embodiment, the first conductive oxide and the second conductive oxide, each independently comprises an electrical contact capable of connecting said conductive oxides independently to an external device. Electrical contacts are known in the art. For example, and in one embodiment, the electrical contact is a metal contact. In one embodiment, the metal contact is a metal wire/stripe attached on one side to the conductive oxide of an electrode, and on the other side directly or through an additional wire/clamp, or through an on/off switch, or through other circuit elements to a power source/load/other electronic circuit elements etc. In one embodiment, the step of applying a film comprising metal ion-coordinated organic complex onto said first conductive oxide surface, thereby forming a first electrode comprises:
In one embodiment, the metal ion-coordinated organic complex comprises at least one functional group, said functional group capable of binding to said metal linker. In one embodiment, the binding comprises a coordination bond between said functional group and said metal linker. In one embodiment, the metal ion-coordinated organic complex is a metal-ion polypyridyl complex. In one embodiment, the applying steps comprise one or more of roll-to-roll, spin coating, dip coating, spray coating, PVD, CVD. In one embodiment, the polypyridyl complex comprises one or more isomers of the same compound, or a mixture thereof. In one embodiment, the isomers are enantiomers and the polypyridyl complex comprises one or two enantiomers of the same compound or a mixture of said one or two enantiomers. In one embodiment, the applying steps comprise a spin coating step. In one embodiment, the spin coating step to apply the metal linker has a first spin rate and a first spin time and the step of applying the metal-ion coordinated organic complex has a first spin rate, and a first spin time. In one embodiment, the first spin rate is from 100 rpm to 2000 rpm, and the first spin time is from 0.3 sec to 60 sec. In one embodiment, the spin coating step to apply the metal linker has a second spin rate and a second spin time and the step of applying the metal-ion coordinated organic complex has a second spin rate and a second spin time. In one embodiment, the second spin rate is from 200 rpm to 3000 rpm, and the second spin time is from 1 second to 120 seconds.
In one embodiment, both applying steps are repeated to obtain from 2 to 80 layers. In one embodiment, the metal linker is applied as a metal ion complex.
In one embodiment, following the step of applying at least one metal-ion coordinated organic complex to form a layer and prior to the step of repeating the applying steps to obtain a multiple layer EC material, one or both of the following steps is performed:
In one embodiment, the solvent for said washing step is selected from the group consisting of alcohols, ethers, esters, halogenated solvents, hydrocarbons, ketones, or a mixture thereof. In one embodiment, the metal ion in the metal linker is at least one metal ion selected from the group consisting of Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y.
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex represented by Formula I as described herein below. In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex represented by Formula II as described herein above. Formula II is represented herein above with M=Fe. However, other transition metals can be the metal ion M in formula II above. For example and in one embodiment, metal ion M in formula II is a transition metal selected from Mn, Fe, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, Ru, Os or Ir.
In one embodiment, the metal ion-coordinated organic complex comprises a polypyridyl complex, the polypyridyl complex is represented by one of the following formulas, or by a mixture of the following formulas, or by a combination of the following formulas with molecules comprising different metal centers or ligands (according to general formulas I and II): 1DB M=Fe, 2DB M=Fe, 1SB M=Fe, 2SB M=Fe, 1TB M=Fe, 2TB M=Fe. The structural formulas of these compounds are shown herein above. In one embodiment, the Fe ion in 1DB, 2DB, 1SB, 2SB, 1TB, 2TB, shown herein above can be substituted with any other metal ion capable of undergoing oxidation/reduction reaction, for example, a transition metal ion selected from Mn, Co, Ni, Cu, Zn, Ti, Cr, Rh, Ru, Os or Ir.
In one embodiment, the metal linker is a mixture of metal linkers. In one embodiment, the polypyridyl complex is a mixture of polypyridyl complexes. In one embodiment, the step of applying at least one metal linker comprises applying the metal linker from a solution comprising the linker, and wherein the step of applying at least one metal-coordinated organic complex comprises applying the metal-coordinated organic complex from a solution comprising the metal-coordinated organic complex, and wherein said solutions comprise a solvent, said solvent is selected from the group consisting of THF, alcohols, ethers, esters, halogenated solvents, hydrocarbons, ketones, or a mixture thereof. In one embodiment, the concentration of the linker in the solution and the concentration of the metal-coordinated organic complex in the solution ranges between 0.1 mM and 10 mM.
Method of Using Devices of this Invention
In one embodiment, this invention provides methods of using electrodes, capacitors, batteries, and other energy storage devices of this invention.
In one embodiment, this invention provides a method of using the capacitor of the invention, the method comprising:
In one embodiment, any portion or step(s) of the method of using described above is by itself a method of using the capacitor of this invention and is included in methods of this invention.
In one embodiment, the color change is an indication of the charging/discharging level of said capacitor. In one embodiment, the capacitor is at a bleached state when charged and it is in a colored state when discharged. In one embodiment, the colored state is the more molecular-stable state, and the bleached state requires applied potential. In one embodiment, the color change is detected by an optical detector. In one embodiment, ‘connecting’ means closing a switch or switches in a previously assembled electronic circuit comprising the capacitor and the power source.
In one embodiment, devices of this invention (capacitors/batteries) are used as current indicators. In one embodiment, electrochromic devices of this invention (capacitors/batteries/electrodes) are used as optical gates.
In one embodiment, use of the invention comprise:
In one embodiment, the device further comprises an optical detector used to detect the color change. In one embodiment, the color change is detected by the eye. In one embodiment, the device further comprises a light source to illuminate the color-changing portion of the device (e.g. to illuminate the first electrode). In one embodiment, the device further comprising a processor for receiving input signal from said optical detector. In one embodiment, the processor provides a control signal to said device.
In one embodiment, the control signal is used to control at least one of: initiate charging, halt charging, initiate discharging, halt discharging. In one embodiment, the control signal is used to control at least one of opening a circuit, closing a circuit, opening a switch, closing a switch.
In one embodiment, devices of this invention, including electrodes, batteries, capacitors and supercapacitors can be used according to their function as elements/components in any electronic circuit that requires such elements/components. For example and in one embodiment, any electronic circuit that utilize a supercapacitor or a capacitor can comprise a supercapacitor/capacitor of this invention. Any device that requires electrode/battery/capacitor or supercapacitor, can utilize one or more of the electrode/battery/capacitor or supercapacitor of this invention as necessitate by the device.
Methods of Preparing an EC Film of this Invention
In one embodiment, this invention provides methods of depositing multiple layers of electrochromic materials onto a substrate thereby creating a multilayered EC assembly. The multilayered EC assembly is also referred to as an EC film or as an EC material or as EC component or as an EC layer in embodiments of this invention. These terms are interchangeable for certain embodiments of this invention.
The invention encompasses in one embodiment, multilayered EC materials composed of molecules of metal polypyridyl complexes. In one embodiment, one type of complex is used. In another embodiment, two or more different metal polypyridyl complexes are present in EC materials of this invention. The invention also encompasses multilayered EC materials composed of mixtures of at least two metal polypyridyl complexes.
Not to be limited by theory, it is believed that the metal linker complexes to a polypyridyl compound thereby forming a layer where the metal linker is able to complex to a second polypyridyl compound thereby creating a multilayered EC assembly. The combination of layer-by-layer principles with spin coating layering techniques achieves well-designed nanostructures. For example, it was shown that in one case, the different layers constructed of Fe-polypyridyl-complex and Pd metal linker form a 3D coordination network with particular advantageous properties.
One method of the invention produces EC material that is thermally and electrochemically robust in air with very high contrast ratios (ON/OFF ratios). The EC material may operate under low voltage and have practical switching times. Thus, an EC material that has very high ON/OFF ratios, homogenous coating, low-voltage operations, high electrochemical stability and durability (such as light and thermal durability), color versatility, and low switching times, is useful in a variety of applications as described herein. In addition to energy storage devices described herein above, the multilayered EC material has unique electrical properties suitable in applications such as smart windows, electrochromic windows, smart mirrors, optical filters, frequency doubling devices, spatial light modulators, pulse shapers, displays, signs, plastic electronics, lenses, sensors, to name a few. The method of the invention may be used for the formation of electrochromic coatings such as films.
As used herein, unless otherwise defined, the term “high electrochemical stability” refers to the capability of the EC material to retain high values of % ΔT, i.e., >90%, >95%, or >97%, after at least 1000, but preferably more than 3,000, 5,000, or 10,000 electrochemical switching cycles as immersed in an electrolyte solution/exposed to electrolyte gel/attached to a solid electrolyte, and exposed to air and to visible/UV light over a period of a few hours to a few days. In one embodiment, high electrochemical stability refers to the capability of the EC material to retain high values of % ΔT, i.e., >80%, >90%, >95%, or >97% or >99%, after at least 1000, but preferably more than 3,000, 5,000, 10.000 or 100,000 electrochemical switching cycles when immersed in an electrolyte solution or being in contact with electrolyte gel or with a solid electrolyte and exposed to air, to extreme atmosphere temperatures and to visible/UV light over a period of a few hours to a few years.
In one embodiment, the EC materials of this invention retained >90% of the original value of their contrast ratio after >1000 switching cycles.
The layer-by-layer (LBL) film-construction approach is an approach, based on the use of different kinds of inter-layers interactions such as electrostatic interactions and hydrogen bonding for the purpose of adhering layers of different materials to each other to form a film. See, Ariga et al., Phys. Chem. Chem. Phys. 2007, 9 (19), 2319, hereby incorporated by reference. The LBL approach relates to cases where films are formed by depositing alternating layers of materials that are known to have a certain type of interactions between them.
It was found by the inventors of this invention that coordination interactions can be used as the interactions between different layers that are deposited according to the LBL approach. Coordination interactions were never before used for LBL assembly of material layers. All previous methods were based on electrostatic interactions or hydrogen bonding as discussed herein above. In one embodiment, solely coordination interactions are used to attach the different layers in films of this invention.
EC materials can be applied onto substrates using a variety of deposition approaches and techniques. This invention encompasses a novel method of making EC materials by applying a linking metal and polypyridyl compound using layer by layer (LBL) deposition. The novel LBL process of the present invention can be used with any of the known deposition techniques. For example, LBL film formation using coordination-bonds is coupled with roll-to-roll, dip coating, spin coating, spray coating, PVD, CVD or a combination thereof in various embodiments of this invention.
In one embodiment, LBL processes of this invention are coupled with the spin coating technique. LBL is used to create a film of two or more components. Accordingly, in this embodiment, depositing EC material onto a substrate is performed using a combination of LBL and spin coating technique.
The inventors found that when LBL deposition of films comprising coordination interactions between the layers was combined with the spin coating technique, very uniform films of a relatively wide range of thicknesses were quickly and easily fabricated. The combination of LBL with spin coating is particularly applicable to well-designed nanostructures.
In one embodiment, the invention encompasses a method of making EC materials by applying to a substrate a metal linker and polypyridyl compound or complex using a layer by layer (LBL) deposition coupled with a spin coating technique. In particular, the method comprises making a multilayered EC material of different layers comprising at least one metal linker layer and at least one polypyridyl complex layer by LBL and spin coating to form a 3D coordination network. The method encompasses providing a substrate, applying by spin coating at least one metal linker, applying by spin coating at least one polypyridyl complex to form a layer, and optionally washing the layer with a solvent, optionally drying the layer, and repeating the applying steps to obtain an EC material of a desired thickness.
The application steps should be performed for a sufficient amount of time to ensure application of the metal linker solution or pyridyl compound/complex.
Typically, the method of making an EC material encompasses providing a substrate, applying at least one metal linker to the substrate by spin coating, applying at least one polypyridyl compound or complex to the metal linker by spin coating to yield a coated substrate, optionally washing the coated substrate, optionally drying the washed coated substrate, and repeating the applying sequence to obtain an EC material of a desired thickness.
Typically, the step of applying the metal linker by spin coating requires applying either a metal, metal salt, metal complex, or a combination thereof to the substrate, optionally, these materials are in solution. Subsequently, the substrate may be spun at a first suitable rate and for a first suitable time to obtain an even coating. In other embodiments, the substrate may be spun first, and only while spinning, the metal linker or other materials are applied to it.
If necessary, the substrate is spun at a second suitable rate and a second suitable time. Typically, the first spinning rate is between 100 to 2000 rpm, preferably the rate is between 400 rpm to 1600 rpm, and more preferably the first spinning rate is between 500 rpm to 800 rpm. Typically, the first spinning time is between 0.3 sec to 60 sec, preferably the first spinning time is between 5 sec to 40 sec, and more preferably the first spinning time is between 10 sec to 20 sec. Typically, the second spinning rate is between 200 to 3000 rpm, preferably the rate is between 400 rpm to 2000 rpm, and more preferably the second spinning rate is between 600 rpm to 1500 rpm. Typically, the second spinning time is between 1 second to 120 seconds, preferably the spinning time is between 15 seconds to 90 seconds, and more preferably the second spinning time is between 30 seconds to 60 seconds.
Without being bound to any theory, it is believed that programming the spin coating process in two steps allows differentiation between two subsequent processes that are occurring during the spinning: the first process is the spreading of the material and the attachment of it to the substrate or to a layer on the substrate. This step requires relatively longer time, and therefore performs at slower rates. The subsequent step involves disposal of unattached molecules. This step requires higher speeds, as one has to overcome physical adsorption in order to dispose unattached material.
Typically, the step of applying the polypyridyl compound or complex by spin coating requires applying either a polypyridyl compound or a polypyridyl metal complex to the substrate coated with the metal linker, optionally, these materials may be in solution. Suitable solvents for the solution include, but are not limited to, tetrahydrofuran, ethyl ether, dichloromethane, methanol, acetonitrile. Similar solvents may be used to dissolve/disperse the metal linkers; for example, PdCl2 linker is soluble in THF. However, depending on the metal linker and the metal complex, other solvents may be used as long as the metal-linker or metal complex are dissolved or dispersed in such solvent.
Subsequently, the substrate may be spun at a first suitable rate and for a first suitable time to obtain an even coating. If necessary, the substrate is spun at a second suitable rate and a second suitable time. In one embodiment, the first spinning rate is between 200 to 800 rpm, preferably the first rate is between 400 rpm to 600 rpm, and more preferably the first spinning rate is about 500 rpm. Typically, the first spinning time is between 1 sec to 30 sec, preferably the first spinning time is between 5 sec to 20 sec, and more preferably the first spinning time is about 10 sec. Typically, the second spinning rate is between 700 to 1300 rpm, preferably the second rate is between 900 rpm to 1100 rpm, and more preferably the second spinning rate is about 1000 rpm. Typically, the second spinning time is between 10 seconds to 60 seconds, preferably the second spinning time is between 15 seconds to 45 seconds, and more preferably the second spinning time is about 30 seconds.
In one embodiment, the substrate includes, but is not limited to, a material selected from glass, doped glass, ITO-coated glass, FTO-coated glass, silica, silicon, doped silicon, Si(100), Si(111), SiO2, SiH, silicon carbide mirror, quartz, a metal, metal oxide, a mixture of metal and metal oxide, group IV elements, polydimethylsiloxane (PDMS) and related organic/inorganic polymers, mica, organic polymer, plastic, zeolite, clay, wood, fabric, a membrane, optical fiber, ceramic, metalized ceramic, alumina, electrically-conductive material, semiconductor, steel, or stainless steel. The organic polymer includes, but is not limited to, polyacrylamide, polystyrene, and polyethylene terephthalate. The substrate may be in the form of beads, microparticles, nanoparticles, quantum dots, nanotubes, films, flat flexible surfaces, or flat rigid surfaces. The substrate may also be optically transparent to ultraviolet (UV), infrared (IR), near-IR (NIR), and/or other visible and non-visible spectral ranges or portions thereof. Preferably, the substrate is a rigid support comprising ITO or FTO coated glass or a flexible support of ITO coated PET. More preferably, the substrate is selected from the group consisting of ITO or FTO coated polyethylene terephthalate, ITO coated glass or quartz, and FTO coated glass or quartz. Optionally, the substrate may comprise a template or coupling layer.
Preferably, the substrate is transparent and has conducting properties. The substrate can be an n-type semiconductor with high carrier concentration, which leads to low electrical resistivity. High transmission in the visible and near-IR regions of the electromagnetic spectrum due to a wide band gap is also a desirable property of the substrate in some embodiments.
Metals used in the invention include those that can work as a metal linker between the substrate and the pyridyl compound or complex material or between two pyridyl compounds or complex materials. In the latter case, the pyridyl complex may be the same or different. Typical metals include, but are not limited to, transition metals, lanthanides, actinides, or main group elements. Transition metals include Zn, Os, Ru, Fe, Pt, Pd, Ni, Ir, Rh, Co, Cu, Re, Tc, Mn, V, Nb, Ta, Hf, Zr, Cr, Mo, W, Ti, Sc, Ag, Au, and Y. Lanthanides include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu. Actinides include Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, or Lr. Main group elements include Zn, Ga, Ge, Al, Cd, In, Sn, Sb, Hg, Tl, or Pb. Preferably, the metal is Pd. The metal may be applied as a coordinate metal in either neutral or in an oxidation state. For instance, Pd can be applied as Pd or a Pd(II)-based complex. An example of Pd(II)-based complex is PdCl2(PhCN)2. Further, in one embodiment, the metals or metal complexes are applied from solution. Suitable solutions include, but are not limited to, ethers such as tetrahydrofuran and ethyl ether. Suitable metals and metal complexes, as well as methods of making the complexes, can be found in PCT publication WO 2014/061018, hereby incorporated by reference. Metals in the metal-coordinated organic complexes of the invention can be any of the metals described herein above.
As used herein, unless otherwise defined, the term “pyridyl complex” refers to a metal having one or more e.g., two, three, or four pyridyl compounds coordinated therewith.
The bipyridyl complexes used in the invention are generally tris-bipyridyl complexes of the general formulas (I) and (II) as described herein above.
One family of pyridyl complex used in the invention is an iron-based tris-bipyridyl complex of the general Formula II as described herein above.
Formula II is represented herein above with M=Fe. However, other transition metals can be substituted for metal ion M in formula II above. For example and in one embodiment, metal ion M is a transition metal selected from Mn, Fe, Os, Ru, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, or Ir.
In formulas I and II described herein above, X is a counterion and may be any suitable anion having a negative charge, e.g., −1 or −2. Counterions include, but are not limited to, Br−, Cl−, F−, I−, PF6−, BF4−, BH4−, BPh4−, OH−, ClO4−, NO3−, SO32−, SO43−, CF3OO−, CN−, alkylCOO−, arylCOO−, alkylSO3−, arylSO3−, or a combination thereof. The value of “m” represents the ratio between the oxidation state of the metal and the valence of the anion. Values of “m” include, but are not limited to, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, or 6.
In certain specific compounds, the tris-bipyridyl complex is a complex of the general Formula I, wherein M is Fe; n and m each is 2 or 3; X is PF6−; R1 to R18 each is H, A1 to A6 each independently is a group of the Formula III, wherein Rx is H; and (i) R19 each is C═C, i.e., [tris[4,4′-bis(2-(4-pyridyl)ethyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyridyl)ethyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); (ii) R19 each is C═C, i.e., [tris[4,4′-bis(2-(4-pyridyl)ethenyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyridyl)ethenyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); or R19 each is C≡C [tris[4,4′-bis(2-(4-pyridyl)ethynyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyridyl)ethynyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate).
Other compounds include the tris-bipyridyl complex of general Formula I, wherein M is Fe; n and m each is 2 or 3; X is PF6−; R1 to R18 each is H, A1 to A6 each independently is a group of the Formula IV, wherein Ry is H; and (i) R19 each is C═C, i.e., [tris[4,4′-bis(2-(4-pyrimidinyl)ethyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyrimidinyl)ethyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); (ii) R19 each is C═C, i.e., [tris[4,4′-bis(2-(4-pyrimidinyl)ethenyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyrimidinyl)ethenyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); or R19 each is C≡C [tris[4,4′-bis(2-(4-pyrimidinyl)ethynyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4,4′-bis(2-(4-pyrimidinyl)ethynyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate).
In certain specific compounds, the iron based tris-bipyridyl complex is a complex of the general Formula II, wherein n and m each is 2 or 3; X is PF6−; R1 to R18 each is H, A1, A3, and A5 each independently is a group of the Formula III, wherein Rx is H; B1 to B3 each is methyl; and (i) R19 each is C—C, i.e., [tris[4′-methyl-4-(2-(4-pyridyl)ethyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(4-pyridyl)ethyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); (ii) R19 each is C═C, i.e., [tris[4′-methyl-4-(2-(4-pyridyl)ethenyl)-2,2′-bipyridine]iron(II)]bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(4-pyridyl)ethenyl)-2,2′-bipyridine]iron(III)]tris(hexafluorophosphate); or R19 each is C≡C [tris[4′-methyl-4-(2-(4-pyridyl)ethynyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(4-pyridyl)ethynyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate).
Other compounds include the iron based tris-bipyridyl complex of general Formula II, wherein n and m each is 2 or 3; X is PF6−; R1 to R18 each is H, A1, A3, and A5 each independently is a group of the Formula IV, wherein Ry is H; B1 to B3 each is methyl; and (i) R19 each is C—C, i.e., [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate); (ii) R19 each is C═C, i.e., [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethenyl)-2,2′-bipyridine]iron(II)]bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethenyl)-2,2′-bipyridine]iron(III)]tris(hexafluorophosphate); or R19 each is C≡C [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethynyl)-2,2′-bipyridine]iron(II)] bis(hexafluorophosphate), or [tris[4′-methyl-4-(2-(5-pyrimidinyl)ethynyl)-2,2′-bipyridine]iron(III)] tris(hexafluorophosphate).
Pyridyl compounds and complexes and methods of making them are found in PCT publication WO 2015/075714 and WO 2014/061018, hereby incorporated by reference. Pyridyl moieties preferred in the invention include but are not limited to those represented by the following formulas as detailed and represented herein above: 1DB M=Fe, 2DB M=Fe, 1SB M=Fe, 2SB M=Fe, 1TB M=Fe, 2TB M=Fe. These formulas are represented herein above with M=Fe. However, other transition metals can be substituted for metal ion M in formula II above. For example and in one embodiment, metal ion M is a transition metal selected from Mn, Fe, Os, Ru, Co, Ni, Cu, Zn, Ti, C, Cr, Rh, or Ir.
One method of the invention creates EC materials, such as thin films, based on compounds 1DB M=Fe or 2DB M=Fe made by a method comprising providing a substrate, applying in a stepwise manner palladium dichloride complex and the pyridyl complexes (Compound 1DB M=Fe or 2DB M=Fe or a mixture) using spin coating with LBL to form a layer, optionally washing and drying the layer, and repeating the applying steps until the EC material has the desired number of layers or thickness. The combination of spin coating and LBL is referred to as a single deposition cycle. The invention encompasses methods where the deposition cycle is repeated to obtain an EC material with 2 to 40 layers, preferably 5 to 30 layers, and more preferably 10 to 20 layers. In one particular case, such as a film, the method includes 18 deposition cycles, where after every deposition cycle, the modified substrates were washed using acetone, and dried under N2 stream. The fabrication process of the films occurs at ambient conditions.
In one particular embodiment, the method of the invention comprises providing a substrate, applying a metal-linker complex solution by spin coating to form a metal-linker layer, applying a pyridyl compound or complex by spin coating to form a pyridyl layer, optionally washing the pyridyl layer, optionally drying the washed pyridyl layer, and repeating the applying steps to obtain an EC material with 2 to 80 layers.
The metal-linker solution and pyridyl compound or complex are described above. Typically, the rinsing (washing) step is performed with at least one volatile organic solvent. Such volatile organic solvents include those capable of evaporating at room temperature in one embodiment. Typical volatile organic solvents include, but are not limited to, CH2Cl2, acetone, methanol, ethanol, THF, acetonitrile, among others.
Gasses suitable for use in the invention for the drying step, include, but are not limited to, nitrogen, argon, helium, neon, xenon, and radon. Preferably, the gas is nitrogen. Alternatively, the drying step can be air drying.
One embodiment of the invention encompasses a method for making an EC material comprising providing a substrate, applying at least one metal linker, applying at least one metal-coordinated organic complex to form a layer, washing the layer, drying the layer, and repeating the applying steps to obtain a multiple layer EC material.
In one embodiment, the metal-organic complex comprises at least one functional group, the functional group capable of binding to the metal linker. In one embodiment, the binding comprises a coordination bond between said functional group and said metal linker. In one embodiment, the metal complex is a polypyridyl complex. In one embodiment, ‘pyridyl’ is used in short for ‘polypyridyl’.
In one embodiment, the applying steps comprise deposition techniques such as roll-to-roll, spin coating, dip coating, spray coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) or combinations thereof. In one embodiment, the metal-coordinated organic complex comprises one or more isomers of the same compound. In one embodiment, the metal-coordinated organic complex comprises any mixture of isomers of the same compound. In one embodiment, the isomers are enantiomers. In one embodiment, the metal-coordinated organic complex comprises one or two enantiomers of the same compound. In one embodiment, the metal-coordinated organic complex comprises a mixture of said one or two enantiomers. In one embodiment, the enantiomer mixture is a racemic mixture. In one embodiment, the applying step(s) comprise spin coating.
In one embodiment, no template or coupling layer is used or is present between the substrate and the metal linker layer in EC materials of this invention. In one embodiment, the layer-application steps are performed manually. In one embodiment, the layer-application steps are performed in a partially automated manner or in a fully automated manner. Automation of the layer application technique results in fast fabrication of the EC materials in one embodiment.
Embodiments that are described herein for polypyridyl complexes are suitable for other metal-coordinated organic complexes as well. Embodiments that are described herein for Pd metal linkers are suitable for other metal linkers as well. Counter ions in metal-coordinated organic complexes of this invention can be any counter ion as known to the skilled artisan. In one embodiment, the growth of the layers in assemblies of this invention is such that the thickness of each layer is the same or is similar to the thickness of other layers in the assembly. In other embodiments, various layer thicknesses can be obtained for different layers in an EC material of this invention.
Catalysts of this Invention
In one embodiment, this invention provides a catalyst. In one embodiment, this invention provides a catalyst for water splitting. In one embodiment, onset of water splitting can be monitored by color change of at least a portion of the device. In one embodiment, the color-change is induced by a change of the redox state of an ion within the device. In one embodiment, the catalyst is used to convert water to H2 and O2. In one embodiment, the catalyst comprises a multilayer comprising catalyst ions. In one embodiment, the catalyst ions are metal ions. In one embodiment, the metal ions are Pd ions. In one embodiment, the multilayer that functions as a catalyst for the water splitting reaction comprises an electrochromic entity. In another embodiment, the multilayer that functions as a catalyst for the water splitting reaction does not comprise an electrochromic entity.
Data Storage/Memory Devices of this Invention
In one embodiment, this invention provides a data storage device. In one embodiment, the data storage device comprises at least one redox center. In one embodiment, each redox center provides at least two states depending on its oxidation states. In one embodiment, the charge for each state can be calculated. In one embodiment, each state is also characterized by a certain color. According to this aspect and in one embodiment, each state has a distinct color and requires a distinct amount of charge to be set. According to this aspect and in one embodiment, the data storage device can be set to a certain state electrochemically, and the state can be evaluated or can be read using charge calculation (electrochemically) or using optical detection. In one embodiment, when more than one redox center is included in the device such that the two or more centers differ in their oxidation states and/or in their color and/or in the metal ion used, the color of the device can be a combination of the colors of each redox center. Accordingly, in one embodiment, two different redox centers each having two oxidation states may result in a device comprising three different device states. Each state is characterized by a distinct color and can be achieved using a specific amount of charge. In some embodiments, the device is based on an organic multilayer comprising metal ions, wherein at least a portion of the metal ions in the multilayer are capable of assuming more than one oxidation state. Data storage devices described herein are referred to as memory devices in some embodiments. Embodiments described herein below with respect to metal-organic multilayers are applicable to embodiments of a data storage/memory device comprising such or similar multilayers as described herein above.
As defined herein, in metal-coordinated organic complexes, a metal ion is coordinately bonded to at least one organic molecule (a ligand). In some embodiments, the metal-coordinated organic complex is referred to in short as “metal-complex”. In some embodiments, the metal-coordinated organic complex is referred to as “metal ion coordinated organic complex”. Similar names are used in embodiments of this invention including metal-ion coordinated organic complex, metal-ion organic complex, organic complex, metal-organic complex.
In some embodiments, EC material is referred to as EC component, EC layer, EC film. These terms are interchangeable in embodiments of this invention.
The term supercapacitor defines or describes the properties of the capacitor. Supercapacitor generally has higher specific energy but lower specific power when compared to a capacitor.
Capacitors have less energy density as compared to batteries. However capacitors can be charged/discharged much faster than batteries. Supercapacitors are devices that can be described as bridging the gap between capacitors and batteries. The range of specific energy and specific power of supercapacitors lies in between that of batteries and that of capacitors (though obviously some overlap may exist). When compared to capacitors, supercapacitors can accumulate more energy. However, their charge/discharge rate is slower. When compared to a battery, supercapacitors may accumulate less energy, but can be charged/discharged faster. This description of supercapacitors is evident from the Ragone plot of power density vs. energy density (or of specific power vs. specific energy) as known in the art. The Ragone plot shows the amount of energy available per unit mass, vs. how quickly that energy can be delivered.
The term ‘hybrid supercapacitor’ refers to hybridization of two electrodes with different energy storage mechanism: one is a battery-type electrode and the other is a capacitive (capacitor-like) electrode. The battery type, or battery like, or battery style electrode is the electrochemical electrode. The capacitive electrode is an electrostatic electrode in embodiments of this invention.
In certain embodiments of this invention, the term ‘power source’ can be exchanged with power supply, current source, voltage source, voltage supply, current supply and other similar terms as known in the art.
Silicon dioxide and silicon oxide are interchangeable in embodiments of this invention.
‘conductive’ means electrically conductive in embodiments of this invention. The unit seconds is abbreviated ‘s’ but in some embodiments it is also referred to as ‘sec’.
In one embodiment, ‘active material’ refers to an electrode material, for example the PPC and/or the metal-ion coordinated organic complex. In one embodiment, the active material is a material that supplies/receives electrons upon charge or discharge.
In one embodiment, the metal-ion complex and layers comprising it function or are referred to as ‘hole-storage layer(s)’ or as hole storage materials. In one embodiment, the capacitive (second) electrode (e.g. the electrode comprising PPC) is referred to or functions as an electron-storage layer.
In one embodiment, the metal linker is referred to in short as the ‘linker’. Oxidation/reduction is sometimes abbreviated to ox/red. Load can be referred to as an electrical consumer. Some embodiments described herein for the conductive oxides are applicable to any conductive material (not limited to oxides) and are included in this invention.
In one embodiment, the electrochromic material comprises a metal-ion organic complex.
In some embodiments, the abbreviation ‘dec’ is for ‘decade’ and is used for example in plots to describe a decade, a 10.
In one embodiment, this invention provides batteries. In one embodiment this invention provides power supply, current generator or a combination thereof. Embodiments described herein for a battery are applicable to power supply/current generator of this invention in some embodiments and are included in power supplies/current generators of this invention, and in processes of preparation and use thereof in some embodiments.
In one embodiment ‘transmittance’ refers to optical transmittance as known in the art.
In one embodiment, the term “a” or “one” or “an” refers to at least one. In one embodiment the phrase “two or more” may be of any denomination, which will suit a particular purpose. In one embodiment, “about” or “approximately” may comprise a deviance from the indicated term of +1% or in some embodiments, −1%, or in some embodiments, ±2.5%, or in some embodiments, ±5%, or in some embodiments, ±7.5%, or in some embodiments, ±10%, or in some embodiments, ±15%, or in some embodiments, ±20%, or in some embodiments, ±25%.
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Among the wide variety of transparent conductors that is available and is in use in the electrochromic (EC) field and are included in embodiments of this invention, transparent conducting oxides (TCO) are the most common ones. However, alternatives to TCO can also be found. For example, thin metal sheets (e.g. silver or gold); graphene and carbon nanotubes.
The two most common TCO which are in use both for research and industrial purposes, are indium tin oxide (ITO) and fluorine doped tin oxide (FTO). Usually these TCO's are deposited on glass, but in the plastic electronics industry, ITO can also be deposited on flexible substrates, such as polyethylene terephthalate (PET). These TCO's are included in embodiments of this invention.
ITO substrates are widely used due to the fact that it combines unique transparent and conducting properties. It is an n-type semiconductor with high carrier concentration, which leads to low electrical resistivity. Moreover, ITO shows high transmission in the visible and near-IR regions of the electromagnetic spectrum due to its wide band gap (
FTO substrates are also used widely, mainly for energy-efficient windows in architectural applications. FTO is also an n-type semiconductor, with large band gap, which allows it to be transparent in the visible range (
In the examples below, the following substrates were in use: FTO and ITO coated glass substrates, ITO coated polyethylene terephthalate (PET) substrates. For each substrate, a suitable cleaning procedure was developed. The clean substrates were kept in a sealed and dark container, until further use. It is to be noted that other transparent conducting substrates may be used to support the EC materials of the invention. Other cleaning procedures may be used to prepare the substrates of the invention for use as known to the skilled artisan.
EC materials can be applied on any of the substrates that were described above in various deposition approaches and techniques. Among the different approaches, the following two are the most common: one step approach—mainly common in fabrication of polymers-based films; and layer by layer (LBL) approach—mainly common when the film is constructed of two or more components. There is a large variety of techniques that can be combined with each of the two described deposition approaches. As examples roll-to-roll, spin coating, dip coating and spray coating can be considered, as well as PVD and CVD techniques.
LBL deposition is a well-studied approach, utilizing various types of inter-layers interactions such as electrostatic interactions and hydrogen bonding. It was discovered by the inventors that when combined with spin coating technique, very uniform films of a relatively wide range of thicknesses can be fabricated quickly and easily.
In this example, this combination of LBL approach and spin coating as a fabrication technique is utilized in order to achieve well-designed nanostructures. The different layers are constructed of Fe-complex (compounds 1DB M=Fe or 2DB M=Fe, see
In this embodiment, as the procedure above describes, the first deposition step is of palladium dichloride linker. The interaction between the Pd linker to the substrate was studied, in order to define whether this is simply physical absorption, or there are coordination interactions between the Pd and the substrate. Previous works describe the affinity of Pd(II)-based complexes to oxide substrates, such as silica and alumina, by coordination of Pd to the hydroxyl groups which are on the surface. However, no literature is found on the absorption of Pd(II)-based complexes on ITO or FTO. In a previous study, a coupling and template layer were used in order to attach the Pd linker to the substrate. However, this linking layer has electrically isolating nature, and therefore it affected the electrochemical characteristics of the films.
Control experiments were designed, in order to evaluate if coupling and template layers between the substrate and the metal linker are needed in the case of spin coating fabrication process or can Pd be directly attached to the substrates using this technique. Further experiments were designed in order to evaluate if Pd is indeed needed for the pyridyl-complex layer growth process. In the first two control experiments, the substrates were modified with coupling and template layer (according to a known procedure), and the film was built with and without Pd as the linker. In two additional control experiments, the substrates were not modified, and again the film was built with and without Pd. The results of those experiments were that only in the experiments where Pd was used, an effective growth was evident. From this it was concluded that the film growth is not based on physical absorption but on Pd mediated coordination between the layers. Moreover, since there was no difference in the growth of the films on modified substrates with respect to non-modified ones, it was concluded that Pd can be attached directly to the substrates.
It is noted that other metal-coordinated organic compounds can be used as the metal-coordinated organic complex, and other metal linkers or other metal linker complexes can be used as the metal linker. The metal-coordinated organic complexes may comprise other polypyridyl compounds, other complexes comprising functional groups other than pyridines, compounds comprising both pyridine and non-pyridine functional groups, linkers comprising metals other than Pd, linkers comprising other ligands etc.
In order to strengthen the above, and also to test whether Pd is present after further deposition steps, XPS measurements were performed, where the ratio between Pd and Fe was tested. The measurements were performed on films with different number of deposition cycles deposited on FTO on glass substrates in order to show that the growth is homogenous. The results are presented in table 1:
In a fully coordinated network, the ratio between Pd and the metal center, Fe, is calculated to be 1.5 atoms of Pd per each Fe atom (each complex coordinates three Pd atoms each is shared between two complexes). However, the results above show an average Pd/Fe ratio of 2.8±0.3, meaning excess of Pd. This indicates a porous film structure with embedded Pd atoms in between the layers. Moreover, the homogeneity of the film can be seen from the results, as the ratio stays constant as the number of deposition cycles increases. Without being bound to any theory, it is believed that the embedded atoms are those which are not coordinated to the metal complex in the assembly. These atoms are in excess of the atoms needed to connect between the complexes/layers through coordination bonds. As noted above, the results indicate that the film is homogeneous, as the ratio remains constant as the number of deposition cycles increases.
The films were characterized by UV/vis spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and spectroelectrochemistry (SEC). The surface of the films was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy.
1.3.1 ITO/Glass
As was described above, ITO substrates have unique transparent and conducting properties. These are substrates with low electrical resistivity, and high transmission in the visible and near-IR regions of the electromagnetic spectrum.
Compound 1DB M=Fe was deposited on ITO substrate, according to the described film fabrication method. Compound 1DB M=Fe has a characteristic metal to ligand charge transfer (MLCT) band at λ=578 nm that is increasing linearly as the number of deposition cycles increases (
The electrochemical and spectroelectrochemical properties of the film were evaluated in solution using three-electrode cell configuration consisting of the modified ITO substrate as working electrode, Pt wire as counter electrode and Ag/Ag+ as reference electrode. CV measurements of the film reveal reversible redox processes of Fe+2/Fe+3 pair (
The oxidation and reduction processes that occur in the film are detectable using optical spectroscopy: when the film is oxidized, the intensity of the MLCT band is significantly reduced, resulting in bleaching, while when it is reduced, the film exhibits a purple color. SEC experiments were done by applying double potential steps as a function of time and recording the optical response at λ=578 nm as the percentage of transmittance (% T) over time. Double potential step chronoamperometry is a technique where the potential of the working electrode is stepped forward for a specified period of time, then stepped back for a specified period of time. Current is monitored and plotted as a function of time. The results reveal a very high transmittance difference between the oxidized and the reduced states (i.e. contrast ratio) of 54%. Moreover the film is able to retain 95% of its maximum contrast ratio even after 160 switching cycles.
1.3.2 FTO/Glass
Films with both Fe-complexed compounds 1DB and 2DB were fabricated on FTO/glass substrates, according to the described film fabrication method. Both films exhibit linear growth versus the number of deposition cycles. Compound 1DB M=Fe has a characteristic MLCT band at λ=578 nm, which results in a purple color, while Compound 2DB M=Fe has two distinct MLCT bands at λ=452 nm and =598 nm. The combination of these two bands gives rise to blackish color of a compound 2DB M=Fe-based film (
As the number of deposition cycles increase, the MLCT bands increase linearly, for both compounds (
The surface and structure of compound 1DB M=Fe based film were characterized using electron microscopy. The surface area of the film was sampled using optical microscopy and AFM. Both methods reveal grain-like, homogenous surface (
Films of different sizes were fabricated, using the same fabrication method (
Stability to light and high temperature is one of the features that an EC material should own. Two samples of films comprising compound 1DB M=Fe were tested: one was kept exposed to day light, and the other was kept at 100° C. Both experiments last for more than 120 days, and are still running. The results were obtained by UV/vis absorbance.
The electrochemical and spectroelectrochemical properties of a film comprising compound 1DB M=Fe were evaluated using three-electrode cell configuration consisting of the modified FTO substrate, Pt wire and Ag/Ag+ wire as working, counter, and reference electrodes, respectively. CV measurements of the film reveal reversible redox processes of Fe+2/Fe+3 pair (
The oxidation and reduction processes that occur in the film are detectable using optical spectroscopy: when the film is oxidized, the intensity of the MLCT band is significantly reduced, resulting in bleaching, while when it is reduced, it has a purple color (
SEC experiments were done by applying double potential steps as a function of time and recording the optical response at λ=578 nm as the percentage of transmittance (% T) over time (
The contrast ratio can be changed as a function of the switching time: as the switching time is shorter, the contrast ratio is lower. However, even for switching time in the sub-second regime, the contrast ratio is still relatively high, when compared to equivalent systems (
Switching efficiency is defined as the time it takes for 95% of the maximum contrast ratio to be obtained. It teaches about the time it takes for the system to react to an applied electrical potential. A film based on compound 1DB M=Fe exhibits switching time of 1.92 seconds for oxidation and 1.48 seconds for reduction (
The electron transfer processes can be elucidated by studies of transient responses, such as cyclic voltammetry at different scan rates (
Measuring the electrochemical and spectroelectrochemical properties at different deposition cycles gives information about the structure and the internal organization of the film (
The electrochemical and spectroelectrochemical properties of a film comprising compound 2DB M=Fe were evaluated using three-electrode cell configuration consisting of the modified FTO substrate; Pt wire and Ag/Ag+ wire as working, counter, and reference electrodes, respectively. CV measurements of the film reveal reversible redox processes of Fe+2/Fe+3 pair (
The oxidation and reduction processes that occur in the film are detectable using optical spectroscopy: when the film is oxidized, the intensity of the MLCT band is significantly reduced, resulting in bleaching, while when it is reduced, it has a black color (
SEC experiments were done by applying double potential steps as a function of time, and recording the optical response at λ=598 nm as the percentage of transmittance (% T) over time. The results reveal contrast ratio of 33%. Moreover the film is able to retain 95% of its maximum contrast ratio even after 1000 redox cycles (
The previous sub-chapter described films based on separate systems of either compound 1DB M=Fe or compound 2DB M=Fe. This chapter presents films based on mixed systems of the two compounds. The motivation behind mixing the two compounds arises from the fact that a system based on compound 1DB M=Fe is more opaque (based on its contrast ratio, see
Mixing of two components into one system can be obtained in various ways: alternating depositions of each compound, either by alternate deposition of one layer of each compound or deposition in block configuration: a block of one compound followed by a block of the other compound. In the latter manner, the sizes of blocks can be equal or can vary in favor of one compound over the other. The size of each block can be controlled by the number of deposition cycles for each block.
Another way of deposition is by using a mixed solution of the two compounds in equal or different concentrations. The latter two systems (block and mixed-solution) were fabricated using the herein disclosed fabrication method.
The fabrication process using mixed solutions included alternating depositions of solutions of PdCl2(PhCN)2 and a solution of Fe polypyridyl complexes mixture (compounds 1DB M=Fe and 2DB M=Fe in equal amount). The block deposition utilized separated solutions of each complex. Both methods relied on the use of spin coating-LBL approach. In this example 18 deposition cycles were fabricated and according to UV/vis absorption, the growth trend was found to be linear, similar to the separated systems wherein only one complex has been used (
Electrochemical and SEC analysis show higher contrast ratio for the block systems, however when considering the obtained color, the mixed system seems the darkest (
The need for flexible EC films arose in the past few years due to their potential applications in the electronic industry, e.g. flexible displays. This kind of films is also interesting as it may allow installation of EC films on existing structures, which will reduce production costs compared to newly formed structures.
In this example, ITO/PET substrates (10 ohm/cm2) were purchased commercially. As was described above, ITO has unique transparent and conducting properties, which results in low electrical resistivity, and high transmission. When deposited on PET, a flexible transparent electrode is obtained. ITO/PET substrates were cleaned prior to further deposition steps. The cleaning procedure involved rinsing with ethanol, followed by immersion in acetone. The substrates were dried under air stream. Compound 1DB M=Fe was deposited according to the described film fabrication method. As disclosed herein. Compound 1DB M=Fe has a characteristic metal to ligand charge transfer (MLCT) band at λ=578 nm that is increasing linearly as the number of deposition cycles increases. (
The electrochemical and spectroelectrochemical properties of the film were evaluated using three-electrode cell configuration consisting of the modified ITO/PET substrate, Pt wire and Ag/Ag+ wire as working, counter, and reference electrodes, respectively. The film was held both in not-bent and in bent configurations. CV measurements of the non-bent film reveal reversible redox processes of the Fe+2/Fe+3 pair (
In some embodiments, for real time applications, EC films should be incorporated in a solid configuration. The basic structure of an electro-chromic device (ECD) consists of two-EC layers separated by an electrolyte layer. ECDs can be divided into two main categories: All-solid state ECDs, where the electrolyte is a solid organic or inorganic layer (not liquid or gel); and laminated ECDs, where the electrolyte is a liquid gel. Laminated ECD's are also considered as ‘solid state systems’ in some embodiments. Many parameters can affect the performances of the device: conductivity of the electrodes, spacer type and dimensions, electrolyte type and composition and device packing and sealing. As a result of the many affecting parameters, long process of optimization is required in order to fabricate good performing device. Another main challenge is the lifetime of the device, as devices tend to degrade with increasing number of redox cycles.
In this example, ECDs were constructed by sandwiching [Compounds 1DB and 2DB 118 FTO/glass], and a bare FTO, with an electrolyte gel in between the two electrodes. The contacts were made of silver-paste or copper tape, and the spacing between the two electrodes was achieved by introducing 50 μm double-sided tape. The electrochemical behavior of the ECDs was analyzed using cyclic voltammetry and chronoamperometry.
The electrochemical and spectroelectrochemical properties of a device based on a film comprising Compound 1DB M=Fe were evaluated by applying double potential steps between (−2.5 V) and (3V). The required potential window for such device operation is larger than the potential window required for a film in an electrolyte solution, due to the fact that in solid configuration, the viscosity of the (gel) electrolyte is higher, which results in higher resistance. SEC experiments were carried out by applying potential as a function of time, and recording the optical response at λ=571 nm (MLCT band peak) as the percentage of transmittance (% T) over time. The results reveal high contrast ratio of 50%. Moreover the film is able to retain 95% of its maximum contrast ratio even after 100 redox cycles.
The kinetics of the redox process were tested in the following way: a suitable potential was applied (e.g. 3 V), which results in bleaching of the device. This was followed by shutting off the potential and opening the circuit. The device then started to return to its stable state, e.g. the colored, reduced state. From the exponential decay of the transmittance percentage (% T) with time, the rate of color change was calculated and found to be 0.032 sec−1 (
Devices of different sizes were fabricated, using the same fabrication method. Larger switching times were required for full switching of larger devices. For example,
Solvents (AR grade) were purchased from Bio-Lab (Jerusalem), Frutarom (Haifa), or Mallinckrodt Baker (Phillipsburg, N.J.). Fluorine-doped-tin-oxide (FTO) coated glass substrates (6 cm×6 cm) and indium-tin oxide (ITO) coated polyethylene terephthalate (PET) substrates were purchased from Xinyan Technology LTD (Hong-Kong, China). ITO coated glass substrate (6 cm×6 cm) were purchased from Delta Technologies (Loveland, Colo.). ITO and FTO substrates were cleaned by sonication in ethanol for 10 min, dried under N2 stream and subsequently cleaned for 20 min with UV and ozone in a UVOCS cleaning system (Montgomery, Pa.). The slides were then rinsed with tetrahydrofuran (THF) and dried under N2 stream, and 130° C. for 2 h. ITO coated PET substrates were cleaned by immersion in ethanol and acetone, followed by drying under N2 stream. UV/vis spectra were recorded on a Cary 100 spectrophotometer (200-800 nm). The modified substrates were fixed in a Teflon holder and suitable clean substrates were used to compensate for the background absorption. All measurements were carried out at room temperature. Electrochemical measurements (cyclic voltammetry (CV), chronoamperometry (CA) and spectroelectrochemistry (SEC)) were carried out using a potentiostat (CHI660A or CHI660E). The layer by layer deposition steps were performed using a Laurell spin-coater, model WS-400A-6NPP/LITE.
A drop of 3.0 mM solution of PdCl2(PhCN)2 in THF was casted on FTO substrate, which was loaded on a spin coater stage. The substrate was spun at a speed of 500 rounds per minute (rpm) for 10 seconds, followed by spinning at a speed of 1000 rpm for 30 seconds. Subsequently, a drop of 0.6 mM solution of the EC compound (compounds 1DB M=Fe or 2DB M=Fe) in DCM/Methanol (1:1, v/v) was casted on the substrate, and was spun according to the same program. The substrate was immersed in acetone, for 1 min. and was dried under N2 stream. An UV/vis absorbance spectrum was recorded after each deposition cycle.
(a) Preparation of the electrolyte gel: Polymethylmethacrylate (PMMA, 700 mg), trifluoromethylsulfonamide lithium salt (300 mg), dry acetonitrile (7.0 g, ˜8.9 mL) and dry propylene carbonate (2.0 g, 1.7 mL), in 70:20:7:3 wt %, were added to a glass vessel in N2-filled glovebox and stirred vigorously for 24 h, giving a homogeneous casting electrolyte solution. (b) Device fabrication: A frame of 50-100 μm double sided tape was cut and taped on the film slide, leaving an edge for silver paste or copper tape contacts. The edge of a bare FTO substrate was also covered with silver paste or copper tape. The bare substrate was placed on top of the film slide, in such a way that the two conducting faces of the substrates were facing each other. The sides of the device were sealed using epoxy glue or UV-curable glue. Finally, the electrolyte gel was injected using a syringe between the two substrates.
The electrochemical behavior of the film was tested in a solution of 0.1M tetrabutylammonium hexafluorophosphate (TBAPF6) in ACN, by CV, CA and SEC. The measurements were performed in a three-electrode cell configuration consisting of (a) modified substrate (working electrode), (b) an Ag/Ag+(reference electrode), and (c) a Pt wire (counter electrode).
The electrochemical behavior of the electrochromic device (ECD) was measured by CA and SEC, which were carried out by applying potential window between −2.5 V and 3 V, with a time gap of 4 seconds.
As discussed above, mixing of two components into one system can be obtained in various ways: alternating depositions of each compound, deposition in block configuration: a block of one compound followed by a block of the other compound. In block deposition, the sizes of blocks can be equal or can vary in favor of one compound over the other. Another deposition scheme comprises deposition of a mixed solution of the two compounds in equal or different concentrations. Such mixed-layer system was fabricated using the described fabrication method comprising LBL and spin-coating. The fabrication process includes alternating depositions of 3 mM solution of PdCl2(PhCN)2 in THF, and equimolar solution of the Fe-polypyridyl complexes 1DB M=Fe and 2DB M=Fe (0.3 mM each) in 1:1 DCM Methanol, using our spin coating LBL approach. These two subsequent steps (Pd linker and Fe-complexes) are referred to as a single deposition cycle. The films consisted of 18 deposition cycles, where after every deposition cycle, the modified substrates were washed using acetone, and were dried under N2 stream. The fabrication process of the films was conducted at ambient conditions.
Compound 1DB M=Fe has a characteristic MLCT band at λ=578 nm, while compound 2DB M=Fe has two distinct MLCT bands at λ=452 nm and =598 nm. The combination of these two compounds gives rise to a MLCT band at λ=589 nm, that is increasing linearly as the number of deposition cycles increases (
Electrochemistry in Solution
The electrochemical properties of these systems deposited on ITO/PET 60 ohm/sq were evaluated using three-electrode cell configuration consisting of the modified ITO/PET substrate as working electrode, Pt wire and Ag/Ag+ wire as counter, and reference electrodes respectively. Chronoamperometry and cyclic voltammetry were measured in order to test the film's durability to bending: The film was measured when it was upright, then it was measured while bent in a curvature radius of 2.5 cm, and finally again when it was back upright. The electrochemical switching was performed by applying (−0.5 V) for 4 seconds and (2 V) for 8 seconds for few cycles, while the CV was recorded at a scan rate of 0.05 V/sec, at a potential window of 0-2 V. The results show no significant difference when the film was measured before or after the bending, as
The photographs in
ECDs were constructed by sandwiching such mixed-layer Fe-complexed films (1DB and 2DB|18|ITO/PET 60 ohm/sq) with a bare 60 ohm/sq ITO/PET. An electrolyte gel (Li salt in propylene carbonate, with or without PMMA as a plasticizer) or an ionic liquid was placed in between the two electrodes. The contacts were made of copper tape or silver paste, and the spacing between the two electrodes was achieved by introducing 50-200 μm double-sided tape. Chronoamperometry was measured in order to test the device's durability to bending: the device was measured when it was upright, then it was measured while bent in a curvature radius of 2.5 cm, and finally again when it was back upright. The electrochemical switching was performed by applying −2.5 V for 10 seconds and 3 V for 30 seconds for few cycles. The results show no significant difference when the device was measured before or after the bending, as
The photographs shown in
The Photographs shown in
The crystal structure of complexes 1DB M=Fe and 2DB M=Fe were obtained, and the library of complexes has been expanded to include complexes 1DB M=Ru and 1DB M=Os. The crystal structure of complexes 1DB M=Fe and 2DB M=Fe is presented in
Selective switching of an electrochromic surface was demonstrated, by depositing the EC material on a glass substrate that was only partially coated by ITO according to a certain pattern. Using this technique, the selective switching was used for “writing” and “erasing” with response to an external potential (see
Open circuit stability is defined as the ability of a material to restore its original state after being subjected to an external stimulus. It was found that after being oxidized, and therefore bleached, the assemblies (the films, i.e. the EC materials on a substrate in embodiments as described herein above) were able to get reduced, and therefore colorful, spontaneously. The spectroelectrochemical profile of an open circuit experiment is presented in
Few devices were connected in parallel. Such configuration allowed applying the same voltage to all the devices, while summing up the currents through each device. Also, connecting few devices together allowed increase of the active area, and by that overcoming resistivity issues which arises when it comes to larger surfaces (see
When combining two complexes with different redox potentials, the hierarchy of the assembly becomes an important parameter which determines the electrochemical properties of the assembly. In this example, dual-component systems were investigated: assembly of (1DB M=Fe and 1DB M=Ru) and assembly of (2DB M=Fe and 1DB M=Os). Table 2 presents the redox potentials of the different complexes, which allows the existence of three different outcomes depends on the hierarchy of the assemblies:
1) When the two components were mixed and deposited on the substrate randomly, both complexes should be electrochemically accessible and therefore active. This situation allows “three state system”, as the system can exhibit one of three states: (a) the two components are reduced; (b) one is reduced, and one is oxidized; (c) the two components are oxidized.
2) When the lower redox potential component is closer to the substrate than the higher redox potential component, oxidation of the top component was not possible, and therefore the system cannot reach a fully oxidized (fully bleached) state.
3) When the higher redox potential component is closer to the substrate than the lower redox potential component, reduction of the top component is not possible, which leads to charge trapping, as the top part is in its oxidized form, but won't be able to get reduced. This property of charge trapping can be used as new battery-like technology, as the trapped charge can be released on demand, by applying an external stimuli, e.g. light or over-potential. Every external stimulus has its own mechanism of operation. In general by applying a stimulus, one can overcome the energetic barrier that causes the charge trapping, and therefore the charge can be released.
The three different hierarchies (1, 2, 3 above) were studied for both presented systems: assembly comprising 1DB M=Fe and 1DB M=Ru and assembly comprising 2DB M=Fe and 1DB M=Os. In the case of assembly 1DB M=Fe and 1DB M=Ru, the lower redox potential component is complex 1DB M=Fe (Fe-based complex with redox potential of 1 V), and the higher redox potential component is complex 1DB M=Ru (Ru-based complex with redox potential of 1.2 V).
In the case of assembly 2DB M=Fe and 1DB M=Os, the lower redox potential component is complex 1DB M=Os (Os-based complex with redox potential of 0.8 V), and the higher redox potential component is complex 2DB M=Fe (Fe-based complex with redox potential of 1 V).
In this example, the formation of an integrated optical-electronic device was demonstrated, where the amount of available charge is indicated by color. The device has the design and operating characteristics of a hybrid supercapacitor: (i) the battery-like electrode consists of a coordination-based network of metal organic complexes bound to fluorine-doped tin oxide (FTO) coated glass. This redox-active assembly has a dual function as a hole storage layer and as a charge indicator, and (ii) the capacitive-like electrode is a combination of multi-walled carbon-nanotubes (MWCNTs) deposited on a layer of PEDOT:PSS, which is directly attached to FTO. Combining the thin layers of these functional materials results in a new device capable of powering a conventional diode in an electronic circuit.
In this example, iron polypyridyl complexes were used as molecular components for forming the electrochromic-hole storage layer as the battery-like electrode=[Fe|FTO/glass] (
The capacitive-like electrode is placed on top of [FTO/glass] (
The laminated electrochromic-hybrid supercapacitor (EHSC) consists of (i) [PPC|FTO/glass], as the reference and counter electrodes, (ii) an insulating spacer enclosing an electrolyte (see below for details), and (iii) [Fe|FTO/glass], as the working electrode (
The electrochemical properties of the device, [glass/FTO|Fe∥PPC|FTO/glass], were evaluated using cyclic voltammetry (CV) in a two-electrode cell configuration at a potential window of −0.4 V to 1.8 V. The CV clearly shows both capacity and Faraday currents, which is characteristic of a hybrid supercapacitor (
To demonstrate the synergic effect of the use of two distinct capacitor and battery-type electrodes (as shown above for the EHSC), two control devices have been fabricated having only one of these electrodes: (A) [glass/FTO∥PPC|FTO/glass] and (B) [glass/FTO∥Fe|FTO/glass]. For (A): when both MWCNT and PEDOT:PSS (=PPC) are used, only low double layer capacitance is observed (
The relationship between the charging-discharging of the EHSC and the current density is obtained from the galvanostatic charging-discharging (GCD) profiles. The GCD profiles were recorded at a potential range of −0.6 V to 2.0 V in current density ranges from 0.2 A·g−1 to 1.8 A·g−(
During device fabrication, a part of the MWCNT-layer at the center of the electrode (12 mm×17 mm) was mechanically removed to generate an optical window (3 mm×7 mm). This window (=charge indicator) enabled monitoring of the charge-storage and release by UV-vis spectroscopy. Since the MWCNT layer appears black while the PEDOT:PSS layer is bright, removing a portion of the MWCNT layer enabled optical transmittance through this area of the device. Spectroelectrochemical measurements showed the correlation between the applied potentials, the amount of charge stored, optical densities, and color (
The device was examined both for energy and color stability by GCD measurements. The initial energy density and color was maintained (˜90%) for 1000 consecutive charging-discharging cycles at a current density of 0.88 A·g−1 (
Moreover, an electric circuit was demonstrated with the EHSC as the energy storage device and power source, accompanied by the change in color in real time (
To conclude, this example demonstrated an integrated electrochromic-hybrid supercapacitor (EHSC) and showed two device configurations: the functional materials can be stacked in either a layered or in an in-plane architecture. In this example, the device with the hole in the middle is referred to. At the area of the hole there are no CNT's, so the architecture is in-plane and in other areas, where CNT's are present it is layered.
The structure having an optical window allows an optical read-out of the device's status in the optical transmission mode. Both configurations have similar characteristics. The metallo-organic layer has a dual role: as both the electrochromic material and as the hole storage layer. The storage of holes in this redox-active material is directly correlated with its color, allowing it to be linked to the charging state of the hybrid supercapacitor. The layered structure of the hybrid supercapacitor is a unique example of the useful synergistic effects that can be achieved by combining a set of completely different materials: in this case: a metal oxide, an organic polymer, MWCNTs, and a coordination-based metallo-organic polymer (the metal-ion organic complex). Polymers that have excellent electrochromic properties. The electrochromic-hybrid supercapacitor can be used in one embodiment to operate in a conventional circuit by powering a diode (=gate) that allows current to light up a LED. In an embodiment, if the circuit has a diode that has a threshold of 1V, a higher potential “opens” the diode and as a result the LED will light. Other electronic elements can be powered by the capacitor described herein. The capacitor described herein can be used as an element in a vast number of electronic circuits where capacitors or supercapacitors are required. The electrochromism property can be used to monitor the function and the operation state of any electronic circuit comprising capacitors of this invention.
This first-generation device exemplified herein has promising properties, since it exhibits high energy density and high power-density, high coulomb efficiency, and short charging times. Moreover it displays promising charging-discharging stability, coupled with electrochromism for 1000 consecutive cycles.
Materials Ethyl-propyl perylene diimide (EP-PDI), iron polypyridyl complex (
UV/Vis Spectroscopy. UV/Vis spectra were recorded on a Cary 100 spectrophotometer. The absorbance was measured using the Cary WinUV-Scan application program, version 4.20 (468) by Varian (200-800 nm), whereas the transmittance was measured using the Cary WinUV-Kinetics application program, version 4.20 (468) by Varian. FTO-coated glass substrates were used to compensate for the background absorption.
Electrochemical Characterization. Cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP) were carried out using CHI760E and CHI660E workstations. The following configurations of the electrochemical cells were used: [Fe|FTO/glass] or [PPC|FTO/glass](2 cm×2 cm) were used as the working electrode, Ag/Ag+ was used as the reference electrode, and a Pt wire was used as the counter electrode. Lithium perchlorate (LiClO4 0.1 M in propylene carbonate:acetonitrile=1:1, v/v) was used as the supporting electrolyte.
Formation of the Capacitive Electrode. [PPC|FTO/glass] was formed by weighing bare [FTO/glass] substrates (2 cm×2 cm) and spin-coating PEDOT:PSS/isopropyl alcohol (0.5 mL of PEDOT:PSS and 0.7 mL of isopropyl alcohol) at 500 rpm for 10 s and then at 1000 rpm for 30 s. Subsequently, the [PEDOT:PSS|FTO/glass] substrates were dried at 120° C. for 1 min. For the dispersion of MWCNTs, 1.0 mL of CHCl3 with 1.0 mg of MWCNT and 1.0 mg of EP-PDI were sonicated at 0° C. for 30 min (sonication at low temperature is used to prevent the formation of free radicals). The resulting suspension was drop-casted (0.3 mL-0.8 mL) onto [PEDOT:PSS|FTO/glass]. The electrode was kept at 120° C. for 15 min and washed with CHCl3 to remove the EP-PDI, until the CHCl3 solution was colorless. The resulting [PPC|FTO/glass] was dried at 120° C. for 30 min. The optical window (3 mm×7 mm, see
Fabrication of the Electrochromic Hybrid Supercapacitor (EHSC). A frame of double-sided tape (3M 9088; 210-μm-thick) was placed on [Fe|FTO/glass], leaving an exposed edge (1-2 mm) for copper tape contacts. Subsequently, Whatman filter paper (Cat No 1001-070, pore size 11 μm, thickness 180 μm) used as a dielectric layer was placed in this frame. The electrolyte solution was drop-casted on the filter paper. The [PPC|FTO/glass] electrode (2 cm×2 cm) was immersed in an electrolyte solution, (PC:ACN, 1:1 v/v, 0.1 M LiClO4), for 1 h. Then, [PPC|FTO/glass] was placed in parallel on top of the frame with the filter paper. The conducting surfaces of the two electrodes face each other. The [Fe|FTO/glass] is the working electrode, and [PPC|FTO/glass] serves as the counter/reference electrode. In this example, the same electrolyte solution was used for the paper and for soaking the PPC electrode. Other electrolytes can be used as known in the art.
In this example, charge storage and release in a multilayered nano-scale assembly is described. Stepwise assembly of nanoscale layers of molecules is an attractive and versatile approach for designing functional thin films. This approach enables fabrication of materials that can hold and release charge in response to electrochemical stimulation. Charge storage and release is coupled with color changes. The color change is an indication of the charging state of the device in some embodiments. The fabrication of a multilevel per bit organic memory cell (OMC) composed of ruthenium, iron and osmium polypyridyl complexes was demonstrated in this example. The OMC exhibits dual-function memory performance in which the information can be read optically as well as electrochemically.
The field of organic electronics suggests an alternative approach for micro- and nano-electronics compositions. Replacing the conventional metallic components by polymers (copolymer or homopolymers), blend of small molecules and metal organic compounds, offers the design of novel electronic systems with unique properties. Combining high electrical or ionic conductivity with distinct physical properties such as mechanical flexibility, opened the door for countless innovative inventions from energy-harvesting and wearable items to biomedical applications. Polymers and small molecules help to achieve light-weight, low cost and sustainable electronic components and can be used as a building blocks for tailor-made fabrication processes. Such approaches enable control over the composition of the system at the molecular level. In addition, such methods are compatible with new deposition techniques such as ink-jet printing, spin- and spray-coating which are useful for the design of complex electronic components made to deal with the challenges presented by advanced technologies. Due to the rapid development and involvements of information technology devices in our daily life (devices such as mobile phones, digital cameras and personal computers) the requirement for advanced data storage elements becomes essential. The traditional Si, Ge and other semiconductor industry faces the challenge of combining miniaturized devices with increased information density. In order to store greater amount of data, more transistors and capacitors are packed within a single chip, causing limited capacity and heat problems. The quest for more advanced memory technologies, lead to the finding of a volatile/non-volatile memory based on new architectures and materials such as molecular, macromolecular and ferroelectric memories. Most of the emerging non-volatile memories are based on two terminal switching elements which are good candidates for high-density memory architecture. However, current memory components show a single memory type with limited functionality (RAM, ROM, WORM etc.). The combination of more than one type of information storage, is advantageous for reading data in few different ways. For instance, combining a single bit with random access memory (RAM) and read only memory (ROM) may replace two individual transistors and therefore may reduce hardware size. Regarding the memory density challenge, a multilevel per bit memory chip is highly attractive, as it allows the storage of two bits of data per cell using four possible states.
In this work, a multilevel per bit organic memory cell (OMC) was demonstrated, the OMC can be read optically, to give write-once-read-many (WORM) memory, and can also be read electrically with read-while-writing memory type (RWW). The suggested memory-bit is composed of a multilayered nano-scale assembly of three metal organic complexes blocks, ruthenium, iron and osmium polypyridyl complexes. Integrating the bit into a conventional electronic circuit enables control over the charge state of the components individually, i.e. to switch between four different states based on charge trapping and release mechanism with step-wise release. The states are differing by their color as well as by their electronic properties. This results in a dual-function memory element that can be read in two separate ways: while RWW is based on electrical input and output, WORM is based on the distinct UV-vis transmittance of the OMC under the application of a certain voltage.
The states are defined by their color as well as by the charge of the state:
The working electrode (WE): indium thin oxide (ITO) coated PET (polyethylene terephthalate) is modified by the above mentioned polypyridyl complexes using alternatively spin coating PdCl2(PhCN)2 (4 mM, THF) and a solution of the metal-organic compound (6 mM, DCM:MeOH=1:1 v/v) as follows:
Ruthenium complex, electron mediator element, is attached to the conductive and transparent support by binding to a Pd linker layer to form a dense coordination network with palladium chloride. Ruthenium complex used as an electron monitoring agent that can facilitate or block electron transport through the entire molecular assembly.
On top of the ruthenium complex layer, iron- and osmium-polypyridyl complexes are deposited (respectively) in a block-like structure (see
The operation and mechanism of the OMC is as follow: the writing process starts from state 0.
However, the as-prepared bit [Ru]8[Fe]4[Os]4 is on state 3 where the components are in their divalent state. Therefore, application of 1.6 V is first needed for the components to be oxidized to initiate the memory operation (and to achieve state 0).
State 1 is written by application of 0.8 V, such that ruthenium complex is being reduced ([Ru]3+/2+) However, positive charge is stored on the upper blocks due to their lower oxidation potential. The ruthenium layer hamper electron transfer through the upper layers (iron- and osmium-based complexes) by physical isolation and electrically unfavorable reduction pathway. To write state 2, −1.4 V is applied, the ruthenium mediator is being reduced to its monovalent form and energy elevation of its reduction potential is observed (Ru1+/2+=−1.25 V), this oxidation state allows the ruthenium to facilitate electron transport towards the iron [Fe]3+/2+ but the osmium remain on its trivalent state (see
The read-out operation is divided into two orthogonal routes that show two different memory behaviors:
WORM memory: owing to the distinct optical properties of the states, one can read the implemented information by the optical signature of each individual state as many times as required using spectroscopic methods such as UV/vis absorption. The second memory behavior, (RWW), is based on the electrochemical difference between the states. In order to read out the information, 1.6 V is applied, and the amount of charge is calculated using chronoamperometry measurements (CA), while the bit is back to state 0. As the bit consists more divalent metal centers the read-out charge is higher and can stand as an indication for the identity of the state: state 1: 1 mc/cm2, state 2: 2 mC/cm2, state 3: 4 mC/cm2 and state 0 show no current upon 1.6 V.
Therefore, in some embodiments, optical detection is used to read the state of the device, and in some embodiments, the amount of charge is used to indicate the state of the device. In some embodiments both optical and electrochemical read outs can be used in parallel or sequentially for reading the state of the device/memory cell.
EDS-transmission electron microscopy (TEM) images (
Chronoamperometry and UV/vis absorption measurements demonstrated the OMC operation that included a random sequence of write-read voltages (
The OMC can be used to operate in a conventional circuit, the writing process is done by electronic hardware, a potentiostat, to implant the digital information, while the read-out is operated using electrical keyboard (see Figure). The keyboard follows the output voltage of the counter electrode (CE) during the erase/read voltage (1.6 V).
In order to read the information, a threshold voltage was determined at 1.94V (=Vth), and a LED is turned-on according to the time required for CE to reach back the 1.94 V (=Vth) on the way to 1.6 V (see
Cyclic voltammogram (CVs) measurement combined with UV/Vis spectroscopy, were used to examined the charge trapping phenomenon: the as-prepared hybrid bit is on state 3 (bordeaux appearance) repetitive cycling of the potential between 0 V and 2 V has been performed, resulting in charge trapping on both the iron and the osmium blocks. The evidence for charge trapping is provided by the irreversible oxidation of the upper layers ([Fe]2+/3+ and [Os]2+/3+) whereas the ruthenium complexes can be reversibly addressed ([Ru]2+/3+) The oxidation of the assembly exposes two main peaks instead of three (one for each component). The osmium layer is isolated with respect to the electrode, therefore, in order to address the upper layer, an electron channel from the electrode should appear; traces of [Ru]3+ and [Fe]3+ can mediate the oxidation of the osmium layer. When the oxidation potential of the ruthenium block is 1.3 V vs. Ag/Ag+, traces of [Ru]3+ starts to appear at 1.0 V (the onset potential) and overlaps with the onset potential of the iron layer, which in turn, can charge (oxidize) the osmium layer. As a result, one peak is obtained (at 1.1 V vs. Ag/Ag+) representing the oxidation of both iron and osmium. The CV shows that only ruthenium complexes are being reduced when a scan from 2 V−0 V is conducted after the first redox cycle, the ruthenium mediator is on its divalent state (═Ru2+) and stands as an insulator that blocks electron transfer towards the upper layers (state 1). Spectroelectrochemical measurements were monitored at λmax=500 nm and showed the dramatic increase in transmittance value (20% to 65%) upon oxidation, the metal to ligand charge transfer (MLCT) becomes prohibited and ligand charge transfer (LCT) becomes dominant therefore, state 0 appeared transparent, whereas upon reduction (2 V−0 V) state 1 is achieved (38% transmission) and the characteristic orange color of the ruthenium appeared.
Spectroelectrochemistry (SEC) measurement of the bit under ten consecutive read-write voltage cycles was shown and revealed the performance of the OMC with significant difference of the states. Optical write cycle stability at λmax=500 nm: 0: 0.2, 1: 0.42 2: 0.55 3: 0.65. Remarkably, continued write-read cycles showed the optical stability of the OMC with 80% degradation after 80 cycles for state 1, 75 cycles for state 2 and 25 for state 3. The electrical stability calculated as mentioned above, revealed 85% degradation after 50 write-read cycles for state 1, 70 for state 2 and 50 for state 3. The area under the read-out peak clearly reflects the amount of charge that passed the working electrode as well as the time required in order to achieve complete oxidation (RWW memory,
The suggested OMC showed a dual function memory behavior based on the deposition of electrochromic redox active species on top of a conductive support. Application of various potentials caused changes in the metal center oxidation state (M0-+3). The oxidation state—color coupling, combined with the distinct charged state allows to read out the information by optical measurement (WORM) as well as by an electrochemical approach (RWW). The deposition sequence and the architecture of the thin film set-up were strictly selected and afforded charge trapping on the upper layer and step wise release in response to an external voltage.
It is to be noted that a large range of other combinations of different metal ions and a large range of combinations for the construction sequence of the metal-ion organic complex multilayer blocks can be used to achieve organic memory cells with varying charge properties, varying optical properties, and with a variety of number of states for the memory cell. A memory cell/data storage device of this invention can be designed to include different ions, different thicknesses for each ion block, different sequence for the construction of the various blocks (i.e. which block is closer to the electrode, which block is constructed first/last/in the middle/on top/below other blocks), different number of blocks, different surface area (electrode surface area) on which the multilayer is built etc. Such properties of the device can be modified in view of the number of states required, the charge and ion oxidation states involved and the optical spectrum of the various states of each ion.
Materials and Methods
Solvents (AR-grade) were purchased from Bio-Lab (Jerusalem), Frutarom (Haifa, Israel), or Mallinckrodt Baker (Phillipsburg, N.J.). Propylene carbonate (PC), poly(methyl methacrylate) (PMMA), PdCl2(PhCN)2, and trifluoromethyl-sulfonamide lithium salt were purchased from Sigma-Aldrich. Complexes 1-3 were prepared as reported. Indium-tin oxide-(ITO) coated poly(ethylene terephthalate) (PET) substrates (10 cm×10 cm, Rs=30Ω/□) were purchased from Xinyan Technology Ltd. (Hong Kong, China). The ITO/PET substrates were cleaned by immersion for 30 s in ethanol and acetone, and then dried under a stream of air. A Laurell spin-coater, model WS-400A-6NPP/LITE, was used for the formation of the molecular assemblies (MAs).
UV/Vis Spectroscopy. UV/vis spectra were recorded on a Cary 100 spectrophotometer. The absorbance was measured using the Cary Win UV-Scan application program, version 3.00 (182) by Varian (350 nm-800 nm). The transmittance was measured using the Cary WinUV-Kinetics application program, version 3.00 (182) by Varian. Bare substrates were used to compensate for the background absorption.
Electrochemical Characterization. Electrochemical experiments were carried out using a CHI660A or CHI760E electrochemical workstation. The following configuration of the electrochemical cell was used: ITO/PET (3 cm×3 cm, 0.5 cm×1 cm) served as the working electrode, Ag/Ag+ was used as the reference electrode, and a Pt wire was used as the counter electrode. Tetrabutylammonium hexafluorophosphate (TBAPF6) in ACN (0.1 M) was used as the supporting electrolyte. Spectroelectrochemistry measurements were performed in a N2-filled glovebox.
Focused Ion Beam (FIB) Microscopy. The lamella preparation was done using Dual beam FIB-SEM Helios 600. The images were taken at the surface of the samples and at cross sections that were milled with a 30 keV Ga+ FIB. The sample was first locally coated with a 150 nm-200-nm thick layer of platinum using electron-beam-assisted deposition, which was followed by the ion beam-assisted deposition of a 500 nm-600-nm thick layer of platinum. This coating protects the MA from ion-beam damage, providing a clean edge of the cross-section. HAADF (High angle annular dark field) STEM imaging and EDS measurement were done using Thermo Fisher Scientific Themis Z TEM which is double aberration-corrected and equipped with Super-X large solid angle x-ray detector for EDS. Measurements were done with acceleration voltage 200 kV.
Formation of the Molecular Assemblies (MAs). The MAs were obtained by iterative spin-coating of solutions of PdCl2(PhCN)2 (THF, 4.0 mM), and the ruthenium (1) iron (2) or osmium (3) complexes (CH2Cl2:MeOH=1:1 v/v; 0.6 mM). The PdCl2(PhCN)2 solution was drop-casted onto ITO/PET (3 cm×3 cm), the substrate was spun at 500 rpm for 10 s and then at 1000 rpm for 30 s. Next, a solution of complexes 1, 2 or 3 was drop-casted and the substrates were spun as described above. The substrates were then immersed in acetone for 30 s and were dried under a gentle stream of air. The deposition of PdCl2(PhCN)2 and of the metal complexes (1 or 2) are referred to as a single deposition cycle. For the formation of the MAs, first 6 or 8 deposition cycles with complex 1 were carried out. After immersing these MAs in acetone for 1 h, 4 deposition cycles were carried out with complex 2, followed by 4 deposition cycles of complex 3. The resulting MAs were immersed in ACN for 2 h and dried overnight under vacuum.
In this example two different functionalities of a metallo-organic film are described. The metallo-organic films are assembled on the surface of a transparent metal-oxide electrode. Two redox-active elements are included in the films:
With regards to the first property, electrochromism, it was found that the color of the material can be cycled for 1500 times from dark-purple to colorless by electrochemically addressing the Fe2+/3+ centers at 0.0-1.0 V (vs Ag/AgCl). The differences between the transmittance of these two states is high with ΔT=52%.
With regards to the catalytic activity of the palladium ion centers, it was found that water oxidation can occur by palladium oxide particles formed in-situ by applying a higher potential (1.22-2.0 V vs Ag/AgCl) resulting in the formation of hydrogen (H2) and oxygen (O2). The current density (product output) is stable for at least 7 hours in an aqueous electrolyte at pH=6.9 with faradaic efficiency (FE) of ˜70%.
Environmental sustainability requires a series of new functional materials for efficient catalysis, energy storage, conversion of solar energy into electricity, smart glass technology, carbon capture and isolation to name a few. Renewable-based energy solutions (i.e. solar, wind) need to be fully integrated with efficient energy storage and release systems. Electrocatalytic generation of hydrogen and oxygen from water is ideal as hydrogen can be used for energy storage. Hydrogen is transportable and can be used to process other storage chemicals such as liquid hydrocarbons. Molecular hydrogen is the ultimate clean fuel, since its combustion produces water only.
In 1982, the Meyer group reported ruthenium polypyridyl complexes as water-oxidation catalysts (WOCs). To date many other molecular catalysts have been reported, however, several issues hamper their large-scale utilization, including poor reusability and solubility of the catalysts, the need for sacrificial oxidants (e.g., ceric ammonium nitrate), and harsh (acidic or alkaline) reaction conditions. Additional limitations include slow reaction rates, low catalyst stability, and cost.
For a preferred system, low potentials are desired to drive the reaction with high current densities. In recent years, heterogenized catalysts on conducting surfaces have been shown to be chemically robust and reusable. Among various materials, transition metal oxides of ruthenium, iridium, manganese, cobalt and platinum and clusters thereof were widely studied for electrocatalytic water splitting. For example, the use of Pd—Mn3O4 and other catalytically-active nanoclusters have been reported. The optimization of the catalytic process also includes the search for suitable materials that can immobilize and stabilize the clusters. Recently, the use of polyethyleneimine-modified reduced graphene (rGO) was demonstrated to support bimetallic gold-palladium nanoparticles for electrocatalysis. Metal-organic frameworks (MOFs) have also been shown to be promising electrocatalysts. Using a perfluorinated polymer containing sulphonic acid groups (Nafion) as a binder, MOFs have been drop casted onto electrodes. Their high porosity allows the electrolyte and water molecules to access the catalytic sites. MOFs based on cobalt formed by atomic layer deposition were investigated for electrochemical water oxidation under alkaline reaction conditions. Another example of electrochemical water oxidation are MOFs doped with ruthenium catalyst as previously reported.
Multilayers and devices shown in this example are based on series of nanoscale metallo-organic assemblies (molecular assemblies MAs) that are redox-active, thermally stable and highly porous. Coordination-based networks comprised layers of polypyridyl complexes and metal salts have been generated on transparent conductive oxide (TCOs) using Layer-by-Layer (LBL) assembly by automated spray-coating or spin-coating. In previous work, whereas the polypyridyl complexes were the functional components, the metal salts (mainly palladium) functioned as a crosslinker binding to pyridyl moieties of polypyridyl complexes to generate 3D networks. The large structural versatility of this class of MAs resulted in diverse and potentially useful functions: interlayers for efficient inverted bulk-heterojunction solar cells, mimicry of logic gates and circuits (including flip-flops), memory elements, supercapacitors, anti-bacterial coatings, and directional electron transfer. Furthermore, these materials have excellent charge trapping and multistate electrochromic characteristics. However, the electrocatalytic properties of such MAs has not been explored.
In this example, the combination of electrochromism and electrocatalytic water splitting was demonstrated. Both electrochromism and catalysis are performed in an aqueous electrolyte, and the electrocatalytic water splitting is performed using a single functionalized electrode under mild reaction conditions. The demonstration of electrochromism in water is advantageous for the development of laminated devices in which no volatile organic solvents need to be used. The MAs used in this example have been prepared using fully-automated layer-by-layer (LbL) spin-coating.
The system used herein is based on two functional components:
The coordination of three pyridyl moieties of the iron complex with palladium (II) salt forms a dense, but still porous network. This network is fabricated on fluorine-doped tin oxide (FTO) coated glass. The coordinatively-saturated iron(II) complex has excellent electrochromic properties. It is deeply colored (purple) in the ground state and becomes highly transparent in the visible region upon one-electron oxidation, because of the unfavorable metal-to-ligand charge transfer (MLCT) in the formed iron(III) complex. This one-electron redox process (Fe2+/Fe3+) is reversible.
The palladium entity catalyzes water splitting to generate hydrogen and oxygen without the need for sacrificial materials. The interface engineering of the FTO electrodes is a multi-step process that is conveniently carried out using fully automated spin-coating. The assembly of the different components on the surface is sufficiently fast that the sequential steps can be carried out without significant delay times.
As discussed above, the MA-modified electrodes operate as anodes in two distinctly different electrochemical processes that occur in water under neutral conditions.
In the electrochemical water splitting cell (EWSC) water is converted to oxygen at the MA-modified anode and hydrogen evolves at a platinum cathode.
The MA was prepared by alternatively spin-coating solutions of PdCl2(PhCN)2 (4.0 mM, THF) and the polypyridyl iron complex (1: 0.6 mM, DCM:MeOH=1:1 v/v) on FTO/glass (2 cm×2 cm). This fully automated deposition sequence was repeated 15 times and included washing steps with common organic solvents. This protocol resulted within 70 minutes in an electrode having both the desired electrochromic and catalytic properties. The electrodes are visually homogenously coated by the dark purple MA. Such assemblies prepared by LbL dip-coating, automatic spray-coating or by manual spin coating are known to have excellent electrochromic properties in non-aqueous electrolyte solutions of acetonitrile. The number of depositions can be used to control the color intensity of the films.
A three-electrode cell configuration have been used consisting of MA/FTO/glass as the working electrode (=anode) and Pt and Ag/Ag+ wires as the counter and quasi-reference electrodes, respectively. An aqueous solution of LiClO4 (0.1 M) was used as electrolyte with pH 6.9. Cyclic voltammetry (CV) measurements recorded with a scan rate of 0.1 V/s showed reversible redox processes at 0.69 V and 0.44 V with half wave redox potentials, E1/2, of 0.56 V (versus Ag/AgCl; 0.1 M LiClO4/H2O). These observations are indicative for a Fe2+/3+ redox couple. These redox processes occur under lower potentials in comparison to the use of organic media. CV measurements were performed at different scan rates (0.1-0.9 V/s). Clear exponential and linear correlations (R2>0.99 for all fits) were observed between the peak currents and scan rates and the square root thereof. These correlations indicate that the redox processes are diffusion controlled. The diffusion coefficient, Df, for MA1 is ˜3.7×10−8 cm2·s−1 for both the oxidation and reduction processes. This value was calculated using the Randles-Sevcik equation.
Spectroelectrochemical (SEC) measurements recorded in the transmission mode show the characteristic, broad metal-to-ligand charge-transfer (MLCT) band of the iron(II) complex at λmax≈575 nm. The MLCT band disappears upon the one-electron oxidation of the Fe2+ centers. This redox process is fully reversible and is accompanied by color-colorless-color transitions, as clearly observable by the naked eye. The high transparency of the MA upon applying an oxidative current indicates that all metal centers are electrochemically addressable at the applied scan rate.
To demonstrate the reversibility of this redox process in water, alternating potentials of 0.0 V and 1.0 V were applied with time intervals of 3 sec. while simultaneously montoring the optical absorbance of the MA at λmax=575 nm. These SEC measurements show that the maximum ΔT % of ˜52% is achieved in ˜0.9 s with ≥97% retention of the initial ΔT % for at least 1500 cycles. The coloration efficiency is estimated to be ˜155 cm2/C. The electrochromic properties of such assemblies are not affected by the use of aqueous electrolyte solutions.
The above-demonstrated electrochromic functionality occurs at potentials that are lower than the potential required for electrocatalytic water splitting. Upon increasing the potential higher than 1.22 V, catalytic oxidation of water occurs as indicated by the formation of bubbles on the surfaces of the colorless MA (active surface are λmax=2.4 cm2) and the Pt wire. The CV indicates oxygen evolution by the increase of the catalytic wave. The catalytic current is significantly higher than observed for bare FTO/glass. The corresponding Tafel plot shows a slope of 230 mV dec-1 as has been observed for electrocatalysis by MOFs. Electrolysis at a constant potential of 1.75 V (vs Ag/AgCl) show a gradually increasing current density until a plateau was reached (1.5 h) and a current density of ˜7.2 mA/cm2 was retained for an additional 5.5 h. Also in this experiment, bare FTO/glass displayed a much lower (=fourfold) catalytic current under the same conditions. Gas chromatography (GC) analysis of the gas mixture in the headspace of the working compartment of the airtight electrochemical cell confirmed the formation of 537 μmol of H2 after 4.5 h reaction time (≈268.5 μmol of O2). Controlled potential electrolysis (CPE) indicated that 148 C of charge passed, corresponding to a faradaic efficiency (FE) of 70%. The turnover frequency (TOF) was found to be 0.12 s−1. Anodization has been observed by others and indicate an electrochemically-driven process to activate the catalyst. The initial anodization process of ˜1.5 h markedly improved the catalytic activity and can be associated with structural changes within the films. The catalytic current was not seemingly affected when replacing the electrolyte solution after 6 h of electrolysis, and continuing the experiment with the same MA for additional 8 h. Therefore, changes in the electrolyte solution or the build-up of H2 and O2 appear not to play a role in the efficiency of the catalytic process. Under the applied oxidative conditions in water, palladium oxide particles are expected to form as has been indicated by scanning electron microscope measurements (SEM, vide infra).
To rigorously exclude the role of the polypyridyl iron complex (1) in the water oxidation, we functionalized FTO electrodes with MA2 without this electrochromic component. A solution of PdCl2(PhCN)2 (4.0 mM, THF) and the vinylpyridyl ligand L (2.0 mM, DCM:MeOH=1:1 v/v) were spin-coated on FTO/glass (2 cm×2 cm) using fully automated spin-coating (see herein below: “Formation of molecular assemblies (MA1 and MA2)” for details). This deposition sequence was repeated 15 times. UV-Vis spectroscopy show a linear growth process as seen by plotting the absorption intensity at λmax=333 nm versus the number of deposition cycles. CV measurements recorded under the same conditions as for MA1 did not show the oxidation and reduction peaks that have been attributed to complex 1. The observed onset potentials and catalytic currents are similar to the values observed with MA1. The Tafel slope of 217 mV/dec and current density from CPE at a constant applied potential of 1.75 V vs Ag/AgCl during 7 h are also similar. Bubbles are clearly observable at the working and counter electrodes. GC analysis of the gas mixture indicated that 896 μmol of H2 was produced (≈448 μmol of O2) after 6.5 h. CPE indicated that 264 C of charge passed for an active surface area of 2.4 cm2, corresponding to a faradaic efficiency (FE) of 67%. An anodization process similar to the one observed for MA1 was observed here as well. These observations are evidence that the role of complex 1 is limited to electrochromism, and indicate that the palladium component is catalyzing the water splitting for both MAs.
An obvious question is whether or not palladium nanoparticles are being formed that operate as water splitting catalyst. Scanning electron microscopy (SEM) is an excellent tool for the detection of palladium(0) nanoparticles as small as ø=8 nm in metallo-organic films. In this method, oxidative potentials are being used, therefore the formation of metallic particles is not expected. However, it is known that palladium salts can form particles of palladium oxides under oxidative potentials in water. SEM imaging was performed on the two MAs before and after electrocatalysis for 7 h. These measurements show the presence of grainy, continuous coatings after electrocatalysis. After electrocatalysis, the presence of small amounts of particles has been observed. Redox cycling (0V to 1V) (×1500) does not alter the texture and no such particles were observed (
X-ray photoelectron spectroscopy (XPS) was used to study the elemental composition and the metal oxidation states of the upper 15-20 nm of both MAs before and after 7 h of electrolysis. For MA1, two distinctive peaks attributed to the 2p orbitals of Fe2 were observed at 708 eV (2p3/2) and 720 eV (2p1/2). The binding energies did not change and no peaks indicating the formation of iron oxides were present. The overall oxidation state (2+) of the palladium is also not affected, but the peaks of the 3d orbitals are slightly shifted from 337 eV (3d5/2) and 342 eV (3d3/2) to 338 eV (3d5/2) and 343 eV (3d3/2). These shifts can indicate an exchange of Cl− with ClO4− which is present in excess in the electrolyte solution and are consistent with the formation the palladium oxide particles as suggested by SEM. The amount of Cl− is significantly reduced and ClO4− is observed. Changes in the oxidation state of the palladium centers during the reaction is likely facilitating this anion exchange. XPS analysis of MA2 show a similar effect.
This example highlights the electrochromic performance of metallo-organic films in an aqueous electrolyte without sacrificing switching stability and optical properties as compared to organic electrolytes. These findings can eliminate the use of volatile organics in sol-gel devices and can be a new entry to the application of non-toxic chemicals in electrochromics and electronic devices based on metallo-organic films. Moreover, the films formed in this example were demonstrated to have orthogonal properties. By applying different potentials, water splitting under mild (neutral) conditions occurs, indicating that such materials are promising for electrocatalysis. Mechanistically, the anodization process is consistent with the formation of nanosized particles that have been observed experimentally. The exact structure of these particles is yet unknown but it is expected that these particles are palladium oxides formed under the applied oxidative conditions in water. Although supporting evidence for the formation of such nanoparticles was obtained, it is experimental unproven if the water splitting occurs exclusively by those particles. Another interesting observation is the correlation between the catalytic performance and the number of deposited layers, and the similarity between the different molecular assemblies (MA1/MA2) as seen from cyclic voltammetry measurements. For both assemblies, the catalytic performance increases for up to 10 layers, and subsequently levels off upon increasing the thicknesses of the assemblies. Although several factors are likely contributing to this effect, it was noticed that these structurally different assemblies have indistinguishable surface texture and roughness. It is most likely that the molecular assembly-water interface plays a dominant role, as is an established fact for many heterogeneous catalysis systems. To this end, this first study shows that the performance of the disclosed MAs is comparable to other MOFs on surfaces.
It is to be noted that catalyst ions other than Pd can be used in embodiments of this invention. Further, catalysis of processes other than water splitting can be addressed using multilayer catalysts of this invention. In some embodiments, the catalysts of this invention include in addition to the catalytic ion (e.g. the Pd ion), an electrochromic entity (e.g. the Fe ion center as noted above or a different metal ion with electrochromic properties). In some embodiments, no electrochromic entity is present and the multilayer comprises the ion (e.g. Pd) that provides the catalytic activity, a ligand to bind to the catalytic ion to form a multilayer and no additional electrochromic entity (e.g. no electrochromic iron ion).
Materials and Methods
Solvents (AR-grade) were purchased from Bio-Lab (Jerusalem), Frutarom (Haifa, Israel), or Mallinckrodt Baker (Phillipsburg, N.J.). Lithium perchlorate (LiClO4) and PdCl2(PhCN)2 were purchased from Sigma-Aldrich. Fluorine-doped tin oxide-(FTO)-coated glass substrates (2 cm×2 cm, Rs=10Ω/□) were purchased from Xinyan Technology, Ltd. (Hong Kong, China). The FTO-coated glass substrates were cleaned by sonication in ethanol for 10 min, dried under a stream of N2, and subsequently cleaned for 20 min. in a UVOCS cleaning system (Montgomery, Pa.). The substrates were then rinsed with tetrahydrofuran (THF), dried under a stream of N2, and oven-dried at 130° C. for 2 h. A Laurell automatic spin-coater, model WS-65MZ-8NPPB, was used for the formation of the molecular assemblies (MAs).
UV/Vis Spectroscopy. UV/Vis spectra were recorded on a Cary 100 spectrophotometer. The absorbance was measured using the Cary Win UV-Scan application program, version 3.00 (182) by Varian (200 nm-800 nm), whereas the transmittance was measured using the Cary Win UV-Kinetics application program, version 3.00 (182) by Varian. Bare substrates were used to compensate for the background absorption.
X-ray Photoelectron Spectroscopy (XPS). XPS measurements were carried out with a Kratos AXIS ULTRA system, using a monochromatic Al Kα X-ray source (hυ=1486.6 eV) at 75 W and detection pass energies ranging between 20 eV and 80 eV. Curve-fitting analysis was based on Shirley or linear background subtraction and the application of Gaussian-Lorenzian line shapes.
Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) mapping. SEM images of [MA IFTO/glass] (1.0 cm×1.0 cm) were recorded using a The Zeiss Sigma 500, operating at 5 keV. Images were collected in secondary and backscattered electron modes by using In-Lens detectors, respectively. The aperture size was 30 microns. The SEM-energy-dispersive X-ray spectroscopy (EDS) mapping was performed by using EDS Bruker XFlash/60 mm at accelerating voltages of 10 kV. The aperture size was 60 microns.
Gas chromatography (GC) analysis. HP 6890 Series GC System; column: SUPELCO 1-2382, 5 Ft×⅛ In S.S. SUPPORT 45/60 CARBOXEN™ 1000, Packed Column. Inlets: 87° C., Detector: TCD 250° C.; Carrier Gas: He; Flow: 29.1 mL/min; Oven: 35° C., hold 2 min; 10° C./min to 60° C., hold 0 min; 30° C./min to 200° C.
Electrochemical characterization. The oxygen evolution reaction (OER) measurements were carried out using a CHI760E electrochemical workstation. The following configuration of the electrochemical cell was used: working electrode MA1 or MA2 on FTO/glass, reference electrode: Ag/AgCl, and the counter electrode: Pt wire. Lithium perchlorate (LiClO4, 0.1 M) in H2O was used as the supporting electrolyte (pH≈6.9). Cyclic voltammetry (CV) was performed at a scan rate of 0.1 V. The function, η=a+b log j, was used to extract the Tafel slope, b(V dec−1). The overpotential and current density are presented by η(V) and j(A cm−2), respectively.
Formation of molecular assemblies (MA1 and MA2). The MAs were formed by using an automated spin coater equipped with three syringes containing PdCl2(PhCN)2 and complex 1 or ligand L: (syringe 1) PdCl2(PhCN)2 (4.0 mM) in THF, (syringe 2) complex 1 (0.6 mM) or ligand L (1.8 mM) in DCM/MeOH (1:1 v/v), and (syringe 3) acetone for washing, respectively. The solution of PdCl2(PhCN)2 was drop casted (0.7-0.8 mL, syringe 1) onto FTO/glass (2 cm×2 cm), subsequently, the substrate was spun at 500 rpm (acceleration 250 rpm/s) for 10 s and then at 1000 rpm (acceleration 500 rpm/s) for 30 s. Next, a solution of complex 1 or ligand L was drop casted (0.7-0.8 mL, syringe 2) after 80 s on the substrates, which was spun as above. Finally, acetone was drop casted after 80 s (syringe 3) and spun for 40 s at 1000 rpm (acceleration 500 rpm/s). The PdCl2(PhCN)2/1 or PdCl2(PhCN)2/L deposition steps are referred to as a single deposition cycle. The deposition cycles were repeated 15 times.
Onset overpotential=Onset potential−Thermodynamic potential
Onset potential=1.22 V(vs Ag/AgCl)
Thermodynamic potential=E0−0.059pH, (where E0=1.23V,pH≈6.9)
Therefore, the onset overpotential:η=E(Ag/AgCl)−[E0−0.059pH]=0.397 V
Turnover Frequency (TOF) Calculations from CV.
TOF=J/(nFC)
Where, the current density, J=4.27 mA cm−2, number of transferred electrons per catalytic site, n=4, Faraday constant, F=96485 C mol−1, and CFe is the number of estimated electrochemically active iron centers. CFe=Q/F=3.5 mC cm−2/96485 mol C−1=3.6×10−8 mol cm−2. The ratio of Pd/Fe=2.5 (from XPS), therefore the total number of Pd centers (CPd)=9×10−8 mol cm−2. Therefore, TOF=0.12 s−1
Turnover Frequency (TOF) Calculations after Electrolysis.
TOF=amount of H2 produced after electrolysis/catalytically active metal sites(C)×time(s)=0.18s−1
Catalytically active metal sites=18×10−8 mmol(9×10−8 mol cm−2×2 cm2)
FE=η(O2)Exp/η(O2)Theor
The theoretical value (η(O2)Theor) was determined from controlled potential electrolysis (CPE) measurements for MA1 using the following reaction condition. Electrocatalysis was performed in a solution of 0.1 M LiClO4 (pH≈6.9) at 1.75 V vs. Ag/AgCl. The total charge (Q) was 148 C for a time period of 4.5 h. The active surface area=2 cm×1 cm. The number of electrons passed can be derived from: Q/e−=148/1.6×10−19=92.5×1019. The formation of one molecule of O2 requires 4 electrons, therefore 92.5×1019/4=23.1×1019 molecules of O2 are formed (assuming a yield of 100%). One mole=6.023×1023 molecules, therefore: η(O2)Theor=383 μmol.
Experimental values, η(O2)Exp, calculated by quantification of the amount of H2 gas.
Quantitative gas evolution measurements: In order to quantify the evolved gas (H2 and O2) over time, bulk electrolysis at 1.75 V (vs Ag/AgCl) has been carried out using a custom-designed gas-tight catalytic cell (
Determination of η(O2)Exp
For the quantification of H2, the calibration curve showed in
FE=η(O2)Exp/η(O2)Theor=268.5/383=70%
It was found from CPE that 448 μmol of O2 was formed with 264 C of charge passed for 6.5 h of electrolysis at 1.75 V (vs Ag/AgCl), corresponding to a FE of 67% The active substrate area=2.4 cm2.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IL2021/050694 | 6/9/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16896266 | Jun 2020 | US |
| Child | 18000826 | US |
