This application claims the benefit of priority of Taiwan Application Number TWI 11127996, filed Jul. 26, 2022, which is herein incorporated by reference in its entirety.
The present invention is related to a metal-free perovskite film and metal-free perovskite piezoelectric nanogenerators, and particularly to an MDABCO-NH4I3 film and MDABCO-NH3 piezoelectric nanogenerators.
Recently, there are many designs utilizing halide perovskites with excellent piezoelectricity to make piezoelectric devices, such as piezoelectric nanogenerators and piezoelectric sensors. However, current halide perovskite nanogenerators still have the following problems needed to be overcome: relatively poor output performance in application and presence of toxicity. Thus, it is still difficult to broadly apply them into biomedical field.
Replacing lead ions by tin has been reported in several studies so far to generate eco-friendly and non-toxic halide perovskite piezoelectric nanogenerators. However, the poor stability of the equipment is still a critical problem to be solved. Also, wearable electronic products applying halide perovskites are still quite rare.
In view of the deficiencies and drawbacks of the prior art, the present invention synthesizes a metal-free perovskite film and a metal-free perovskite piezoelectric nanogenerator which is metal-free, stable and non-toxic and can be applied in biochemical energy-harvesting devices, self-powered sensors, human-machine interfaces and wearable treatment apparatus.
Accordingly, the present invention provides a metal-free perovskite film characterized in that:
formula of the metal-free perovskite is ABX3, wherein A is MDABCO2+; B is ammonium cation; X is halide anion: and the metal-free perovskite is free from lead.
Furthermore, the halide anion is chloride ion, bromide ion, or iodide ion.
Furthermore, the film is prepared with metal-free perovskite precursor with a concentration of 0.25M˜1M.
Furthermore, preheating temperature for substrate is in a range from room temperature to 140° C.
Furthermore, the film has a piezoelectric constant of 1˜179 μm/V, preferably 5˜35 μm/V, more preferably 12.81 μm/V.
Furthermore, the film has a remnant polarization of 1˜22 μC/cm2, preferably 5˜14 μC/cm2, more preferably 13.3 μC/cm2.
The present invention also provides a metal-free perovskite piezoelectric nanogenerator characterized by comprising the said metal-free perovskite film.
Furthermore, it comprises flexible substrates, electrodes, conductive polymer layers, piezoelectric material layers and passivation layers.
Furthermore, the nanogenerator has an open-circuit voltage of 9˜16 V.
Furthermore, the nanogenerator has a short-circuit current of 38˜55 nA.
The open-circuit voltage of the MDABCO-NH4I3 piezoelectric nanogenerator of the present invention may reach 9˜16 V and the short-circuit current may reach 38˜55 nA.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention may change output according to applied strain and therefore can be applied in devices such as intelligent human-machine interface platform.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention has excellent stability, that is, the device can withstand over 5000 bending cycles without significant degradation.
The MDABCO-NH4I3 material of the present invention is free from lead. Thus, it is non-cytotoxic for L929 fibroblasts and it is also a kind of eco-friendly and non-toxic material.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention has the effect of significantly promoting cell proliferation and enhancing cell migration.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention can be used as self-powered strain sensor with high sensitivity and reliable feedback ability.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention has the effects of being able to light up a commercial LED, charging a capacitor, and serving as a self-powered strain sensor for an intelligent human-machine interface platform.
The MDABCO-NH4I3 piezoelectric nanogenerator of the present invention can be designed as an in vitro electrical stimulation device and applied as a portable wound healing system.
With respect to the cytotoxicity of MDABCO-N4I3 materials,
The performances of the metal-free perovskite film and metal-free perovskite piezoelectric nanogenerators of the present invention are illustrated by the following detailed description and examples. It should be noted that the following detailed description and examples are only used to describe the present invention, but not to limit the scope the present invention.
[Synthesis of MDABCO-NH4I3 Crystals].
The experimental procedure is as follows.
First, 1.84 g (15.57 mmol) of 1,4-diazabicyclo[2.2.2]octane (DABCO, 95%. KANTO) was dissolved in 20 nL of acetone (99%, Union Chemical Works Ltd.) and stirred in an ice bath, then 1 mL (15.57 mmol) of iodomethane (CH3I, 95%, Showa Chemical Co. Ltd.) is slowly added for methylation reaction. The white precipitate of methylated DABCO (i.e., MDABCO-I) was then collected and dried. Subsequently, 3.96 g (15.57 mmol) of MDABCO-I was dissolved into 20 mL DI water and stirred in an ice bath. 3.5 mL (26.51 mmol, overdose) of hydriodic acid (HE, 57%, Alfa Aesar) was then slowly added for the protonation reaction.
Then, the precipitate of MDABCO-I2 was formed and rinsed by methanol and acetone to remove excess hydriodic acid until the color of the precipitate became white or slightly yellow. The MDABCO-I2 was then dried up and recrystallized for 1 time without further purification.
1 mmol of MDABCO-I2 and 1 mmol of NH4I (99%, Union Chemical Works Ltd.) were dissolved in 20 mL DI water and slowly evaporated at 55° C. to form the MDABCO-NH4I3 crystals.
While Iodide ions are used as the halide anions in this example, it is not limited to this. Chlorine ions and bromine ions with similar chemical properties with a valency of −1 can also achieve the same effect as iodide ions.
The MDABCO-NH4I3 film of the present invention is illustrated by the following exemplary examples.
Preparation of Poly(3,4-Ethylenedioxythiophene):Poly(Styrenesulfonate) (Abbreviated as PEDOT:PSS) Films:
PEDOT:PSS (Clevios PH1000) was first filtered and mixed with 2 vol % of dimethyl sulfoxide (DMSO, 99%, Acros Organics) and 0.05 wt % of Triton X-100 (99%. Alfa Aesar). 200 μL of the PEDOT:PSS solution was then spin-coated on the polyimide (PI) substrate at 1000 rpm for 15 s. The sample was then annealed under 120° C. for 10 minutes. PEDOT:PSS films in Example 1˜7 are prepared with the aforementioned method respectively. The area and the thickness of the PEDOT:PSS film were 1.5×1.5 cm2 and 75 nm, respectively.
Preparation of MDABCO-NH1I3 Films:
Various MDABCO-NH4I3 precursor solutions with concentrations of 0.25 M, 0.5 M, 0.75 M, and 1 M were prepared by dissolving 0.133 g (0.25 mmol), 0:266 g (0.5 mmol), 0.398 g (0.75 mmol), and 0.531 g (1 mmol) of MDABCO-NH4I3 crystals into 1 mL deionized water, respectively.
Furthermore, the MDABCO-NH4I3 film was prepared by using a hot-casting method: the PI substrate with PEDOT:PSS film prepared as previously described was preheated at “room temperature” for 10 minutes and quickly moved onto the spin-coater. 150 μL of 0.25 M, 0.5 M, 0.75 M, and 1 M MDABCO-NH4I3 solution was dropped onto substrate and spin-coated under 3000 rpm for 15 s. After spin-coating, the film was annealed under 80° C. for 10 minutes to get MDABCO-NH4I3 films in Examples 1˜4.
Also, the metal-free perovskite films of the present invention can be prepared by not only spin-coating as previously described, but also spraying, inkjet printing, physical vapor deposition and chemical vapor deposition.
The MDABCO-NH4I3 films in Examples 5-7 were prepared with preheating temperature of PI substrate with PEDOT:PSS film in Example 3 (i.e. 0.75 M MDABCO-NH4I3 solution) changed from “room temperature” to 100° C., 120° C., and 140° C. respectively and other conditions remained the same.
[Synthesis of MDABCO-NH4I3 Piezoelectric Nanogenerators]
MDABCO-NH4I3 piezoelectric nanogenerator is consisted of flexible substrates, electrodes, conductive polymer layers, piezoelectric material layers and passivation layers. The material of flexible substrates can be selected from polyethylene terephthalate, polyimide, polypropylene, polyether sulfone, polyvinyl chloride and polytetrafluoroethylene. The material of electrodes can be selected from metals, conductive oxides and conductive nitrides and the combination thereof. The conductive polymer layers can be selected from polyaniline, polypyrrole, polythiophene, poly(p-phenylene vinylene) and copolymer or mixture of the above polymers. The piezoelectric material layers are metal-free perovskite layers, MDABCO-NH4I3 films. The passivation layers are poly(dimethylsiloxane) (PDMS) and can be used to connect the electrodes. The experiment methods are as follows.
First, 100 nm of Ag was deposited on two pieces of PI substrates each with an area of 2×6 cm2 by a radio-frequency sputtering system (Kao Duen Technology Co.) to make top and bottom electrodes. In particular, Ag fully covered the top electrode, and PEDOT:PSS film was coated on PI substrates with 2×2 cm2 of Ag electrodes at the bottom electrode.
With the method preventing the reaction between Ag and halide ions, the MDABCO-NH4I3 solutions with the same condition as Example 7 (0.75M, preheating temperature: 140° C.) were deposited near the center of the substrate with 1.75×1.5 cm2 PEDOT:PSS film to form MDABCO-NH4I3 film with an area of 1.5×1.5 cm2.
Then, PDMS resin (Sil-More Industrial Ltd.) was placed in 60° C. oven for 20 minutes to partially remove the ethylbenzene and then spin-coated onto the top electrode and partially dried at 60° C. for 20 minutes.
Also, the top electrode and the bottom substrate deposited with MDABCO-NH4I3 film, PEDOT:PSS and Ag were bonded through PDMS and cured in 60° C. oven for 2 hours.
As followed, the above MDABCO-NH4I3 films prepared in Examples 1˜7 are further illustrated and analyzed to explore the impacts of different precursor solution concentration and temperature and the piezoelectric properties.
[Properties of MDABCO-NH4I3 Films]
[Precursor Concentration and Preheating Temperature]
However, the surface of MDABCO-NH4I3 film becomes relatively nonuniform when the precursor concentration is 1 M. The reduced uniformity may be attributed to the viscosity increase with increased precursor concentration. Therefore, considering the trade-off between supersaturation and viscosity, it is selected to prepare MDABCO-NH4I3 film with precursor concentration of 0.75 M. In addition, it is also observed in
Also, the cross-sectional image of MDABCO-NH4I3 film prepared with precursor concentration of 0.75 M and preheating temperature of 140° C. is showed as
[Piezoelectric Properties]
As followed, the measured results of properties of MDABCO-NH4I3 film prepared with precursor concentration of 0.75 M and preheating temperature of 140° C. was further explored.
The values of polarization and coercive electric fields are estimated to be 13.3 μC/cm- and 30 kV/cm respectively based on ferroelectric current-voltage (I-V) and P-E curves in
Also, the phase response loop shown in
In addition, the piezoresponse hysteresis loop in
P(E)=A(E)cos[φ(E)] (1)
In Equation (1), P(E) is the piezoresponse, A(E) is the amplitude, and p(E) is the phase degree. The piezoelectric coefficient (d33) can also be estimated by using static sensitivity based quantification method. The average value of d33 is around 12.81 pm/V.
As followed, the MDABCO-NH4I3 piezoelectric nanogenerator described above is further illustrated and analyzed.
[MDABCO-NH4I3 Piezoelectric Nanogenerator]
[Configuration of the Device]
As the schematic illustration of the configuration of the device shown in
[Performance of the Device]
The output performance of the MDABCO-NH4I3 piezoelectric nanogenerator measured by an external mechanical system indicates that the device can provide periodic and controllable strain.
The result of applied strain versus output performances of the MDABCO-NH4I3 piezoelectric nanogenerator is shown in
In addition, as shown in
[Human-Machine Interface Application]
The present invention applies the self-powered sensing system of MDABCO-NH4I3 piezoelectric nanogenerator to human-machine interface. As shown in
Meanwhile, to further investigate the feasibility of using MDABCO-NH4IL piezoelectric nanogenerator in harvesting energy and detecting signals from localized physiological motions, the MDABCO-NH4I3 piezoelectric nanogenerator was utilized to record signals generated from human pulse, as shown in
Five gestures including “one,” “two,” “three” “four,” and “five” can be successfully displayed in real-time operation by obtaining the output voltage signals from the MDABCO-NH4I3 piezoelectric nanogenerators. The output signals were further transferred into a series of visualized symbols on computer interface denoted as yellow and black circles. The yellow circles represent the bending state, while the black circles represent the unbending state. Thus, body motion of humans such as gestures can be effectively translated into signals detectable for computers by applying MDABCO-NH4I3 piezoelectric nanogenerators. This application indicates that the MDABCO-NH4I3 piezoelectric nanogenerators are of great potential for future self-powered sensor and human-machine interaction platform designs. In addition, MDABCO-NH4I3 piezoelectric nanogenerators can also be further applied to various body parts such as knees, neck, eyelids, shoulders and can effectively translate the motion of various parts into signals detectable for computers.
[Cytotoxicity]
As described above, presence of lead is a critical factor which inhibits application of perovskite material on biomedical field, especially for skin electronics and in vivo sensing technology. According to the prior arts, it has been found that the higher concentration of perovskite material in culture medium for cells, the lower cell viability observed. Therefore, as shown in
Then, to assess the cytotoxicity of the as-synthesized MDABCO-NH4I3 material, a cell viability test has been conducted in films by using L929 fibroblasts. The result is shown in
[Cell Proliferation and Cell Migration]
Electrical stimulation therapy is a safe and convenient method for the treatment of several diseases, especially in regenerative medicine and neurology field related to wound healing, neuroplasticity, and neuro repairing. The reason is that endogenous electric fields can efficiently enhance cell proliferation and migration, providing the benefits for wound healing. Thus, the present invention confirms the potential of MDABCO-NH4I3 piezoelectric nanogenerator to be applied for cell proliferation and migration by studying the cellular behaviors of L929 fibroblasts under an electrical stimulation by MDABCO-NH4I3 piezoelectric nanogenerator.
According to
In summary, the MDABCO-NH4I3 film of the present invention prepared with precursor concentration of 0.75 M and preheating temperature of 140° C. exhibits the optimal distribution of compact and large grains. Therefore, MDABCO-NH4I3 piezoelectric nanogenerator applying the MDABCO-NH4I3 film has excellent performances.
However, as described above, films prepared with precursor concentration of 0.25 M˜1 M and preheating temperature for substrate of room temperature to 140° C. in Examples 1˜7 also show excellent distribution of compact and large grains, so they also have the effects of changing output according to the strains, having stability, withstanding over 5000 bending cycles without significant degradation, no cytotoxicity and significantly promoting cell proliferation and enhancing cell migration, and therefore may be applied in MDABCO-NH4I3 piezoelectric nanogenerator.
[Conclusion]
The present invention discloses the first fabrication of MDABCO-NH4I3 piezoelectric nanogenerator with metal-free perovskite MDABCO-NH4I3 film. The piezoelectric and ferroelectric properties of the MDABCO-NH4I3 film exhibit a piezoelectric constant of 12.81 μm/V and a remnant polarization of 13.3 μC/cm. After the poling process, the output voltage and current of the MDABCO-NH4I3 piezoelectric nanogenerator can reach 15.9V and 54.5 nA respectively.
In addition, MDABCO-NH4I3 piezoelectric nanogenerator has the effects of being able to light up a commercial LED, charge a capacitor, and serve as a self-powered strain sensor for an intelligent human-machine interface platform, demonstrating its feasibility and potential for practical electronics.
Furthermore, MDABCO-NH4I3 piezoelectric nanogenerator is also designed as in vitro electrical stimulation device, which is promising for portable wound healing system design. The results above all support the application of the MDABCO-NH4I3 film of the present invention in non-toxic, wearable, interactive, and multifunctional intelligent devices such as various application as shown in
[Testing Instruments and Methods]
The instruments and testing methods used in the present invention are described in detail as the follows.
[Analysis of Films]
The SEM images of the MDABCO-NH4I3 film were characterized by scanning electron microscope, JEOL JSM-7900F SEM, operated at an acceleration voltage of 5 kV.
The leakage current and ferroelectric hysteresis loop of the MDABCO-NH4I3 film were measured by Keithley 2612B sourcemeter on the samples coated with 50 nm of nickel as the top electrode (0.2×0.3 cm2).
PFM measurements were characterized by using a Bruker Dimension Icon Atomic Force Microscope under contact mode (with tunable LS PR AC bias, driving frequency is 15 kHz).
The amplitude and phase response loops were scanned with −10 to +10 V DC bias.
[Characterization of the MDABCO-NH4I3 Piezoelectric Nanogenerator]
The output characteristics of the MDABCO-NH4I3 piezoelectric nanogenerator were measured with Keithley 6514 electrometer (200 TΩ input impedance). A commercial linear mechanical system was used for providing controllable and periodically bending strain.
[MDABCO-NH4I3 Piezoelectric Nanogenerator-Cell Culture and Viability Test]
The L929 fibroblast cell line was purchased from Bioresource Collection and Research Center. Cells were maintained in Dulbecco's Modified Eagle Medium (DMEM, Corning) supplemented with 10% fetal bovine serum (FBS, Corning) and 1% antibiotic of penicillin-streptomycin solution (Corning) at 37° C. in a 5% CO2 incubator (BB15, Thermo Fisher Scientific). To investigate the cytotoxicity of MDABCO-NH4I3 material, 1×104 cells of L929 fibroblasts were seeded in a 96-well cell culture plate (Cat. No. 310109008, Thermo Fisher Scientific, MA, USA) and incubated at 37° C. in the 5% CO2 incubator overnight. Then, the media were replaced with various concentrations of MDABCO-NH4I3 and further incubated for 24 h. Cell viability was determined by the Cell Counting Kit-8 (CCK-8, Dojindo Laboratories, Kumamoto, Japan). The absorbance at the wavelength of 450 nm was measured by a microplate spectrophotometer (Multiskan GO, Thermo Fisher Scientific). Images of the cell morphologies were obtained by using an inverted optical microscope (Olympus CK30, Olympus).
[MDABCO-NH4I3 Piezoelectric Nanogenerator-Cell Proliferation and Migration]
1×10 cells of L929 fibroblasts were seeded in 35 mm diameter culture dishes for 24 h to investigate the impact of electrical stimulation from MDABCO-NH4I3 piezoelectric nanogenerator on cell proliferation. Cells were regularly stimulated at the frequency of 1 h/d.
Cell morphologies were obtained by using an inverted optical microscope (Olympus CK30). The cell proliferation rate was evaluated by Cell Counting Kit-8 at 24, 48, and 72 h. Cell migration was characterized by evaluating an in vino scratch assay. Cells were seeded in 35 mm diameter culture dishes (1×106 cells per dish) and grown at 37° C. in 5% CO2 incubator overnight. Confluent cells were maintained in DMEM containing 5% FBS. A straight scratch was made by using a sterile 1000 μL tip before electrical stimulation from MDABCO-NH4I3 piezoelectric nanogenerator. Cells were regularly stimulated at the frequency of 1 h/d. The scratched regions were recorded by an inverted optical microscope (Olympus CK30) and the areas were calculated by using the ImageJ software.
In particular, each experiment was repeated three tines in statistical analysis. The cell proliferation rate and the relative wound area were expressed as mean±standard deviation. The statistical analysis was performed by using the SPSS software. All results were analyzed by the two-tailed t-test, wherein p<0.05 was considered statistically significant.
Number | Date | Country | Kind |
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111127996 | Jul 2022 | TW | national |