Patent Application
20230101042
The present disclosure relates to compounds for use as emitters, and devices, such as organic light emitting diodes, including the same.
The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: Regents of the University of Michigan, Princeton University, University of Southern California, and the Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.
Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting diodes/devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.
OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.
Efficient emitters with high radiative rates are critical for high performance display technologies and solid-state lighting applications. Blue-emitting materials for OLEDs are particularly problematic due to the required high energy that leads to detrimental photophysical processes (TTA & TPA) and chemical decomposition of the materials. While decreasing the emission lifetime is key solutions to this issue, today's widely used heavy-metal phosphors (e.g Ir3+, Pt+2 complexes) inherently fail to have lifetimes below 1 μs due to the nature of spin-orbit coupling (SOC) contribution in the triplet harvesting events. That is, SOC that helps fast intersystem crossing events between singlets and triplets does eventually induce large zero-field splitting (ZFS) between triplet sublevels hampering fast equilibration of triplet states for harvest. Early developed organic and inorganic thermally activated delayed fluorescence (TADF) alternatives also suffer similar long-lived excitons (microsecond regime), but now due to the counteractive relationship between the required small singlet-triplet separation (ΔEST<0.12 eV) and large oscillator strength for short τTADF.
One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Alternatively the OLED can be designed to emit white light. In conventional liquid crystal displays emission from a white backlight is filtered using absorption filters to produce red, green and blue emission. The same technique can also be used with OLEDs. The white OLED can be either a single EML device or a stack structure. Color may be measured using CIE coordinates, which are well known to the art.
One example of a green emissive molecule is tris(2-phenylpyridine) iridium, denoted Ir(ppy)3, which has the following structure:
In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.
The present disclosure provides a compound of Formula (I):
wherein M1 is selected from the group consisting of Au(I), Ag(I), and Cu(I);
L is a carbene coordinated to the metal M1;
Z is a monoanionic ligand;
E1 is an electron accepting group;
n is an integer from 1 to the maximum allowable substitution on L, wherein when n is greater than 1, each E1 may be the same or different;
E1, L, and Z may each be substituted with one or more substituents independently selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
An OLED comprising the compound of the present disclosure in an organic layer therein is also disclosed.
A consumer product comprising the OLED is also disclosed.
Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.
The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.
More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.
More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.
The simple layered structure illustrated in
Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in
Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. Pat. No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink jet and organic vapor jet printing (OVJP). Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processability than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.
Devices fabricated in accordance with embodiments of the present invention may further optionally comprise a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from damaging exposure to harmful species in the environment including moisture, vapor and/or gases, etc. The barrier layer may be deposited over, under or next to a substrate, an electrode, or over any other parts of a device including an edge. The barrier layer may comprise a single layer, or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques and may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate an inorganic or an organic compound or both. The preferred barrier layer comprises a mixture of a polymeric material and a non-polymeric material as described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporated by reference in their entireties. To be considered a “mixture”, the aforesaid polymeric and non-polymeric materials comprising the barrier layer should be deposited under the same reaction conditions and/or at the same time. The weight ratio of polymeric to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be created from the same precursor material. In one example, the mixture of a polymeric material and a non-polymeric material consists essentially of polymeric silicon and inorganic silicon.
Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of electronic component modules (or units) that can be incorporated into a variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include display screens, lighting devices such as discrete light source devices or lighting panels, etc. that can be utilized by the end-user product manufacturers. Such electronic component modules can optionally include the driving electronics and/or power source(s). Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of consumer products that have one or more of the electronic component modules (or units) incorporated therein. A consumer product comprising an OLED that includes the compound of the present disclosure in the organic layer in the OLED is disclosed. Such consumer products would include any kind of products that include one or more light source(s) and/or one or more of some type of visual displays. Some examples of such consumer products include flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, mobile phones, tablets, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, camcorders, viewfinders, micro-displays (displays that are less than 2 inches diagonal), 3-D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screen, a light therapy device, and a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18° C. to 30° C., and more preferably at room temperature (20-25° C.), but could be used outside this temperature range, for example, from −40° C. to +80° C.
The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.
As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.
As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.
As used herein, “solution processable” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.
A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.
As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative) Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A “higher” HOMO or LUMO energy level appears closer to the top of such a diagram than a “lower” HOMO or LUMO energy level.
As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.
More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.
The terms “halo,” “halogen,” and “halide” are used interchangeably and refer to fluorine, chlorine, bromine, and iodine.
The term “acyl” refers to a substituted carbonyl radical (C(O)—Rs).
The term “ester” refers to a substituted oxycarbonyl (—O—C(O)—Rs or —C(O)—O—Rs) radical.
The term “ether” refers to an —ORs radical.
The terms “sulfanyl” or “thio-ether” are used interchangeably and refer to a —SRs radical.
The term “sulfinyl” refers to a —S(O)—Rs radical.
The term “sulfonyl” refers to a —SO2—Rs radical.
The term “phosphino” refers to a —P(Rs)3 radical, wherein each R can be same or different.
The term “silyl” refers to a —S1(Rs)3 radical, wherein each Rs can be same or different.
The term “boryl” refers to a —B(Rs)2 radical or its Lewis adduct —B(Rs)3 radical, wherein Rs can be same or different.
In each of the above, Rs can be hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combination thereof. Preferred Rs is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and combination thereof.
The term “alkyl” refers to and includes both straight and branched chain alkyl radicals. Preferred alkyl groups are those containing from one to fifteen carbon atoms and includes methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, and the like. Additionally, the alkyl group is optionally substituted.
The term “cycloalkyl” refers to and includes monocyclic, polycyclic, and spiro alkyl radicals. Preferred cycloalkyl groups are those containing 3 to 12 ring carbon atoms and includes cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[3.1.1]heptyl, spiro[4.5]decyl, spiro[5.5]undecyl, adamantyl, and the like. Additionally, the cycloalkyl group is optionally substituted.
The terms “heteroalkyl” or “heterocycloalkyl” refer to an alkyl or a cycloalkyl radical, respectively, having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si and Se, preferably, 0, S or N. Additionally, the heteroalkyl or heterocycloalkyl group is optionally substituted.
The term “alkenyl” refers to and includes both straight and branched chain alkene radicals. Alkenyl groups are essentially alkyl groups that include at least one carbon-carbon double bond in the alkyl chain Cycloalkenyl groups are essentially cycloalkyl groups that include at least one carbon-carbon double bond in the cycloalkyl ring. The term “heteroalkenyl” as used herein refers to an alkenyl radical having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Preferred alkenyl, cycloalkenyl, or heteroalkenyl groups are those containing two to fifteen carbon atoms. Additionally, the alkenyl, cycloalkenyl, or heteroalkenyl group is optionally substituted.
The term “alkynyl” refers to and includes both straight and branched chain alkyne radicals. Preferred alkynyl groups are those containing two to fifteen carbon atoms. Additionally, the alkynyl group is optionally substituted.
The terms “aralkyl” or “arylalkyl” are used interchangeably and refer to an alkyl group that is substituted with an aryl group. Additionally, the aralkyl group is optionally substituted.
The term “heterocyclic group” refers to and includes aromatic and non-aromatic cyclic radicals containing at least one heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Hetero-aromatic cyclic radicals may be used interchangeably with heteroaryl. Preferred hetero-non-aromatic cyclic groups are those containing 3 to 7 ring atoms which includes at least one hetero atom, and includes cyclic amines such as morpholino, piperidino, pyrrolidino, and the like, and cyclic ethers/thio-ethers, such as tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, and the like. Additionally, the heterocyclic group may be optionally substituted.
The term “aryl” refers to and includes both single-ring aromatic hydrocarbyl groups and polycyclic aromatic ring systems. The polycyclic rings may have two or more rings in which two carbons are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is an aromatic hydrocarbyl group, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. Preferred aryl groups are those containing six to thirty carbon atoms, preferably six to twenty carbon atoms, more preferably six to twelve carbon atoms. Especially preferred is an aryl group having six carbons, ten carbons or twelve carbons. Suitable aryl groups include phenyl, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene, preferably phenyl, biphenyl, triphenyl, triphenylene, fluorene, and naphthalene. Additionally, the aryl group is optionally substituted.
The term “heteroaryl” refers to and includes both single-ring aromatic groups and polycyclic aromatic ring systems that include at least one heteroatom. The heteroatoms include, but are not limited to O, S, N, P, B, Si, and Se. In many instances, O, S, or N are the preferred heteroatoms. Hetero-single ring aromatic systems are preferably single rings with 5 or 6 ring atoms, and the ring can have from one to six heteroatoms. The hetero-polycyclic ring systems can have two or more rings in which two atoms are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is a heteroaryl, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. The hetero-polycyclic aromatic ring systems can have from one to six heteroatoms per ring of the polycyclic aromatic ring system. Preferred heteroaryl groups are those containing three to thirty carbon atoms, preferably three to twenty carbon atoms, more preferably three to twelve carbon atoms. Suitable heteroaryl groups include dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof. Additionally, the heteroaryl group is optionally substituted.
Of the aryl and heteroaryl groups listed above, the groups of triphenylene, naphthalene, anthracene, dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, pyrazine, pyrimidine, triazine, and benzimidazole, and the respective aza-analogs of each thereof are of particular interest.
The terms alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aralkyl, heterocyclic group, aryl, and heteroaryl, as used herein, are independently unsubstituted, or independently substituted, with one or more general substituents.
In many instances, the general substituents are selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In some instances, the preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.
In some instances, the preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, sulfanyl, and combinations thereof.
In yet other instances, the more preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.
The terms “substituted” and “substitution” refer to a substituent other than H that is bonded to the relevant position, e.g., a carbon or nitrogen. For example, when R1 represents mono-substitution, then one R1 must be other than H (i.e., a substitution). Similarly, when R1 represents di-substitution, then two of R1 must be other than H. Similarly, when R1 represents no substitution, R1, for example, can be a hydrogen for available valencies of ring atoms, as in carbon atoms for benzene and the nitrogen atom in pyrrole, or simply represents nothing for ring atoms with fully filled valencies, e.g., the nitrogen atom in pyridine. The maximum number of substitutions possible in a ring structure will depend on the total number of available valencies in the ring atoms.
As used herein, “combinations thereof” indicates that one or more members of the applicable list are combined to form a known or chemically stable arrangement that one of ordinary skill in the art can envision from the applicable list. For example, an alkyl and deuterium can be combined to form a partial or fully deuterated alkyl group; a halogen and alkyl can be combined to form a halogenated alkyl substituent; and a halogen, alkyl, and aryl can be combined to form a halogenated arylalkyl. In one instance, the term substitution includes a combination of two to four of the listed groups. In another instance, the term substitution includes a combination of two to three groups. In yet another instance, the term substitution includes a combination of two groups. Preferred combinations of substituent groups are those that contain up to fifty atoms that are not hydrogen or deuterium, or those which include up to forty atoms that are not hydrogen or deuterium, or those that include up to thirty atoms that are not hydrogen or deuterium. In many instances, a preferred combination of substituent groups will include up to twenty atoms that are not hydrogen or deuterium.
The “aza” designation in the fragments described herein, i.e. aza-dibenzofuran, aza-dibenzothiophene, etc. means that one or more of the C—H groups in the respective aromatic ring can be replaced by a nitrogen atom, for example, and without any limitation, azatriphenylene encompasses both dibenzoniquinoxaline and dibenzoniquinoline. One of ordinary skill in the art can readily envision other nitrogen analogs of the aza-derivatives described above, and all such analogs are intended to be encompassed by the terms as set forth herein.
As used herein, “deuterium” refers to an isotope of hydrogen. Deuterated compounds can be readily prepared using methods known in the art. For example, U.S. Pat. No. 8,557,400, Patent Pub. No. WO 2006/095951, and U.S. Pat. Application Pub. No. US 2011/0037057, which are hereby incorporated by reference in their entireties, describe the making of deuterium-substituted organometallic complexes. Further reference is made to Ming Yan, et al., Tetrahedron 2015, 71, 1425-30 and Atzrodt et al., Angew. Chem. Int. Ed. (Reviews) 2007, 46, 7744-65, which are incorporated by reference in their entireties, describe the deuteration of the methylene hydrogens in benzyl amines and efficient pathways to replace aromatic ring hydrogens with deuterium, respectively.
It is to be understood that when a molecular fragment is described as being a substituent or otherwise attached to another moiety, its name may be written as if it were a fragment (e.g. phenyl, phenylene, naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g. benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or attached fragment are considered to be equivalent.
In some instance, a pair of adjacent substituents can be optionally joined or fused into a ring. The preferred ring is a five, six, or seven-membered carbocyclic or heterocyclic ring, includes both instances where the portion of the ring formed by the pair of substituents is saturated and where the portion of the ring formed by the pair of substituents is unsaturated. As used herein, “adjacent” means that the two substituents involved can be on the same ring next to each other, or on two neighboring rings having the two closest available substitutable positions, such as 2, 2′ positions in a biphenyl, or 1, 8 position in a naphthalene, as long as they can form a stable fused ring system.
Compounds of the Disclosure
In one aspect, the present disclosure relates to compounds of Formula I:
wherein M1 is selected from the group consisting of Au(I), Ag(I), and Cu(I);
L is a carbene coordinated to the metal M1;
Z is a monoanionic ligand;
E1 is an electron accepting group;
n is an integer from 1 to the maximum allowable substitution on L, wherein when n is greater than 1, each E1 may be the same or different;
E1, L, and Z may each be substituted with one or more substituents independently selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
In one embodiment, E1 is selected from the group consisting of a nitrogen-containing heterocyclic ring and a carbocyclic aromatic ring optionally having at least one electron-withdrawing substituent. In one embodiment, E1 is a nitrogen-containing heterocyclic ring selected from the group consisting of aza-dibenzothiophene, aza-dibenzofuran, aza-dibenzoselenophene, aza-benzofuran, aza-benzothiophene, aza-benzoselenophene, aza-carbazole, aza-indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, aza-xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, selenophenodipyridine, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof; wherein E1 is optionally further substituted. In one embodiment, E1 is a nitrogen-containing heterocyclic ring fused to the carbene L. In one embodiment, E1 is an aromatic ring having at least one electron-withdrawing substituent selected from the group consisting of halogen, pseudohalogen, haloalkyl, halocycloalkyl, heteroalkyl, amide, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein E1 is optionally further substituted.
In one embodiment, L is selected from the group consisting of Formula A, Formula B, Formula C, Formula D, Formula E, and Formula F:
wherein
each X1 to X4 independently represents NR1, CR1R2, C═O, C═S, O, or S; and
each occurrence of R1 and R2 is independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group;
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted.
wherein each X1 and X4 independently represents N, NR1, CR1, CR1R2, SiR1R2, PR1, B, BR1, BR1R2, O, or S; and
each X2 and X3 independently represents CR1, CR1R2, SiR1, SiR1R2, N, NR1, P, B, O, or S;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group;
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted; and
the dashed line inside the five-member ring represents zero or one double-bond.
wherein each X1 and X2 independently represents NR1, CR1R2, O, or S;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; and
wherein at least one substituent R1 and R2 comprises an electron accepting group;
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted.
wherein
each X1 to X5 independently represents N, P, NR1, PR1, B, BR1, CR1, SiR1, CR1R2, SiR1R2, C═O, C═S, O, or S;
n is 0 or 1;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group; and
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted;
wherein
each X1 and X4 independently represents NR1, CR1, SiR1, CR1R2, SiR1R2, PR1, BR1, C═O, C═S, O, or S;
each X2 and X3 is independently present or absent, and if present, independently represents H, NR1R2, CR1, CR1R2, C═O, C═S, O, or S;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group; and
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted
wherein each occurrence of X1 to X8 independently represents N, P, NR1, PR1, B, BR1, CR1, SiR1, CR1R2, SiR1R2, C═O, C═S, O, or S;
n is 1 or 2;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group; and wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted.
In one embodiment, L is represented by one of the following structures:
wherein each X1 and X2 independently represents NR1, CR1, SiR1, CR1R2, C═O, C═S, O, or S;
each X3 and X4 independently represents N, P, B, CR1, SiR1, CR1R2, C═O, C═S, O, or S;
Y represents N, P, CR1, or SiR1;
each Y1 and Y2 independently represents O, S, NR1, or CR1R2
W represents O, NR1, or S;
each occurrence of R1 and R2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, ether, ester, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;
wherein at least one substituent R1 and R2 comprises an electron accepting group; and
wherein any two adjacent R1 and R2 are optionally joined or fused together to form a ring which is optionally substituted.
In one embodiment, L is represented by one of the following structures:
wherein each X represents S, O, C(R)2, NR, or PR;
wherein each R is independently selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
In one embodiment, L is represented by one of the following structures:
wherein each X represents S, O, C(R)2, NR, or PR;
wherein each W represents an electron withdrawing group selected from the group consisting of halogen, CF3, CN, C(O)R, CO2R, NO2, and SO2R; and
wherein each R is independently selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
In one embodiment, L is represented by one of the following structures:
wherein each R is independently selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
In one embodiment, each R represents an aryl substituent which is optionally substituted. In one embodiment, each R represents an aryl substituent which is substituted at the 2- or 6-position or which is substituted at the 2- and the 6-positions relative to the bond to the carbene nitrogen. In one embodiment, each R represents a 2-6-disubstituted aryl, wherein each substituent is an alkyl group. In one embodiment, the alkyl group substituent on R is methyl or isopropyl. In one embodiment, each R represents a 2,6-diisopropylphenyl group.
In one embodiment, Z is selected from the group consisting of an alkyl anion, aryl anion, heteroaryl anion, halide, trifluoromethylsulfonate, amide, alkoxide, sulfide, and phosphide, wherein Z may be further substituted.
In one embodiment, Z is represented by one of the following structures:
wherein the dashed line indicates the bond to M1; and
each occurrence Y is selected from the group consisting of N and CR; and
each R independently represents a substituent selected from the group consisting of hydrogen, deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitro, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; wherein any two adjacent substituents may together join to form a ring.
In one embodiment, Z is represented by one of the following structures:
wherein the dashed line indicates the bond to M1.
In one embodiment, the compound is represented by one of the following structures:
wherein dipp represents 2,6-diisopropylphenyl.
In another aspect, the present disclosure provides a formulation comprising a compound of the present disclosure.
In another aspect, the present disclosure relates to an organic light emitting device (OLED) comprising an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound of the present disclosure.
A consumer product comprising an organic light-emitting device (OLED) is also described. The OLED includes an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer includes a compound of the present disclosure.
In some embodiments, the OLED has one or more characteristics selected from the group consisting of being flexible, being rollable, being foldable, being stretchable, and being curved. In some embodiments, the OLED is transparent or semi-transparent. In some embodiments, the OLED further comprises a layer comprising carbon nanotubes.
In some embodiments, the OLED further comprises a layer comprising a delayed fluorescent emitter. In some embodiments, the OLED comprises a RGB pixel arrangement or white plus color filter pixel arrangement. In some embodiments, the OLED is a mobile device, a hand held device, or a wearable device. In some embodiments, the OLED is a display panel having less than 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a display panel having at least 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a lighting panel.
In some embodiments, the compound can be an emissive dopant. In some embodiments, the compound can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence; see, e.g., U.S. application Ser. No. 15/700,352, which is hereby incorporated by reference in its entirety), triplet-triplet annihilation, or combinations of these processes. In some embodiments, the emissive dopant can be a racemic mixture, or can be enriched in one enantiomer. In some embodiments, the compound is neutrally charged. In some embodiments, the compound can be homoleptic (each ligand is the same). In some embodiments, the compound can be heteroleptic (at least one ligand is different from others). When there are more than one ligand coordinated to a metal, the ligands can all be the same in some embodiments. In some other embodiments, at least one ligand is different from the other ligands. In some embodiments, every ligand can be different from each other. This is also true in embodiments where a ligand being coordinated to a metal can be linked with other ligands being coordinated to that metal to form a tridentate, tetradentate, pentadentate, or hexadentate ligands. Thus, where the coordinating ligands are being linked together, all of the ligands can be the same in some embodiments, and at least one of the ligands being linked can be different from the other ligand(s) in some other embodiments.
In some embodiments, the compound can be used as a phosphorescent sensitizer in an OLED where one or multiple layers in the OLED contains an acceptor in the form of one or more fluorescent and/or delayed fluorescence emitters. In some embodiments, the compound can be used as one component of an exciplex to be used as a sensitizer. As a phosphorescent sensitizer, the compound must be capable of energy transfer to the acceptor and the acceptor will emit the energy or further transfer energy to a final emitter. The acceptor concentrations can range from 0.001% to 100%. The acceptor could be in either the same layer as the phosphorescent sensitizer or in one or more different layers. In some embodiments, the acceptor is a TADF emitter. In some embodiments, the acceptor is a fluorescent emitter. In some embodiments, the emission can arise from any or all of the sensitizer, acceptor, and final emitter.
According to another aspect, a formulation comprising the compound described herein is also disclosed.
The OLED disclosed herein can be incorporated into one or more of a consumer product, an electronic component module, and a lighting panel. The organic layer can be an emissive layer and the compound can be an emissive dopant in some embodiments, while the compound can be a non-emissive dopant in other embodiments.
The organic layer can also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the hosts used maybe a) bipolar, b) electron transporting, c) hole transporting or d) wide band gap materials that play little role in charge transport. In some embodiments, the host can include a metal complex. The host can be a triphenylene containing benzo-fused thiophene or benzo-fused furan. Any substituent in the host can be an unfused substituent independently selected from the group consisting of CnH2n+1, OCnH2n+1, OAr1, N(CnH2n+1)2, N(Ar1)(Ar2), CH═CH—CnH2n+1, Ar1, Ar1—Ar2, and CnH2n—Ar1, or the host has no substitutions. In the preceding substituents n can range from 1 to 10; and Ar1 and Ar2 can be independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof. The host can be an inorganic compound. For example a Zn containing inorganic material e.g. ZnS.
The host can be a compound comprising at least one chemical group selected from the group consisting of triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene. The host can include a metal complex. The host can be, but is not limited to, a specific compound selected from the group consisting of:
and combinations thereof.
Additional information on possible hosts is provided below.
In yet another aspect of the present disclosure, a formulation that comprises the novel compound disclosed herein is described. The formulation can include one or more components selected from the group consisting of a solvent, a host, a hole injection material, hole transport material, electron blocking material, hole blocking material, and an electron transport material, disclosed herein.
The present disclosure encompasses any chemical structure comprising the novel compound of the present disclosure, or a monovalent or polyvalent variant thereof. In other words, the inventive compound, or a monovalent or polyvalent variant thereof, can be a part of a larger chemical structure. Such chemical structure can be selected from the group consisting of a monomer, a polymer, a macromolecule, and a supramolecule (also known as supermolecule). As used herein, a “monovalent variant of a compound” refers to a moiety that is identical to the compound except that one hydrogen has been removed and replaced with a bond to the rest of the chemical structure. As used herein, a “polyvalent variant of a compound” refers to a moiety that is identical to the compound except that more than one hydrogen has been removed and replaced with a bond or bonds to the rest of the chemical structure. In the instance of a supramolecule, the inventive compound can also be incorporated into the supramolecule complex without covalent bonds.
Combination with Other Materials
The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination. Conductivity Dopants:
A charge transport layer can be doped with conductivity dopants to substantially alter its density of charge carriers, which will in turn alter its conductivity. The conductivity is increased by generating charge carriers in the matrix material, and depending on the type of dopant, a change in the Fermi level of the semiconductor may also be achieved. Hole-transporting layer can be doped by p-type conductivity dopants and n-type conductivity dopants are used in the electron-transporting layer.
Non-limiting examples of the conductivity dopants that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP01617493, EP01968131, EP2020694, EP2684932, US20050139810, US20070160905, US20090167167, US2010288362, WO06081780, WO2009003455, WO2009008277, WO2009011327, WO2014009310, US2007252140, US2015060804, US20150123047, and US2012146012.
A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but are not limited to: a phthalocyanine or porphyrin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and silane derivatives; a metal oxide derivative, such as MoOx; a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.
Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:
Each of Ar1 to Ar9 is selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each Ar may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In one aspect, Ar1 to Ar9 is independently selected from the group consisting of:
wherein k is an integer from 1 to 20; X101 to X108 is C (including CH) or N; Z101 is NAr1, O, or S; has the same group defined above.
Examples of metal complexes used in HIL or HTL include, but are not limited to the following general formula:
wherein Met is a metal, which can have an atomic weight greater than 40; (Y101-Y102) is a bidentate ligand, Y101 and Y102 are independently selected from C, N, O, P, and S; L101 is an ancillary ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.
In one aspect, (Y101-Y102) is a 2-phenylpyridine derivative. In another aspect, (Y101-Y102) is a carbene ligand. In another aspect, Met is selected from Ir, Pt, Os, and Zn. In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc+/Fc couple less than about 0.6 V.
Non-limiting examples of the HIL and HTL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN102702075, DE102012005215, EP01624500, EP01698613, EP01806334, EP01930964, EP01972613, EP01997799, EP02011790, EP02055700, EP02055701, EP1725079, EP2085382, EP2660300, EP650955, JP07-073529, JP2005112765, JP2007091719, JP2008021687, JP2014-009196, KR20110088898, KR20130077473, TW201139402, U.S. Ser. No. 06/517,957, US20020158242, US20030162053, US20050123751, US20060182993, US20060240279, US20070145888, US20070181874, US20070278938, US20080014464, US20080091025, US20080106190, US20080124572, US20080145707, US20080220265, US20080233434, US20080303417, US2008107919, US20090115320, US20090167161, US2009066235, US2011007385, US20110163302, US2011240968, US2011278551, US2012205642, US2013241401, US20140117329, US2014183517, U.S. Pat. Nos. 5,061,569, 5,639,914, WO05075451, WO07125714, WO08023550, WO08023759, WO2009145016, WO2010061824, WO2011075644, WO2012177006, WO2013018530, WO2013039073, WO2013087142, WO2013118812, WO2013120577, WO2013157367, WO2013175747, WO2014002873, WO2014015935, WO2014015937, WO2014030872, WO2014030921, WO2014034791, WO2014104514, WO2014157018.
EBL:
An electron blocking layer (EBL) may be used to reduce the number of electrons and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies, and/or longer lifetime, as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the EBL interface. In one aspect, the compound used in EBL contains the same molecule or the same functional groups used as one of the hosts described below.
The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. Any host material may be used with any dopant so long as the triplet criteria is satisfied.
Examples of metal complexes used as host are preferred to have the following general formula:
wherein Met is a metal; (Y103-Y104) is a bidentate ligand, Y103 and Y104 are independently selected from C, N, O, P, and S; L101 is an another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.
In one aspect, the metal complexes are:
wherein (O—N) is a bidentate ligand, having metal coordinated to atoms O and N.
In another aspect, Met is selected from Ir and Pt. In a further aspect, (Y103-Y104) is a carbene ligand.
In one aspect, the host compound contains at least one of the following groups selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each option within each group may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In one aspect, the host compound contains at least one of the following groups in the molecule:
wherein R101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. k is an integer from 0 to 20 or 1 to 20. X101 to X108 are independently selected from C (including CH) or N. Z101 and Z102 are independently selected from NR101, O, or S.
Non-limiting examples of the host materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP2034538, EP2034538A, EP2757608, JP2007254297, KR20100079458, KR20120088644, KR20120129733, KR20130115564, TW201329200, US20030175553, US20050238919, US20060280965, US20090017330, US20090030202, US20090167162, US20090302743, US20090309488, US20100012931, US20100084966, US20100187984, US2010187984, US2012075273, US2012126221, US2013009543, US2013105787, US2013175519, US2014001446, US20140183503, US20140225088, US2014034914, U.S. Pat. No. 7,154,114, WO2001039234, WO2004093207, WO2005014551, WO2005089025, WO2006072002, WO2006114966, WO2007063754, WO2008056746, WO2009003898, WO2009021126, WO2009063833, WO2009066778, WO2009066779, WO2009086028, WO2010056066, WO2010107244, WO2011081423, WO2011081431, WO2011086863, WO2012128298, WO2012133644, WO2012133649, WO2013024872, WO2013035275, WO2013081315, WO2013191404, WO2014142472, US20170263869, US20160163995, U.S. Pat. No. 9,466,803,
One or more additional emitter dopants may be used in conjunction with the compound of the present disclosure. Examples of the additional emitter dopants are not particularly limited, and any compounds may be used as long as the compounds are typically used as emitter materials. Examples of suitable emitter materials include, but are not limited to, compounds which can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence), triplet-triplet annihilation, or combinations of these processes.
Non-limiting examples of the emitter materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103694277, CN1696137, EB01238981, EP01239526, EP01961743, EP1239526, EP1244155, EP1642951, EP1647554, EP1841834, EP1841834B, EP2062907, EP2730583, JP2012074444, JP2013110263, JP4478555, KR1020090133652, KR20120032054, KR20130043460, TW201332980, U.S. Ser. No. 06/699,599, U.S. Ser. No. 06/916,554, US20010019782, US20020034656, US20030068526, US20030072964, US20030138657, US20050123788, US20050244673, US2005123791, US2005260449, US20060008670, US20060065890, US20060127696, US20060134459, US20060134462, US20060202194, US20060251923, US20070034863, US20070087321, US20070103060, US20070111026, US20070190359, US20070231600, US2007034863, US2007104979, US2007104980, US2007138437, US2007224450, US2007278936, US20080020237, US20080233410, US20080261076, US20080297033, US200805851, US2008161567, US2008210930, US20090039776, US20090108737, US20090115322, US20090179555, US2009085476, US2009104472, US20100090591, US20100148663, US20100244004, US20100295032, US2010102716, US2010105902, US2010244004, US2010270916, US20110057559, US20110108822, US20110204333, US2011215710, US2011227049, US2011285275, US2012292601, US20130146848, US2013033172, US2013165653, US2013181190, US2013334521, US20140246656, US2014103305, U.S. Pat. Nos. 6,303,238, 6,413,656, 6,653,654, 6,670,645, 6,687,266, 6,835,469, 6,921,915, 7,279,704, 7,332,232, 7,378,162, 7,534,505, 7,675,228, 7,728,137, 7,740,957, 7,759,489, 7,951,947, 8,067,099, 8,592,586, 8,871,361, WO06081973, WO06121811, WO07018067, WO07108362, WO07115970, WO07115981, WO08035571, WO2002015645, WO2003040257, WO2005019373, WO2006056418, WO2008054584, WO2008078800, WO2008096609, WO2008101842, WO2009000673, WO2009050281, WO2009100991, WO2010028151, WO2010054731, WO2010086089, WO2010118029, WO2011044988, WO2011051404, WO2011107491, WO2012020327, WO2012163471, WO2013094620, WO2013107487, WO2013174471, WO2014007565, WO2014008982, WO2014023377, WO2014024131, WO2014031977, WO2014038456, WO2014112450.
A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies and/or longer lifetime as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the HBL interface.
In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above.
In another aspect, compound used in HBL contains at least one of the following groups in the molecule:
wherein k is an integer from 1 to 20; L101 is another ligand, k′ is an integer from 1 to 3.
Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.
In one aspect, compound used in ETL contains at least one of the following groups in the molecule:
wherein R101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. Ar1 to Ar3 has the similar definition as Ar's mentioned above. k is an integer from 1 to 20. X101 to X108 is selected from C (including CH) or N.
In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:
wherein (O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L101 is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal.
Non-limiting examples of the ETL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103508940, EP01602648, EP01734038, EP01956007, JP2004-022334, JP2005149918, JP2005-268199, KR0117693, KR20130108183, US20040036077, US20070104977, US2007018155, US20090101870, US20090115316, US20090140637, US20090179554, US2009218940, US2010108990, US2011156017, US2011210320, US2012193612, US2012214993, US2014014925, US2014014927, US20140284580, U.S. Pat. Nos. 6,656,612, 8,415,031, WO2003060956, WO2007111263, WO2009148269, WO2010067894, WO2010072300, WO2011074770, WO2011105373, WO2013079217, WO2013145667, WO2013180376, WO2014104499, WO2014104535,
In tandem or stacked OLEDs, the CGL plays an essential role in the performance, which is composed of an n-doped layer and a p-doped layer for injection of electrons and holes, respectively. Electrons and holes are supplied from the CGL and electrodes. The consumed electrons and holes in the CGL are refilled by the electrons and holes injected from the cathode and anode, respectively; then, the bipolar currents reach a steady state gradually. Typical CGL materials include n and p conductivity dopants used in the transport layers.
In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. Thus, any specifically listed substituent, such as, without limitation, methyl, phenyl, pyridyl, etc. may be undeuterated, partially deuterated, and fully deuterated versions thereof. Similarly, classes of substituents such as, without limitation, alkyl, aryl, cycloalkyl, heteroaryl, etc. also may be undeuterated, partially deuterated, and fully deuterated versions thereof.
Thermally assisted delayed fluorescence (TADF), also known as E-type delayed fluorescence, has been investigated in a wide range of photophysical and photochemical applications (C. A. Parker and C. G. Hatchard, Trans. Faraday Society, 1961, 57, 1894-1904; R. Greinert, et al., Journal of Biochemical and Biophysical Methods, 1979, 1, 77-83; V. Jankus, et al., Adv. Mater., 2013, 25, 1455-1459; I. Lukomsky, et al., Journal of Fluorescence, 1994, 4, 49-51; N. A. Borisevich, et al., Journal of Fluorescence, 2006, 16, 649-653; Y. Zhang, et al., Appl. Phys. Lett., 2008, 92, 013905; B. Frederichs and H. Staerk, Chem. Phys. Lett., 2008, 460, 116-118; J. C. Deaton, et al., Journal of the American Chemical Society, 2010, 132, 9499-9508; G. V. Zakharova, et al., High Energ. Chem., 2014, 48, 76-80; I S Vinklárek, et al., Photochemical & Photobiological Sciences, 2017, 16, 507-518; B. Vigante, et al., Chemistry—A European Journal, 2019, 25, 3325-3336). The process involves the endothermic intersystem crossing (ISC) from the triplet excited state (T1) to singlet (S1) excited state followed by emission from the S1 state (
Three- and four-coordinate Cu(I) complexes have also been reported that demonstrate TADF behavior, from largely metal to ligand charge transfer (MLCT) transitions (H. Yersin, et al., Coord. Chem. Rev., 2011, 255, 2622-2652; R. Czerwieniec, et al., Inorganic Chemistry, 2011, 50, 8293-8301; M. J. Leitl, et al., Journal of the American Chemical Society, 2014, 136, 16032-16038; T. Hofbeck, et al., Journal of the American Chemical Society, 2015, 137, 399-404; R. Czerwieniec, et al., Coord. Chem. Rev., 2016, 325, 2-28; H. Yersin, et al., Chemphyschem, 2017, 18, 3508-3535). Recently, a significant advance in Cu(I)-based TADF materials was achieved using two-coordinate complexes with a carbene ligand to serve as an acceptor and an amide ligand as a donor (D. Di, et al., Science, 2017, 356, 159; A. S. Romanov, et al., Chemistry—A European Journal, 2017, 23, 4625-4637; P. J. Conaghan, et al., Adv. Mater., 2018, 30, 1802285; A. S. Romanov, et al., Chem. Mater., 2019, 31, 3613-3623; R. Hamze, et al., Science, 2019, 363, 601; S. Shi, et al., Journal of the American Chemical Society, 2019, 141, 3576-3588; R. Hamze, et al., Journal of the American Chemical Society, 2019, 141, 8616-8626; A. S. Romanov, et al., Chemical Science, 2020, 11, 435-446; P. J. Conaghan, et al., Nature Communications, 2020, 11, 1758; M. Gernert, et al., Journal of the American Chemical Society, 2020, 142, 8897-8909; A. Ying, et al., ACS Applied Materials & Interfaces, 2021, 13, 13478-13486; F. Chotard, et al., Chem. Mater., 2020, 32, 6114-6122). In addition to the copper complexes, isoelectronic silver and gold based complexes have been shown to give highly efficient TADF (A. S. Romanov, et al., Advanced Optical Materials, 2018, 6, 1801347; T.-y. Li, et al., Journal of the American Chemical Society, 2020, 142, 6158-6172). Here the (carbene)M(amide) family of complexes will be referred to as cMa for M=Cu(I), Ag(I) and Au(I). Early reports of complexes with cMa structures and their promising luminescent properties (H. M. J. Wang, et al., Organometallics, 2005, 24, 486-493) led to further study (V. W.-W. Yam, et al., Journal of the American Chemical Society, 2009, 131, 912-913; M. C. Gimeno, et al., Organometallics, 2012, 31, 7146-7157; A. Gomez-Suarez, et al., Beilstein J. Org. Chem., 2013, 9, 2216-2223) and successful application in OLEDs generated new enthusiasm for these types of emitters. Investigations have been carried out focusing on two-coordinate TADF complexes experimentally and theoretically, to develop structure-property relationships and design strategies to achieve high radiative (kr) and low non-radiative (km) decay rates (J. Feng, et al., Adv. Funct. Mater., 2020, 30, 1908715; C. R. Hall, et al., The Journal of Physical Chemistry Letters, 2018, 9, 5873-5876; J. Feng, et al., Adv. Funct. Mater., 2021, 31, 2005438; S. Thompson, et al., J. Chem. Phys., 2018, 149, 014304; E. J. Taffet, et al., The Journal of Physical Chemistry Letters, 2018, 9, 1620-1626; T.-y. Li, et al., Chemistry—A European Journal, 2021, 27, 6191-6197).
TADF molecules fall into two basic categories, depending on whether they have slow or fast rates for intersystem crossing (ISC). Organic TADF materials generally have slow ISC rates (kISC=105˜108 s−1) owing to weak spin-orbital coupling (SOC), which makes fluorescent radiative decay (krS
k
r
TADF
=k
r
S
·K
eq(T1⇄S1) (eq 1)
In this equation, krTADF is dependent on krS
According to the analysis above, predictions can be made regarding the TADF properties of cMa complexes without prior knowledge about ISC rates since only krS
The general synthetic route to the compounds studied here is presented in Scheme 1, detailed synthetic procedures and characterization are included below. The N-heterocyclic carbene (NHC) precursor triflate salts 2 were prepared according to a published Ag(I) catalyzed 6-endo-dig cyclization (C. Zhang, et al., New J. Chem., 2017, 41, 1889-1892). The diisopropyl phenyl (dipp) substituents on the carbene nitrogen atoms hinder axial rotation around the metal-ligand bonds (R. Hamze, et al., Science, 2019, 363, 601; T.-y. Li, et al., Journal of the American Chemical Society, 2020, 142, 6158-6172). The preparation of the intermediate complex 3 varied depending on the metal ions. For Cu complexes, deprotonation of 2 with strong base provided the free carbene in-situ, and the products were obtained by reacting it with CuCl. For Ag complexes, 2 was treated with Ag2O and the triflate salt was isolated. The Au chloride complexes were synthesized via a metal exchange reaction with the Ag triflate salts using chloro(dimethylsulfide) gold. The cMa complexes were then prepared by reacting 3 with deprotonated carbazole or 3-cyanocarbazole, in yields over 70%. All these complexes were obtained as light yellow to orange crystalline powders. No obvious decomposition is observed in the 1H NMR spectra when the complexes are stored under ambient conditions.
Acronyms to distinguish the complexes are given as R1-M or R1-MCN, where R1 is Me (methyl) or Ph (phenyl) according to the substituent group, M is Cu, Ag or Au and the superscript CN is shown when R2 is CN.
Scheme 1: General synthetic route for the coinage metal complexes, note, the counter ion for 3 is triflate in Ag complex.
Molecular structures for five of the complexes were determined using single crystal X-ray analysis. Critical crystallographic data was presented and molecular structures of MeCu and Ph-AuCN were shown in
The electrochemical properties of the complexes were investigated using cyclic voltammetry (CV) and differential pulsed voltammetry (DPV) methods (see below for the electrochemical traces and data). All the complexes undergo irreversible oxidation in DMF solution. For complexes with same ligands, the metal ion influenced Eox in a sequence of Ag<Cu<Au in steps of 0.1 V. Upon introduction of CN on the Cz ligand, the oxidation potential (Eox) positively shifted by 0.24-0.29 V. A single reversible reduction (Ered=−2.25 to −2.37 V) is observed for complexes with methyl substituted carbenes within the measurable solvent window. Complexes with phenyl substituted carbenes show two reversible reductions, a reversible reduction near −2.0 V and an irreversible reduction at roughly −2.6 V. It is noteworthy that variations in Ered between complexes with the same ligands and different metal ions are relatively small, i.e., the range for Cu, Ag and Au complexes is 0.07 V.
The photophysical properties of the two-coordinate complexes were studied in fluid solution and in doped polystyrene (PS) films. Other than a difference in extinction coefficients between the three metals (vide infra) the absorption and emission spectra for Cu, Ag and Au complexes with identical ligands show very similar profiles. Representative spectra for the Cu derivatives are shown in
aAbsorption data recorded in toluene solution, luminescence data in doped PS (1 wt %) films. Ftje c
The cMa complexes all display a broad visible ICT emission band when doped in a PS film at room temperature (
As discussed above, the rate of emission is controlled by krS
In previous studies of related cMa complexes values for krS
The radiative decay rate for TADF (krTADF) for systems with fast ISC is determined principally by krS
where ekφ and hkφ are the electron and hole orbital pairs and σk is the amplitude of a given orbital pair that contributes to the total NTO. The overlap value was numerically evaluated as described previously (S. P. McGlynn, et al., Adv. Funct. Mater., 2021, 31, 2101175). Table 3 gives the NTO overlap values for the S1 and T1 (ICT) states, 1ICT and 3ICT, respectively. As observed previously (T. Chen, et al., Sci. Rep., 2015, 5, 10923), the NTO overlap is larger for the triplet state than the singlet state, however the trends are the same as a function of metal, i.e. 3ICT NTO overlaps fall in the order Au>Cu>Ag. These twelve complexes present ideal candidates to examine the dependence of krS
Experimental values for ΔEST and kr,SBS
According to the Einstein radiation law, the radiative decay rate is proportional to the cube of the emission energy. The reduced krTADF (krTADF/E3, where E is the emission energy derived from the emission maximum) for complexes in this work, as well as other monometallic and bimetallic (carbene)M(N-carbazolyl) complexes previously reported, was plotted as a function of the NTO overlap values calculated for 1ICT state (
A similar analysis of NTO overlap was carried out for selected organic TADF molecules to evaluate the scope of the correlations. Organic TADF molecules were chosen as listed in Table S12 and their photophysical properties were collected from literature (H. Tanaka, et al., Chem. Commun, 2012, 48, 11392-11394; Y. Liu, et al., Nature Reviews Materials, 2018, 3, 18020; M. Godumala, et al., Journal of Materials Chemistry C, 2019, 7, 2172-2198; H. Noda, et al., Nature Materials, 2019, 18, 1084-1090; H. Noda, et al., Science Advances, 2018, 4, 6910; L.-S. Cui, et al., Nature Photonics, 2020, 14, 636-642; Y. Kondo, et al., Nature Photonics, 2019, 13, 678-682; J. U. Kim, et al., Nature Communications, 2020, 11, 1765; N. Aizawa, et al., Nature Communications, 2020, 11, 3909; D. Hall, et al., Advanced Optical Materials, 2020, 8, 1901627; J. Lee, et al., Chem. Mater., 2017, 29, 8012-8020; S. Jeong, et al., Journal of Materials Chemistry C, 2018, 6, 9049-9054; I. S. Park, et al., Adv. Funct. Mater., 2018, 28, 1802031; S. Wang, et al., Angew. Chem. Int. Ed., 2015, 54, 13068-13072; K. Shizu, et al., The Journal of Physical Chemistry C, 2015, 119, 26283-26289; S. Hirata, et al., Nature Materials, 2015, 14, 330-336; T. Hatakeyama, et al., Adv. Mater., 2016, 28, 2777-2781; T.-A. Lin, et al., Adv. Mater., 2016, 28, 6976-6983; Q. Zhang, et al., Adv. Mater., 2015, 27, 2096-2100; J. Guo, et al., Adv. Funct. Mater., 2017, 27, 1606458; G. Xie, et al., Adv. Mater., 2016, 28, 181-187). Although the theoretical methods used to determine values for the NTO overlap were the same as those applied for the coinage metal complexes, different methods used to obtain experimental values for organic TADF molecules make the comparisons problematic. Nevertheless, the theoretical ΔEST values can still be evaluated as all compounds were calculated using the same method and basis set and show a clear increase with greater NTO overlap (
In summary, a series of twelve two-coordinate Cu, Ag and Au complexes were synthesized with cMa structure. They all display TADF emission from ICT states with fast decay lifetimes and high luminescence efficiency. NTO overlaps of the emissive 1ICT states were quantified using theoretical calculations. The use of different metal ions and chemical modification on both ligands leads to NTO overlap values that cover a wide range (from 0.21 to 0.41). Detailed theoretical and experimental investigations shed light on the influence of NTO overlap on ΔEST and krS
Materials and Methods
General information: All reactions were carried out using Schleck line system under N2 in oven dried glassware. Organic and inorganic materials were used as commercial grade without further purifications. Anhydrous solvents were purified by Class Contour solvent system by SG Water USA, LLC. 1H and 13C NMR spectra were recorded on a Varian Mercury 400 instrument. Elemental analyses were performed at University of Southern California, using a Fisher CHNS 2000 instrument.
Syntheses and Characterization
General procedure for the carbene precursors: The methyl or phenyl substituted acetylenyl formamidine 1 was synthesized according to previous method, and the following 6-endo-dig cyclization was performed using a modified procedure (C. Zhang, et al., New J. Chem., 2017, 41, 1889-1892; J. Wang, et al., Nat. Commun., 2017, 8, 14625). Equal equivalent of 1 (500 mg) and AgOTf (300 mg) were dissolved in 20 mL dichloromethane (DCE) in a sealed glass vial. The solution was refluxed for 1 h and the clear colorless solution turned into dark brown suspension with Ag mirror on the wall. After cooling down to room temperature, the suspension was filtrated through Celite. The filtration was injected to another sealed vial and 1 equiv. of HOTf was added dropwise. The system was stirred at room temperature for another 1 h. The solution was filtered through Celite. After removing all the volatiles, the raw product was washed by cold ether for three times, giving the carbene precursors as white powder.
Obtained 300 mg, yield 91%. 1H NMR (400 MHz, acetone) δ 10.35 (s, 1H), 7.80-7.74 (m, 1H), 7.69-7.60 (m, 3H), 7.52 (d, J=7.8 Hz, 2H), 7.36 (s, 1H), 2.99 (sept, J=6.7 Hz, 2H), 2.89 (sept, J=6.8 Hz, 2H), 2.33 (d, J=1.1 Hz, 3H), 1.38 (d, J=6.7 Hz, 6H), 1.28 (d, J=6.8 Hz, 12H), 1.19 (d, J=6.7 Hz, 6H).
Obtained 298 mg, yield 93%. 1H NMR (400 MHz, acetone) δ 10.41 (d, J=0.5 Hz, 1H), 7.70-7.64 (m, 1H), 7.62-7.55 (m, 1H), 7.55-7.50 (m, 3H), 7.47 (t, J=1.4 Hz, 1H), 7.46-7.38 (m, 6H), 3.20 (sept, J=6.7 Hz, 2H), 2.98 (sept, J=6.7 Hz, 2H), 1.30 (d, J=6.8 Hz, 6H), 1.24 (d, J=6.8 Hz, 6H), 1.19 (d, J=6.7 Hz, 6H), 1.16 (d, J=6.6 Hz, 6H).
Synthesis of the Cu complexes: Carbene precursor was dissolved in 150 mL anhydrous THF at room temperature and 1.05 equiv. of KHMDS (0.5M in toluene) was injected dropwise. After stirring at room temperature for 3 h, 1.1 equiv. of CuCl was added in one portion and the system was kept stirring for overnight. Then, the mixture was filtered through Celite. After removing the volatiles, the residue was sonicated in ether giving the intermediate complex 3 as beige powder (yield around 60%), which was used in the following reactions without further purifications.
Me-Cu, Me-CuCN, Ph-Cu and Ph-CuCN were synthesized according to a known procedure which was well described in previous publications (R. Hamze, et al., Science, 2019, 363, 601; S. Shi, et al., Journal of the American Chemical Society, 2019, 141, 3576-3588; R. Hamze, et al., Journal of the American Chemical Society, 2019, 141, 8616-8626).
Me-Cu was obtained with a yield of 80% as yellow powder. 1H NMR (400 MHz, acetone) δ 7.93 (t, J=7.8 Hz, 1H), 7.81 (t, J=7.8 Hz, 1H), 7.74 (d, J=7.6 Hz, 2H), 7.69 (d, J=7.9 Hz, 2H), 7.58 (d, J=7.8 Hz, 2H), 6.85 (ddd, J=8.2, 7.0, 1.3 Hz, 2H), 6.79-6.69 (m, 3H), 5.60 (d, J=8.1 Hz, 2H), 2.99 (sept, J=6.7 Hz, 4H), 2.15 (d, J=0.9 Hz, 3H), 1.39 (d, J=6.8 Hz, 6H), 1.28 (d, J=6.8 Hz, 6H), 1.23 (dd, J=9.5, 6.9 Hz, 12H). 13C NMR (101 MHz, acetone) δ 158.51, 155.04, 149.80, 145.77, 145.62, 136.99, 135.97, 131.48, 130.39, 125.86, 124.91, 123.95, 122.78, 118.44, 115.09, 114.58, 111.72, 29.65, 28.75, 28.33, 24.72, 23.63, 23.37, 22.60, 20.18. Elemental analysis calculated C 74.57, H 7.02, N 6.36; found C 74.24, H, 7.05 N 6.13.
Me-CuCN was obtained with a yield of 77% as bright yellow powder. 1H NMR (400 MHz, acetone) δ 8.18-8.12 (m, 1H), 7.97 (t, J=7.8 Hz, 1H), 7.90-7.81 (m, 2H), 7.71 (d, J=7.9 Hz, 2H), 7.59 (d, J=7.8 Hz, 2H), 7.11 (dd, J=8.5, 1.7 Hz, 1H), 6.98 (ddd, J=8.2, 7.1, 1.3 Hz, 1H), 6.88 (td, J=7.5, 1.0 Hz, 1H), 6.74 (d, J=1.0 Hz, 1H), 5.65 (d, J=8.1 Hz, 1H), 5.55 (dd, J=8.5, 0.5 Hz, 1H), 3.06-2.91 (m, 4H), 2.15 (s, 3H), 1.38 (d, J=6.8 Hz, 6H), 1.24 (dd, J=10.7, 6.8 Hz, 12H), 1.19 (d, J=6.9 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.41, 155.07, 151.55, 150.44, 145.87, 145.70, 136.99, 135.98, 131.67, 130.59, 125.98, 125.66, 125.02, 124.52, 124.19, 123.75, 123.23, 121.35, 119.26, 117.12, 115.12, 115.05, 112.01, 96.85, 28.86, 24.76, 23.64, 23.37, 22.57, 20.17. Elemental analysis calculated C 73.60, H 6.62, N 8.17; found C 73.08, H 6.44, N 7.99.
Ph-Cu was obtained with a yield of 82% as yellow powder. 1H NMR (400 MHz, acetone) δ 7.82 (t, J=7.8 Hz, 1H), 7.77-7.70 (m, 3H), 7.60 (d, J=7.8 Hz, 2H), 7.47 (d, J=7.9 Hz, 3H), 7.37 (dd, J=5.1, 1.5 Hz, 4H), 6.82 (ddd, J=8.2, 7.0, 1.3 Hz, 2H), 6.78 (s, 1H), 6.71 (td, J=7.4, 1.0 Hz, 2H), 5.59-5.53 (m, 2H), 3.12 (dhept, J=20.3, 6.6 Hz, 4H), 1.29 (d, J=6.8 Hz, 6H), 1.26 (d, J=6.8 Hz, 6H), 1.23 (d, J=6.9 Hz, 6H), 1.17 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.40, 156.70, 149.77, 146.05, 145.93, 137.53, 136.00, 131.73, 131.34, 130.59, 130.50, 129.35, 128.21, 125.44, 125.03, 123.96, 122.75, 118.42, 115.06, 114.62, 113.14, 28.85, 25.51, 23.68, 23.63, 21.96. Elemental analysis calculated C 76.48, H 6.70, N 5.82; found C 76.23, H 6.44, N 5.64.
Ph-CuCN was obtained with a yield of 75% as bright yellow powder. 1H NMR (400 MHz, acetone) δ 8.16 (s, 1H), 7.89 (t, J=7.9 Hz, 2H), 7.81 (t, J=7.8 Hz, 1H), 7.64 (d, J=7.8 Hz, 2H), 7.51 (t, J=6.6 Hz, 2H), 7.49-7.44 (m, 1H), 7.40 (dd, J=8.7, 5.3 Hz, 4H), 7.11 (dd, J=8.5, 1.5 Hz, 1H), 6.98 (t, J=7.1 Hz, 1H), 6.89 (t, J=7.3 Hz, 1H), 6.83 (s, 1H), 5.65 (d, J=8.1 Hz, 1H), 5.54 (d, J=8.5 Hz, 1H), 3.15 (dtd, J=20.4, 13.5, 6.7 Hz, 4H), 1.29 (t, J=7.3 Hz, 12H), 1.24 (d, J=6.8 Hz, 6H), 1.19 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.31, 156.66, 151.51, 150.42, 146.12, 146.03, 137.58, 136.02, 131.61, 131.52, 130.70, 130.67, 129.34, 128.25, 125.63, 125.56, 125.15, 124.49, 124.20, 123.72, 123.24, 121.35, 119.24, 117.09, 115.16, 115.10, 113.41, 96.81, 28.84, 25.57, 23.69, 23.64, 21.93. Elemental analysis calculated C 75.52, H 6.34, N 7.50; found C 75.38, H 6.07, N 7.27.
Synthesis of the Ag complexes: Carbene precursor and 0.7 equiv. of Ag2O were stirred in 50 mL anhydrous CH2Cl2 at room temperature for 48 h with a coverage of aluminum foil. After removing the insoluble precipitates by filtration through Celite, the filtrate was dried to afford raw product. Then, the oily raw product was sonicated in ether to provide the final product as light purple powder (yield over 90%), which was used in the following reactions without further purifications.
Me-Ag, Me-AgCN, Ph-Ag and Ph-AgCN were synthesized according to a known procedure which was well described in previous publications.
Me-Ag was obtained with a yield of 79% as orange powder. 1H NMR (400 MHz, acetone) δ 7.88 (t, J=7.7 Hz, 1H), 7.77 (t, J=9.2 Hz, 3H), 7.68 (d, J=7.8 Hz, 2H), 7.56 (d, J=7.8 Hz, 2H), 6.93 (ddd, J=8.1, 7.0, 1.2 Hz, 2H), 6.80-6.70 (m, 3H), 6.04 (d, J=8.1 Hz, 2H), 2.98 (dq, J=13.4, 6.6 Hz, 4H), 2.23 (s, 3H), 1.39 (d, J=6.8 Hz, 6H), 1.34 (d, J=6.8 Hz, 6H), 1.28 (d, J=6.9 Hz, 6H), 1.24 (d, J=6.8 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.35, 158.30, 154.91, 154.84, 150.29, 145.41, 145.28, 138.25, 137.47, 131.43, 130.36, 125.81, 124.81, 123.84, 122.79, 118.59, 114.58, 114.44, 112.21, 28.84, 28.66, 24.71, 23.63, 23.50, 22.86, 20.49, 20.48. Elemental analysis calculated C 69.88, H 6.58, N 5.96; found C 69.43, H 6.52, N 5.86.
Me-AgCN was obtained with a yield of 75% as yellow powder. 1H NMR (400 MHz, acetone) δ 8.21 (s, 1H), 7.94 (t, J=7.9 Hz, 2H), 7.82 (t, J=7.8 Hz, 1H), 7.71 (d, J=7.8 Hz, 2H), 7.60 (d, J=7.8 Hz, 2H), 7.21 (dd, J=8.5, 1.6 Hz, 1H), 7.08 (t, J=7.6 Hz, 1H), 6.91 (t, J=7.3 Hz, 1H), 6.80 (s, 1H), 6.11 (d, J=8.1 Hz, 1H), 6.00 (d, J=8.4 Hz, 1H), 2.98 (m, 4H), 2.25 (d, J=0.8 Hz, 3H), 1.39 (d, J=6.8 Hz, 6H), 1.32 (d, J=6.8 Hz, 6H), 1.25 (dd, J=10.4, 6.8 Hz, 12H). 13C NMR (101 MHz, acetone) δ 158.29, 158.23, 154.94, 154.87, 145.53, 145.38, 138.28, 137.55, 131.58, 130.52, 125.92, 125.70, 124.92, 124.57, 123.92, 121.51, 119.39, 116.76, 115.04, 114.91, 112.40, 96.22, 28.83, 28.65, 24.75, 23.63, 23.52, 22.85, 20.48. Elemental analysis calculated C 69.13, H 6.22, N 7.68; found C 69.08, H 6.05, N 7.43.
Ph-Ag was obtained with a yield of 79% as yellow powder. 1H NMR (400 MHz, acetone) δ 7.85-7.70 (m, 4H), 7.60 (d, J=7.8 Hz, 2H), 7.53-7.46 (m, 3H), 7.45-7.38 (m, 4H), 6.92 (ddd, J=8.2, 7.0, 1.2 Hz, 2H), 6.87 (s, 1H), 6.78-6.69 (m, 2H), 6.02 (d, J=8.1 Hz, 2H), 3.26-2.99 (m, 4H), 1.35 (d, J=6.8 Hz, 6H), 1.29 (dd, J=12.4, 6.8 Hz, 12H), 1.15 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.21, 158.15, 156.44, 156.37, 150.29, 145.68, 145.56, 138.90, 137.54, 131.72, 131.32, 130.80, 130.48, 129.53, 128.31, 125.48, 124.93, 123.85, 122.76, 118.58, 114.55, 114.48, 113.61, 28.83, 28.81, 25.48, 23.88, 23.55, 22.24. Elemental analysis calculated C 72.06, H 6.31, N 5.48; found C 71.86, H 6.18, N 5.28.
Ph-AgCN was obtained with a yield of 73% as light yellow powder. 1H NMR (400 MHz, acetone) δ 8.20 (d, J=1.3 Hz, 1H), 7.92 (d, J=7.6 Hz, 1H), 7.86 (t, J=7.8 Hz, 1H), 7.79 (t, J=7.8 Hz, 1H), 7.63 (d, J=7.8 Hz, 2H), 7.52 (d, J=7.9 Hz, 2H), 7.50-7.47 (m, 1H), 7.46-7.38 (m, 4H), 7.20 (dd, J=8.5, 1.7 Hz, 1H), 7.07 (ddd, J=8.2, 7.0, 1.2 Hz, 1H), 6.94-6.86 (m, 2H), 6.09 (d, J=8.2 Hz, 1H), 6.02-5.95 (m, 1H), 3.21-3.04 (m, 4H), 1.34 (d, J=6.8 Hz, 6H), 1.28 (dd, J=8.4, 6.8 Hz, 12H), 1.15 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 158.14, 158.09, 156.35, 145.76, 145.68, 139.00, 137.62, 131.62, 131.46, 130.87, 130.63, 129.52, 128.35, 125.67, 125.59, 125.03, 124.54, 123.90, 121.52, 119.38, 116.73, 115.08, 114.95, 113.79, 96.19, 28.81, 28.78, 25.53, 23.89, 23.57, 22.22. Elemental analysis calculated C 71.30, H 5.98, N 7.08; found C 71.08, H 5.97, N 7.03.
Synthesis of the Au complexes: The Au(I)—Cl intermediate complexes were obtained by a metal ion exchange reaction. Equal equivalent of Carbene-AgOTf and (Me)2SAuCl were stirred in anhydrous CH2Cl2 for overnight. After the filtration through Celite, the filtrate was dried under vacuum. Excess amount of ether was added in the raw material and the intermediate complex was obtained as light purple precipitate (yield over 90%), which was used in the following reactions without further purifications.
Me-Au, Me-AuCN, Ph-Au and Ph-AuCN were synthesized according to a known procedure which was well described in previous publications.
Me-Au was obtained with a yield of 80% as orange powder. 1H NMR (400 MHz, acetone) δ 7.90 (t, J=7.8 Hz, 1H), 7.82-7.75 (m, 3H), 7.67 (d, J=7.8 Hz, 2H), 7.56 (d, J=7.8 Hz, 2H), 6.95 (ddd, J=8.2, 7.0, 1.3 Hz, 2H), 6.82-6.75 (m, 3H), 6.08 (dt, J=8.2, 0.9 Hz, 2H), 3.02-2.88 (m, 4H), 2.22 (d, J=1.0 Hz, 3H), 1.39 (dd, J=6.8, 5.7 Hz, 12H), 1.30 (d, J=6.9 Hz, 6H), 1.23 (d, J=6.8 Hz, 6H). 13C NMR (101 MHz, acetone) δ 201.36, 158.40, 155.16, 149.16, 145.44, 145.33, 137.11, 136.05, 131.11, 130.01, 125.41, 124.37, 123.59, 122.82, 118.41, 115.63, 113.79, 111.05, 28.74, 28.57, 24.09, 23.39, 23.05, 22.81, 20.30. Elemental analysis calculated C 62.04, H 5.84, N 5.29; found C 61.97, H 5.68, N 5.18.
Me-AuCN was obtained with a yield of 78% as yellow powder. 1H NMR (400 MHz, acetone) δ 8.22 (dd, J=1.7, 0.6 Hz, 1H), 7.93 (dd, J=11.1, 4.5 Hz, 2H), 7.82 (t, J=7.8 Hz, 1H), 7.69 (d, J=7.8 Hz, 2H), 7.60-7.54 (m, 2H), 7.22 (dd, J=8.5, 1.7 Hz, 1H), 7.08 (ddd, J=8.2, 7.1, 1.2 Hz, 1H), 6.93 (ddd, J=7.9, 7.1, 1.0 Hz, 1H), 6.80 (d, J=1.0 Hz, 1H), 6.13 (dt, J=8.2, 0.8 Hz, 1H), 6.05 (dd, J=8.5, 0.6 Hz, 1H), 3.01-2.86 (m, 4H), 2.22 (d, J=1.0 Hz, 3H), 1.37 (dd, J=6.8, 1.4 Hz, 12H), 1.28 (d, J=6.8 Hz, 6H), 1.22 (d, J=6.8 Hz, 6H). 13C NMR (101 MHz, acetone) δ 200.52, 158.44, 155.37, 151.13, 150.04, 145.74, 145.61, 137.31, 136.24, 131.50, 130.41, 125.89, 125.72, 124.71, 124.67, 124.02, 123.96, 123.07, 121.07, 119.42, 117.72, 114.54, 114.51, 111.60, 97.71, 24.30, 23.59, 23.25, 23.01, 20.49. Elemental analysis calculated C 61.61, H 5.54, N 6.84; found C 61.88, H 5.53, N 6.75.
Ph-Au was obtained with a yield of 82% as orange powder. 1H NMR (400 MHz, acetone) δ 7.85-7.71 (m, 4H), 7.58 (d, J=7.8 Hz, 2H), 7.50-7.42 (m, 3H), 7.38 (d, J=4.4 Hz, 4H), 6.93 (ddd, J=8.2, 7.0, 1.3 Hz, 2H), 6.86 (s, 1H), 6.77 (ddd, J=7.9, 7.1, 1.0 Hz, 2H), 6.05 (dt, J=8.2, 0.8 Hz, 2H), 3.07 (sept, J=6.7 Hz, 4H), 1.41 (d, J=6.8 Hz, 6H), 1.32 (d, J=6.8 Hz, 6H), 1.26 (d, J=6.8 Hz, 6H), 1.11 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 202.37, 158.56, 156.94, 149.36, 146.07, 145.78, 137.84, 136.36, 131.70, 131.26, 130.80, 130.32, 129.73, 128.27, 125.30, 124.70, 123.81, 123.02, 118.62, 115.84, 114.05, 112.78, 25.02, 23.81, 23.37, 22.47. Elemental analysis calculated C 64.55, H 5.65, N 4.91; found C 64.40, H 5.64, N 4.90.
Ph-AuCN was obtained with a yield of 80% as yellow powder. 1H NMR (400 MHz, acetone) δ 8.23 (dd, J=1.7, 0.6 Hz, 1H), 7.97-7.92 (m, 1H), 7.84 (dt, J=20.4, 7.8 Hz, 2H), 7.62 (d, J=7.8 Hz, 2H), 7.54-7.45 (m, 3H), 7.41 (d, J=4.3 Hz, 4H), 7.22 (dd, J=8.5, 1.7 Hz, 1H), 7.08 (ddd, J=8.3, 7.1, 1.3 Hz, 1H), 6.94 (ddd, J=8.0, 7.1, 1.0 Hz, 1H), 6.91 (s, 1H), 6.13 (dd, J=8.2, 0.8 Hz, 1H), 6.05 (dd, J=8.5, 0.6 Hz, 1H), 3.18-3.00 (m, 4H), 1.42 (d, J=6.8 Hz, 6H), 1.32 (d, J=6.8 Hz, 6H), 1.27 (d, J=6.8 Hz, 6H), 1.13 (d, J=6.7 Hz, 6H). 13C NMR (101 MHz, acetone) δ 201.38, 158.39, 156.87, 151.12, 150.03, 146.13, 145.87, 137.87, 136.35, 131.57, 131.42, 130.86, 130.50, 129.72, 128.28, 125.87, 125.40, 124.78, 124.69, 124.03, 123.95, 123.08, 121.07, 119.41, 117.70, 114.58, 114.57, 113.10, 97.69, 25.03, 23.79, 23.34, 22.44. Elemental analysis calculated C 64.09, H 5.38, N 6.36; found C 63.79, H 5.44, N 6.33.
Crystallography: All single crystal samples suitable for X-ray diffraction measurements were grown by slow diffusion of ether into CH2Cl2 solution. The diffraction intensity frames were collected on a Bruker APEX DUO 3-circle platform diffractometer using Cu Kα radiation (λ=1.54184 Å). The diffractometer was equipped with an APEX II CCD detector and an Oxford Cryosystems Cryostream 700 apparatus for low-temperature data collection adjusted to 100(2) K. The crystal was mounted in a Cryo-Loop using Paratone oil. The frames were integrated using the SAINT algorithm to give the hkl files. Data were corrected for absorption effects using the multiscan method (SADABS). The structures were solved by intrinsic phasing and refined with the Bruker SHELXTL software package. Crystal structures are provided in
Electrochemistry: Cyclic voltammetry (CV) and differential pulsed voltammetry (DPV) were performed using a VersaSTAT 3 potentiostat in anhydrous DMF under N2 atmosphere. A standard three-electrode system with a glassy carbon rod working electrode, a platinum wire counter electrode and a silver wire reference electrode was employed. Tetra-n-butyl ammonium hexafluorophosphate (TBAHF) was used as supporting electrolyte on a concentration of 0.1M. Ferrocene was used as internal reference and the redox potentials of the complexes were adjusting the ferrocene redox potentials as 0V. The Electrochmical data of the coinage metal complexes is provided in Table 4. CV and DPV curves for (carbene)Cu(carbazolyl) in DMF are shown in
aPotential values were obtained from DPV measurement using ferrocene/ferrocenium as internal reference whose potentials were adjusted as 0 V; bThe first reduction potential was used to calculated the gap when two reductions were observed; cKnown data from reference48
Molecular modeling: All theoretical calculations were carried out using Q-Chem 5.1 program as in gas phase and visualized using IQmol software. The ground state molecular geometries were optimized at the B3LYP/LACVP* level, followed by the TD-DFT calculations based on the optimized structures at the CAM-B3LYP/LACVP* level, aiming for the insight of vertical transitions. Details of NTOs were obtained by another TD-DFT calculations at the same level, and the NTO overlap values were calculated using the NTOverlap software written by Dr. Daniel Sylvinson (A. C. Tadle, et al., Adv. Funct. Mater., 2021, 31, 2101175). All the plots are provided with hydrogen atoms omitted for clarity. Calculated frontier molecule orbitals are shown in
Photophysics: Absorption spectra were recorded in dilute CH2Cl2 and toluene solution (around 5×10−5 mol/L) using a Hewlett-Packard 8453 diode array spectrometer. Steady state photoluminescent emission spectra were measured in dilute toluene at room temperature and in methyl cyclohexane (MeCy) at both room temperature and 77K on a Photon Technology International QuantaMaster model C-60 fluorimeter. Transient photoluminescent lifetimes were measured on an IBH Fluorocube instrument using time-correlated single-photon counting method (TCSPC) for those less than 100 ms and multichannel scaling method (MSC) for those longer than 100 ms. Photoluminescent quantum yields were determined using a Hamamatsu C9920 system equipped with a xenon lamp, calibrated integrating sphere and model C10027 photonic multichannel analyzer (PMA). Temperature-dependent lifetime measurements from 200 to 310 K were measured using IBH Fluorocube instrument in an OptistatDN Oxford cryostat. All fluid samples for luminescent measurements were deaerated by bubbling N2. Doped polymer films (1 wt %) were prepared in toluene solution of polystyrene (PS). The polymer solution with samples were dropcast onto a quartz substrate and the films were air-dried for 3 h and completely dried under vacuum. The emission properties of polymer samples were measured under a stream of N2 during the measurements.
Strickler Berg analysis of radiative rates: Strickler-Berg analysis, which has been proven successful for organic fluorophores, takes extinction spectral data to estimate oscillator strength for the transition between ground state and the first singlet excited state. Then, radiative decay rate for emission can be predicted in turn. The analysis requires the following data: absorption maximum in wavenumbers, integrated area of the S0-S1 transition in wavenumbers and the extinction coefficient in L mol−1 cm−1. Here, the integrated area is estimated by integrating half of the low energy ICT absorption band and double it numerically aiming to avoiding the overlap with the high-energy ligand-based absorption. The equation used is shown below:
k
ft=2.88×10−9ν02∫εdν
where kft is the predicted radiative decay rate, ν0 is the wavenumber of the absorption maximum, E is the molar extinction coefficient. The absorption spectra of all of the complexes in toluene are shown in
The absorption spectra in CH2Cl2 for the (carbene)Cu(carbazolyl) complexes are provided in
acalculated as a weighted average of the two contributions from a biexponential decay trace at emission maximum
Table 8 provides ΦPL values of the doped PS films under air and N2. Table 9 provides emission properties in toluene.
Full kinetic fits of the temperature dependent lifetime from 210 to 310 K for (carbene)Cu(carbazolyl) complexes are provided in
Table 10 provides complete photophysical properties of TADF coinage metal complexes. Relevant chemical structures are provided below the table. In the chemical structures, dipp refers to 2,6-diisopropylphenyl.
The relative PLQY DPL at different temperature is calculated according to the following equation
where A and A295K are the integrated emission spectra area at the corresponding temperature and 295K, respectively. ΦPL,295K is the absolute PLQY at 295K. The relative DPL in doped PS at different temperatures is are presented in Table 11.
The TADF decay rate as a function of NTO overlap is provided in
The relationship between calculated krS
References: a) H. Noda, et al., Nature Materials, 2019, 18, 1084-1090; b) H. Noda, et al., Science Advances, 2018, 4, 6910; c) L.-S. Cui, et al., Nature Photonics, 2020, 14, 636-642; d) Y. Kondo, et al., Nature Photonics, 2019, 13, 678-682; e) J. U. Kim, et al., Nature Communications, 2020, 11, 1765; f) N. Aizawa, et al., Advanced Optical Materials, 2020, 8, 19-01627; g) D. Hall, et al., Adv. Opt. Mater., 2020, 8, 1901627; h) Q. Zhang, et al., Nature Photonics, 2014, 8, 326-332; i) J. Lee, et al., Chem. Mater., 2017, 29, 8012-8020; j) S. Jeong, et al., Journal of Materials Chemistry C, 2018, 6, 9049-9054; k) I. S. Park, et al., Adv. Funct. Mater., 2018, 28, 1802031; m) S. Wang, et al., Angew. Chem. Int. Ed., 2015, 54, 13068-13072; n) K. Shizu, et al., The Journal of Physical Chemistry C, 2015, 119, 26283-26289; o) S. Hirata, et al., Nature Materials, 2015, 14, 330-336; p) T. Hatakeyama, et al., Adv. Mater., 2016, 28, 2777-2781; q) T.-A. Lin, et al., Adv. Mater., 2016, 28, 6976-6983; r) Q. Zhang, et al., Adv. Mater., 2015, 27, 2096-2100; s) J. Guo, et al., Adv. Funct. Mater., 2017, 27, 1606458; t) G. Xie, et al., Adv. Mater., 2016, 28, 181-187; u) H. Tanaka, et al., Chem. Commun., 2012, 48, 11392-11394.
This invention describes luminescent two-coordinate carbene-metal-amide/aryl (cMa) complexes where the carbene ligands are appended with electron acceptor groups. The donor can be either an amide or aryl ligand. The pi-appended carbene ligands are used to increase the radiative rate for luminescence. The cMa complexes can display highly efficient photoluminescence quantum yields from intramolecular charge transfer (ICT) states between the electron donor amide/aryl ligands and acceptor carbene ligands. Luminescence from the ICT state is characterized as thermally activated delayed fluorescence (TADF) since emission occurs from an ICT singlet state thermally populated from an energetically lower lying triplet state. The energy separation between single and triplet states (ΔEST) is an important parameter that controls the radiative rate for luminescence. The electronic interaction between single and triplet states is further enhanced by spin-orbit coupling (SOC) induced by bridging metal atom. The combined effects of a small ΔEST and SOC from the metal cause rapid intersystem crossing between the ICT singlet and triplet states that promotes fast radiative rates for emission (kτ>5×105 s−1). Fast radiative rates favor high photoluminescence efficiencies in TADF compounds. The current invention describes carbene ligands used in cMa complexes that minimize the energy separation between single and triplet states (ΔEST) while also maintaining a strong oscillator strength for singlet absorptivity. The most favorable situation occurs when the electron affinity of the appended electron acceptor group is greater than that of the parent unsubstituted carbene ligand.
The radiative rate for TADF is given by the following equation:
where HSOC is the SOC operator and μ is the dipole operator. A high oscillator strength for the S1→S0 transition (S0|μ|S1
) and efficiency intersystem crossing (
Tn|HSOC|S1
) and a low ΔEST are important to achieve a high TADF rate. The metal center ensures that the intersystem crossing rate will be fast. Thus, the TADF rate is largely governed by the oscillator strength and ΔEST, which need to be large and small, respectively, if a high TADF rate is to be achieved.
Examples of carbene ligands useful for making cMa complexes with pi-appended groups are shown in
In another embodiment (
The concepts behind the invention are illustrated in the figures at the end of this document that show the results of density functional theory (DFT) and time-dependent (TD) DFT calculations. The methods used are B3LYP/LACVP* for DFT and CAM-B3LYP/LACVP* for TDDFT calculations. The attenuation factor (Q) in the latter calculation was set to 0.20. These methods have been shown to accurately correlate with experimental values and trends in the optoelectronic properties of known derivatives (Shi, S., et al. J. Am. Chem. Soc. 2019, 141 (8), 3576-3588; Hamze, R., et al., Science 2019, 363 (6427), 601). In
Adding electron accepting groups to the periphery of the carbene ligand of a cMa complex can markedly alter the electronic structure of the complex. Appending a 4-pyridyl group to the imidazolyl ligand [(4-pyr-Me2imid)Cu(Cz)] alters the valence MOs as shown in
The key component of this invention is the observation that interligand charge transfer excited states in cMa complexes which involve significant mixing of the LUMO and a higher lying unoccupied MO in the transition leads to a decrease in ΔEST and only a marginal decrease in the oscillator strength, so long as one of the unoccupied MOs involved has substantial character on the carbene carbon bound to the metal ion. If this carbene carbon is not involved in the excited state both the ΔEST and the oscillator strength of the transition will be decreased. In order to have a high TADF rate the oscillator strength must be kept at a reasonable level or it will offset the benefits of decreasing ΔEST. Thus, acceptor substituted carbene ligands can be used to decrease ΔEST while maintaining a high oscillator strength, leading to high TADF radiative rates
Compounds 1, 2, and 3 were synthesized according to the reported method (T.-y. Li, et al, Chem. Eur. J. 2021, 27(20), 6191-6197; C. Zhang, et al. New J. Chem., 2017, 41, 1889-1892;
Synthesis of Carbene-Ag-OTf: 3 (1 equiv.) and Ag2O (0.6 equiv.) were stirred in anhydrous DCM at RT for 3 days. Remove the insoluble components by Celite. The carbene-Ag-OTf was obtained by adding excess amount of pentane into the condensed filtrate as grey crystalline.
Synthesis of Carbene-Au—Cl: To an anhydrous THF solution of 3 (1 equiv.), KHMDS (0.5M in toluene, 1.1 equiv.) was added dropwise at −77K. After 3 h, (Me2S)AuCl (1.1 equiv.) was added in one portion at −77K. The system is allowed to warm up to RT and stir for overnight. Remove the insoluble components by Celite. The carbene-Cu—Cl was obtained by adding excess amount of pentane into the condensed filtrate as white crystalline.
Synthesis of the Carbene-Metal-amide complexes: Carbazole or 3-cyano-carbazole (1 equiv.) and NaOtBu (1 equiv.) were dissolved in anhydrous THF and stir at RT for 2 h. Corresponding carbene-Metal intermediate complexes were added in one portion, and the solution was stirred at RT for overnight. Remove the insoluble components by Celite. Excess amount of pentane was added into the condensed filtrate. The final product was collected as crystalline powder and washed by ether or methanol.
PhCu*: 1H NMR (400 MHz, acetone) δ 8.16 (s, 1H), 7.89 (t, J=7.9 Hz, 2H), 7.81 (t, J=7.8 Hz, 1H), 7.64 (d, J=7.8 Hz, 2H), 7.51 (t, J=6.6 Hz, 2H), 7.49-7.44 (m, 1H), 7.40 (dd, J=8.7, 5.3 Hz, 4H), 7.11 (dd, J=8.5, 1.5 Hz, 1H), 6.98 (t, J=7.1 Hz, 1H), 6.89 (t, J=7.3 Hz, 1H), 6.83 (s, 1H), 5.65 (d, J=8.1 Hz, 1H), 5.54 (d, J=8.5 Hz, 1H), 3.15 (dtd, J=20.4, 13.5, 6.7 Hz, 4H), 1.29 (t, J=7.3 Hz, 12H), 1.24 (d, J=6.8 Hz, 6H), 1.19 (d, J=6.7 Hz, 6H).
PhAg: 1H NMR (400 MHz, acetone) δ 7.85-7.70 (m, 4H), 7.60 (d, J=7.8 Hz, 2H), 7.53-7.46 (m, 3H), 7.45-7.38 (m, 4H), 6.92 (ddd, J=8.2, 7.0, 1.2 Hz, 2H), 6.87 (s, 1H), 6.78-6.69 (m, 2H), 6.02 (d, J=8.1 Hz, 2H), 3.26-2.99 (m, 4H), 1.35 (d, J=6.8 Hz, 6H), 1.29 (dd, J=12.4, 6.8 Hz, 12H), 1.15 (d, J=6.7 Hz, 6H).
PhAu: 1H NMR (400 MHz, acetone) δ 7.85-7.71 (m, 4H), 7.58 (d, J=7.8 Hz, 2H), 7.50-7.42 (m, 3H), 7.38 (d, J=4.4 Hz, 4H), 6.93 (ddd, J=8.2, 7.0, 1.3 Hz, 2H), 6.86 (s, 1H), 6.77 (ddd, J=7.9, 7.1, 1.0 Hz, 2H), 6.05 (dt, J=8.2, 0.8 Hz, 2H), 3.07 (sept, J=6.7 Hz, 4H), 1.41 (d, J=6.8 Hz, 6H), 1.32 (d, J=6.8 Hz, 6H), 1.26 (d, J=6.8 Hz, 6H), 1.11 (d, J=6.7 Hz, 6H).
PhAu*: 1H NMR (400 MHz, acetone) δ 8.23 (dd, J=1.7, 0.6 Hz, 1H), 7.97-7.92 (m, 1H), 7.84 (dt, J=20.4, 7.8 Hz, 2H), 7.62 (d, J=7.8 Hz, 2H), 7.54-7.45 (m, 3H), 7.41 (d, J=4.3 Hz, 4H), 7.22 (dd, J=8.5, 1.7 Hz, 1H), 7.08 (ddd, J=8.3, 7.1, 1.3 Hz, 1H), 6.94 (ddd, J=8.0, 7.1, 1.0 Hz, 1H), 6.91 (s, 1H), 6.13 (dd, J=8.2, 0.8 Hz, 1H), 6.05 (dd, J=8.5, 0.6 Hz, 1H), 3.18-3.00 (m, 4H), 1.42 (d, J=6.8 Hz, 6H), 1.32 (d, J=6.8 Hz, 6H), 1.27 (d, J=6.8 Hz, 6H), 1.13 (d, J=6.7 Hz, 6H).
The molecular structures of the two coordinate coinage metal complexes with extended phenyl substitutes in carbene ligands are shown below. The absorption spectra in toluene are presented in
It is understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore include variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting.
The present application claims priority to U.S. Provisional Application No. 63/298,943, filed Jan. 12, 2022, and U.S. Provisional Application No. 63/222,523, filed Jul. 16, 2021, all of which are incorporated by reference herein in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 63222523 | Jul 2021 | US | |
| 63298943 | Jan 2022 | US |
