Thermally activated delayed fluorescence (TADF) materials for high efficiency organic photovoltaics

Abstract

The invention relates to thermally activated delayed fluorescence (TADF) materials for high efficiency organic photovoltaics. An organic photovoltaic device is described comprising an anode; a cathode; and a photoactive organic material in a layer disposed between the anode and the cathode; an energy difference ([delta] EST) between a triplet energy state (T1) and a singlet energy state (S1) in the photoactive organic material is less than about 300 meV; and when the organic photovoltaic device is irradiated with light having an AM 1.5 spectrum, the open circuit voltage of the organic photovoltaic device is greater than 0.9 V, the power conversion efficiency is greater than 22%, and the EL external quantum efficiency is gt; 5%.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 667,363, filed Jul. 3, 2024, and U.S. Provisional Application No. 63 / 592,252, filed Oct. 23, 2023; each of the U.S. Provisional Applications is hereby incorporated by reference in its entirety.

[0003] Statement Regarding Federally Sponsored Research or Development

[0004] This invention was made with government support under DE-EE0008561 awarded by the U.S. Department of Energy. The government has certain rights in this invention. Technical Field

[0005] The present disclosure generally relates to electroactive, photoactive, solar, and semiconductor devices, and in particular, to organic photovoltaic cell units and compositions in such organic photovoltaic cell units. Background Art

[0006] Optoelectronic devices rely on the optical and electronic properties of materials to electronically generate or detect electromagnetic radiation, or generate electricity from ambient electromagnetic radiation.

[0007] Photosensitive optoelectronic devices convert electromagnetic radiation into electricity. Solar cell units (also referred to as photovoltaic (PV) devices or cell units) are a type of photosensitive optoelectronic device specifically designed to generate electricity. PV devices that can generate electrical energy from light sources other than sunlight can be used to drive power-consuming loads to provide, for example, lighting, heating, or power electronic circuitry or devices such as calculators, radios, computers, or remote monitoring or communication equipment. These power generation applications can involve charging batteries or other energy storage devices so that operation can continue when direct illumination from the sun or other light sources is unavailable, or balancing the power output of the PV device with the requirements of a particular application.

[0008] Traditionally, photosensitive optoelectronic devices have been constructed from many inorganic semiconductors (e.g., crystalline, polycrystalline, and amorphous silicon, gallium arsenide, cadmium telluride, etc.).

[0009] More recently, increased efforts have focused on using organic photovoltaic (OPV) cell units to achieve acceptable photovoltaic conversion efficiency with an economical production cost. OPV offers a low-cost, lightweight, and mechanically flexible approach for solar energy conversion. Compared to polymers, small molecule OPV has the advantage of using materials with well-defined molecular structures and weights. This results in reliable purification routes and the ability to deposit multiple layers using highly controlled thermal deposition without concern for dissolution and thereby damaging previously deposited layers or sub-cell units.

[0010] In addition to pursuing high device efficiency, OPV also has unique advantages, such as semi-transparent solar cell units being applied to building-integrated photovoltaics (BIPV). Considering the huge surface area of windows and facades in modern urban environments, it has become increasingly important to develop semi-transparent solar cell units with both high efficiency and high transmittance. For a solar cell unit to be highly transparent, visible light will have to travel unimpeded to the eye and thus cannot be absorbed. Selectively harvesting near-infrared (NIR) radiation avoids the competition between efficiency and transmittance. However, the lack of high-performance NIR absorbers in traditional fullerene-based OPVs has hindered the attainment of efficient but highly transparent (in visible light) devices. So far, semi-transparent OPVs based on fullerene acceptors have only shown a PCE less than or equal to 4% and an average visible light transmittance of 61%. Summary of the Invention

[0011] In one aspect, the present disclosure relates to an organic photovoltaic device comprising:

[0012] An anode;

[0013] A cathode; and

[0014] A photoactive organic material located in a layer disposed between the anode and the cathode;

[0015] Wherein:

[0016] The energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) in the photoactive organic material is less than about 300 meV; and

[0017] When the organic photovoltaic device is irradiated with light having an AM1.5 spectrum, the open-circuit voltage of the organic photovoltaic device is greater than 0.9 V, and the power conversion efficiency is greater than 22%, and the external quantum efficiency of EL > 5%. Brief Description of the Drawings

[0018] To more fully understand the present disclosure, reference is made to the following detailed description and the drawings, in which like reference numerals may be used to identify like elements in the drawings.

[0019] Figure 1 Depicts an exemplary organic photovoltaic device 100.

[0020] Figure 2 Depicts an exemplary organic photovoltaic device 200.

[0021] Figure 3Depicts the charge separation and recombination processes in a conventional OPV cell unit. ΔE 1 is the thermalization loss, ΔE 2 is the exciton dissociation loss, and ΔE 3 is the radiative and non-radiative recombination loss.

[0022] Figure 4 Is a comparison of an organic solar cell unit of the prior art with inorganic technology. Voltage loss is a limiting factor for OPV to achieve efficiency.

[0023] Figure 5 Depicts a prior art stable NFA-based OPV with an ultrathin (2 nm) C 70 and a single-layer IC-SAM interfacial buffer.

[0024] Figure 6 Depicts exemplary self-assembled anode and cathode buffer layer materials.

[0025] Figure 7 Is a graph of the extrapolated degradation of a population of NFA-based OPVs under ALT conditions of 1 - 27 suns. T 80 is the time when the efficiency drops to 80% of its initial value. In this case, its extrapolated value under 1 sun illumination is 30 years.

[0026] Figure 8 Is a schematic structure of a 15% efficient organic tandem cell unit.

[0027] Figure 9 Is an optical model that absorbs the AM1.5G reference spectrum. The red dashed line indicates the charge recombination region connecting the top cell unit and the bottom cell unit.

[0028] Figure 10 Is a series of graphs showing Figure 8 the performance of the tandem cell unit depicted.

[0029] Figure 11 Is a depiction of how the 2,2'-dipyrromethene structural features are present in the molecules of interest. The synthetic ease increases as the structural complexity decreases from bridged dipyrrole to BODIPY.

[0030] Figure 12 Is a depiction of the donor group, acceptor group, and alkyl chain of compound Y6. Detailed Description

[0031] The present disclosure provides non-fullerene acceptors (NFAs) having good photo-stability and morphological stability. In some aspects, these NFAs are employed in one or more device architectures to achieve OPV devices with improved operational lifetimes.

[0032] Various non-limiting examples of OPV and the compositions within each layer of OPV are described in more detail below.

[0033] Definitions

[0034] As used herein, the term "organic material" includes polymeric materials and small molecule organic materials that can be used to fabricate organic optoelectronic devices. "Small molecule" refers to any organic material that is not a polymer, and a "small molecule" can actually be quite large. In some cases, small molecules can include repeating units. For example, using a long-chain alkyl as a substituent does not remove the molecule from the "small molecule" category. Small molecules can also be incorporated into polymers, such as as side groups on the polymer backbone or as part of the backbone. Small molecules can also be used as the core portion of a dendrimer, which consists of a series of chemical shells built on the core portion. The core portion of a dendrimer can be a fluorescent or phosphorescent small molecule emitter. Dendrimers can be "small molecules", and it is believed that all dendrimers currently used in the OLED field are small molecules.

[0035] As used herein, "top" means furthest from the substrate, and "bottom" means closest to the substrate. In the case where a first layer is described as being "disposed" above a second layer, the first layer is disposed further from the substrate. Unless it is specified that the first layer is "in contact with" the second layer, there can be other layers between the first layer and the second layer. For example, the cathode can be described as being "disposed on" the anode, even though there are various organic layers therebetween.

[0036] As used herein, "solution processable" means capable of being dissolved, dispersed, or transported in a liquid medium in solution or suspension form and / or capable of being deposited from a liquid medium.

[0037] When a ligand is considered to directly contribute to the photoactive properties of an emissive material, the ligand can be referred to as "photoactive". When a ligand is not considered to contribute to the photosensitive properties of an emissive material, the ligand can be referred to as "auxiliary", but an auxiliary ligand can modify the properties of a photosensitive ligand.

[0038] As used herein, the terms "electrode" and "contact" can refer to a layer that provides a medium for delivering current to an external circuit or providing a bias current or voltage to a device. For example, an electrode or contact can provide an interface between the active region of an organic photosensitive optoelectronic device and a wire, lead, trace, or other device for transporting charge carriers to or from an external circuit. Examples of electrodes include anodes and cathodes that can be used in photosensitive optoelectronic devices.

[0039] As used herein, the term "light transmissive" may refer to a material that permits at least 50% of the incident electromagnetic radiation in a relevant wavelength to pass therethrough. In a photosensitive type of optoelectronic device, it may be desirable to allow the maximum amount of ambient electromagnetic radiation from outside the device to be permitted to enter the optically active interior region. That is, the electromagnetic radiation must reach the light guiding layer, where the electromagnetic radiation can be converted into electricity by light guiding absorption. This generally requires that at least one of the electrical contacts or electrodes should absorb and reflect the incident electromagnetic radiation minimally. In some cases, this contact should be light transmissive or at least semi - light transmissive. In one embodiment, a light transmissive material may form at least a part of the electrical contact or electrode.

[0040] As used herein, the term "semi - light transmissive" may refer to a material that permits some but less than 50% of the ambient electromagnetic radiation in a relevant wavelength to pass through. When using a light transmissive or semi - light transmissive electrode, the opposing electrode may be a reflective material such that the light that passes through the cell unit without being absorbed is reflected back through the cell unit.

[0041] As used and depicted herein, a "layer" refers to a member or component of a device (such as an optoelectronic device) that is primarily defined by its thickness (e.g., relative to other adjacent layers) and extends outwardly in length and width. It should be understood that the term "layer" is not necessarily limited to a single material layer or sheet. Additionally, it should be understood that the surface of certain layers (including the interfaces of these layers with other materials or layers) may be imperfect, where the surface represents an interpenetrating, entangled, or convolutional network with other materials or layers. Similarly, it should also be understood that a layer may be discontinuous such that the continuity of the layer along its length and width may be disrupted or otherwise interrupted by other layers or materials.

[0042] As used herein, an "optically active region" refers to a region of a device that absorbs electromagnetic radiation to generate excitons. Similarly, if a layer absorbs electromagnetic radiation to generate excitons, then the layer is "optically active". Excitons can dissociate into electrons and holes to generate an electric current.

[0043] As used herein, the terms "donor" and "acceptor" refer to the relative positions of the highest occupied molecular orbital ("HOMO") energy levels and the lowest unoccupied molecular orbital ("LUMO") energy levels of two contacting but different organic materials. If the LUMO energy level of one material is lower when it contacts another material, then the material is an acceptor. Otherwise, the material is a donor. In the absence of an external bias, it is energetically favorable for electrons at a donor - acceptor junction to move into the acceptor material, and for holes, it is energetically favorable to move into the donor material.

[0044] As used herein, the term "bandgap" (E g ) of a polymer can refer to the energy difference between the HOMO and the LUMO. The bandgap is typically expressed in electron volts (eV). The bandgap can be measured by UV-vis spectroscopy or cyclic voltammetry. A "low bandgap" polymer can refer to a polymer having a bandgap below 2 eV. For example, the polymer absorbs light with a wavelength longer than 620 nm.

[0045] As used herein, the term "excitation binding energy" (E B ) can refer to the following formula: E B =(M + +M - )–(M*+M), where M + and M - are the total energies of the positively charged molecule and the negatively charged molecule, respectively; M* and M are the molecular energies in the first singlet state (S 1 ) and the ground state, respectively. The excitation binding energy of the acceptor molecule or the donor molecule affects the energy offset required for efficient exciton dissociation. In certain instances, the escape yield of holes increases as the HOMO offset increases. A decrease in the exciton binding energy E B of the acceptor molecule results in an increase in the escape yield of holes for the same HOMO offset between the donor molecule and the acceptor molecule.

[0046] As used herein, the "power conversion efficiency" (PCE) (η ρ ) can be expressed as:

[0047]

[0048] where V OC is the open-circuit voltage, FF is the fill factor, J SC is the short-circuit current, and P O is the input optical power.

[0049] As used herein, "spin coating" can refer to a process of depositing a layer or film solution of a material (i.e., a coating material) on the surface of an adjacent substrate or material layer. The spin coating process can include applying a small amount of the coating material to the center of the substrate, which spins at a low speed or does not spin at all. Then the substrate is rotated at a high speed to cause the coating material to spread by centrifugal force. Rotation continues until the film reaches the desired thickness as the fluid spins off the edge of the substrate. The solvent applied is typically volatile and evaporates simultaneously. Therefore, the higher the angular velocity of the spin, the thinner the film. The thickness of the film also depends on the viscosity and concentration of the solution and the solvent.

[0050] As used herein, and as would be generally understood by one of ordinary skill in the art, if the first energy level is closer to the vacuum energy level, then the first "highest occupied molecular orbital" (HOMO) energy level or "lowest unoccupied molecular orbital" (LUMO) energy level is "greater than" or "higher than" the second HOMO energy level or LUMO energy level. Since the ionization potential (IP) is measured as a negative energy relative to the vacuum energy level, a higher HOMO energy level corresponds to an IP with a smaller absolute value (a less negative IP). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) with a smaller absolute value (a less negative EA). On a conventional energy level diagram with the vacuum energy level at the top, the LUMO energy level of a material is higher than the HOMO energy level of that material. A "higher" HOMO or LUMO energy level appears closer to the top of this diagram than a "lower" HOMO or LUMO energy level.

[0051] As used herein, and as would be generally understood by one of ordinary skill in the art, if the absolute value of the first work function is higher, then the first work function is "greater than" or "higher than" the second work function. Since the work function is typically measured as a negative number relative to the vacuum energy level, this means that a "higher" work function is more negative. On a conventional energy level diagram with the vacuum energy level at the top, a "higher" work function is illustrated as being further from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow different rules than the work function.

[0052] Details regarding OLEDs and the definitions described above can be found in U.S. Patent No. 7,279,704, which is incorporated herein by reference in its entirety.

[0053] The terms "halo", "halogen", and "halide" are used interchangeably and refer to fluorine, chlorine, bromine, and iodine.

[0054] The term "pseudohalogen" refers to polyatomic analogs of halogens whose chemistry is similar to that of true halogens, allowing them to substitute for halogens in several classes of chemical compounds. Exemplary pseudohalogens include, but are not limited to, nitriles, cyaphides, isocyanides, cyanates, isocyanates, fulminates, thiocyanates, isothiocyanates, selenocyanates, tellurocyanates, azides, tetracarbonylcobaltates, trinitromethanides, and tricyanomethanide groups.

[0055] The term "acyl" refers to a substituted carbonyl (C(O)–R s ).

[0056] The term "ester" refers to a substituted oxycarbonyl (–O–C(O)–R s or –C(O)–O–R s ).

[0057] The term "ether" refers to an –OR s group.

[0058] The terms "thioalkyl" or "thioether" are used interchangeably and refer to an –SR s group.

[0059] The term "sulfinyl" refers to an –S(O)–R s group.

[0060] The term "sulfonyl" refers to an –SO 2 –R s group.

[0061] The term "phosphino" refers to a –P(R s ) 3 group, where each R s can be the same or different.

[0062] The term "silyl" refers to a –Si(R s ) 3 group, where each R s can be the same or different.

[0063] The term "boryl" refers to a –B(R s ) 2 group or its Lewis adduct –B(R s ) 3 group, where R s can be the same or different.

[0064] In each of the above, R s 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 combinations thereof. Preferred R s is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.

[0065] The term "alkyl" refers to and includes both straight-chain alkyls and branched-chain alkyls. Preferred alkyls are groups containing one to fifteen carbon atoms and include 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, etc. Additionally, the alkyl is optionally substituted.

[0066] The term "cycloalkyl" means and includes monocyclic, polycyclic and spirocycloalkyl groups. Preferred cycloalkyl groups are those containing from 3 to 12 ring carbon atoms and include cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[3.1.1]heptyl, spiro[4.5]decyl, spiro[5.5]undecyl, adamantyl, etc. Additionally, the cycloalkyl group is optionally substituted.

[0067] The term "heteroalkyl" or "heterocycloalkyl" means an alkyl or cycloalkyl group, respectively, having at least one carbon atom substituted by a heteroatom. Optionally, at least one heteroatom is selected from O, S, N, P, B, Si and Se, preferably O, S or N. Additionally, the heteroalkyl or heterocycloalkyl group is optionally substituted.

[0068] The term "alkenyl" means and includes both straight-chain and branched-chain alkenyl groups. An alkenyl group is essentially an alkyl group having at least one carbon-carbon double bond in the alkyl chain. A cycloalkenyl group is essentially a cycloalkyl group having at least one carbon-carbon double bond in the cycloalkyl ring. As used herein, the term "heteroalkenyl" means an alkenyl group having at least one carbon atom substituted by a heteroatom. Optionally, 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 from two to fifteen carbon atoms. Additionally, the alkenyl, cycloalkenyl or heteroalkenyl group is optionally substituted.

[0069] The term "alkynyl" means and includes both straight-chain and branched-chain alkynyl groups. Preferred alkynyl groups are those containing from two to fifteen carbon atoms. Additionally, the alkynyl group is optionally substituted.

[0070] The terms "aralkyl" or "arylalkyl" are used interchangeably and mean an alkyl group substituted by an aryl group. Additionally, the aralkyl group is optionally substituted.

[0071] The term "heterocyclic group" means and includes aromatic and non-aromatic ring groups containing at least one heteroatom. Optionally, at least one heteroatom is selected from O, S, N, P, B, Si and Se, preferably O, S or N. Heteroaromatic ring groups can be used interchangeably with heteroaryl groups. Preferred heteronon-aromatic ring groups are those containing from 3 to 7 ring atoms, which include at least one heteroatom and include cyclic amines (such as morpholinyl, piperidinyl, pyrrolidinyl, etc.) and cyclic ethers / sulfides (such as tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, etc.). Additionally, the heterocyclic group can be optionally substituted.

[0072] The term "aryl" refers to and includes both monocyclic aromatic hydrocarbon groups and polycyclic aromatic ring systems. The polycyclic rings can have two or more rings, where two carbons are common to two adjacent rings (the rings are "fused"), and at least one of the rings is an aromatic hydrocarbon group. For example, the other rings can be cycloalkyl, cycloalkenyl, aryl, heterocyclic, and / or heteroaryl. Preferred aryl groups are those containing six to thirty carbon atoms, preferably six to twenty carbon atoms, more preferably six to twelve carbon atoms. Particularly preferred are aryl groups having six, ten, or twelve carbon atoms. Suitable aryl groups include phenyl, diphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, perylene, and azulene, preferably phenyl, diphenyl, triphenyl, triphenylene, fluorene, and naphthalene. Additionally, the aryl group is optionally substituted.

[0073] The term "heteroaryl" refers to and includes both monocyclic aromatic groups containing at least one heteroatom and polycyclic aromatic ring systems. Heteroatoms include, but are not limited to, O, S, N, P, B, Si, and Se. In many cases, O, S, or N are preferred heteroatoms. The heterocyclic - monocyclic aromatic system is preferably a single ring having 5 or 6 ring atoms, and the ring can have one to six heteroatoms. The heterocyclic - polycyclic ring system can have two or more rings, where two atoms are common to two adjacent rings (the rings are "fused"), and at least one of the rings is a heteroaryl. For example, the other rings can be cycloalkyl, cycloalkenyl, aryl, heterocyclic, and / or heteroaryl. The heterocyclic - polycyclic aromatic ring system can have 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, pyrrolodipyrimidine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indolizine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuranopyridine, furandipyridine, benzothiophenopyridine, thiophenedipyridine, benzoselenophenopyridine, and selenophenedipyridine. Preferably, dibenzothiophene, dibenzofuran, dibenzoselenol, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, 1,2 - azaborine, 1,3 - azaborine, 1,4 - azaborine, borazine, and their nitrogen analogs. Further, the heteroaryl group is optionally substituted.

[0074] Among the aryl and heteroaryl groups listed above, groups of triphenylene, naphthalene, anthracene, dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, pyrazine, pyrimidine, triazine, and benzimidazole and the corresponding azo analogs of each thereof are of particular interest.

[0075] As used herein, the terms alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aralkyl, heterocyclic group, aryl, and heteroaryl are independently unsubstituted or independently substituted with one or more common substituents.

[0076] In many cases, the common 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, cyano, isocyano, thioalkyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

[0077] In some cases, the preferred common substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, cyano, isocyano, thioalkyl, and combinations thereof.

[0078] In some cases, the preferred common substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, thioalkyl, and combinations thereof.

[0079] In still other cases, the more preferred common substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.

[0080] The terms "substituted" and "substitution" refer to substituents bonded to the relevant position (e.g., carbon or nitrogen) other than H. For example, when R 1 represents monosubstitution, then one R 1 must be non-H (i.e., substituted). Similarly, when R 1 represents disubstitution, then both of the R 1 must be non-H. Similarly, when R 1 represents unsubstitution, for example, for the available valences of ring atoms (such as the carbon atoms of benzene and the nitrogen atom of pyrrole), R 1 can be hydrogen, or for a ring atom with a fully filled valence (e.g., the nitrogen atom in pyridine), it simply does not represent anything. The maximum number of possible substitutions in the ring structure will depend on the total number of available valences in the ring atoms.

[0081] As used herein, "their combination" means combining one or more members of an applicable list to form a known or chemically stable arrangement that can be envisioned by one of ordinary skill in the art based on the applicable list. For example, an alkyl group and deuterium can be combined to form a partially or fully deuterated alkyl group; a halogen and an alkyl group can be combined to form a halogenated alkyl substituent; and a halogen, an alkyl group, and an aryl group can be combined to form a halogenated arylalkyl group. In one instance, the term substitution includes combinations of two to four of the listed groups. In another instance, the term substitution includes combinations of two to three groups. In yet another instance, the term substitution includes combinations of two groups. Preferred combinations of substituents are groups containing up to fifty atoms that are not hydrogen or deuterium, or groups including up to forty atoms that are not hydrogen or deuterium or groups including up to thirty atoms that are not hydrogen or deuterium. In many cases, the preferred combination of substituents will include up to twenty atoms that are not hydrogen or deuterium.

[0082] The "aza" names (i.e., aza-dibenzofuran, aza-dibenzothiophene, etc.) in the fragments described herein mean that one or more of the C-H groups in the corresponding aromatic ring can be replaced by a nitrogen atom. For example, and without any limitation, azatriphenylene encompasses both dibenzo[f,h]quinoxaline and dibenzo[f,h]quinoline. 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 described herein.

[0083] 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. Patent No. 8,557,400, Patent Publication No. WO 2006 / 095951, and U.S. Patent Publication No. US2011 / 0037057 describe the preparation of deuterium-substituted organometallic complexes, which are hereby incorporated by reference in their entirety. 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 hereby incorporated by reference in their entirety, which describe the deuteration of methylene hydrogens in aniline and efficient pathways for replacing aromatic ring hydrogens with deuterium, respectively.

[0084] It should be understood that when a molecular fragment is described as a substituent or otherwise attached to another fragment, its name can be written as if it were a fragment (e.g., phenyl, phenylene, naphthyl, dibenzofuranyl) or as if it were the entire molecule (e.g., benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating substituents or attached fragments are considered to be equivalent.

[0085] In some instances, adjacent substituent pairs can optionally be linked or fused to form a ring. Preferred rings are five-, six- or seven-membered carbocyclic or heterocyclic rings, including cases where the portion of the ring formed by the substituent pair is saturated and cases where the portion of the ring formed by the substituent pair is unsaturated. As used herein, "adjacent" means that the two substituents involved can be located next to each other on the same ring, or on two adjacent rings having two nearest available substitution positions (such as the 2,2'-positions in biphenyl, or the 1,8-positions in naphthalene), provided that the rings can form a stable fused-ring system.

[0086] Unless otherwise specified, any layer in the layers of the various embodiments can be deposited by any suitable method. For organic layers, preferred methods include thermal evaporation, inkjet (as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entirety), organic vapor phase deposition (OVPD) (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) (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 other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding (as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entirety), and patterning associated with some of the deposition methods such as inkjet and organic vapor jet printing (OVJP). Other methods can also be used. The materials to be deposited can be modified to make them compatible with the specific deposition method. For example, branched or unbranched substituents (such as alkyl and aryl) containing at least 3 carbons can be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 or more carbons can be used, and a range of 3-20 carbons is preferred. The solution processability of materials having an asymmetric structure can be better than that of materials having a symmetric structure because the tendency for recrystallization of asymmetric materials can be lower. Dendrimer substituents can be used to enhance the solution processability of small molecules.

[0087] Devices fabricated in accordance with embodiments of the present invention may further optionally include a barrier layer. One use of the barrier layer is to protect the electrodes and organic layers from damage by harmful substances in an environment that includes moisture, vapor, and / or gas. The barrier layer may be deposited on a substrate, above, below, or beside an electrode, or above any other part of the device, including the edges. The barrier layer may include 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 and compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate inorganic compounds or organic compounds or both. Preferred barrier layers include a mixture of a polymeric material and a non-polymeric material, as described in U.S. Patent No. 7,968,146, PCT Patent Application Nos. PCT / US2007 / 023098 and PCT / US2009 / 042829, which are incorporated herein by reference in their entirety. For the purpose of being considered a "mixture", the foregoing polymeric material and non-polymeric material that comprise the barrier layer should be deposited under the same reaction conditions and / or simultaneously. The weight ratio of the polymeric material to the non-polymeric material may range from 95:5 to 5:95. The polymeric material and the non-polymeric material may be produced from the same precursor material. In one example, the mixture of the polymeric material and the non-polymeric material consists substantially of polymeric silicon and inorganic silicon.

[0088] Devices fabricated in accordance with embodiments of the present invention may be incorporated into a wide variety of electronic component modules (or units), which may be incorporated into a wide variety of electronic products or intermediate components.

[0089] The materials and structures described herein may be applied to devices other than organic solar cell units. For example, other optoelectronic devices such as organic light emitting diodes (OLEDs) and organic photodetectors may employ the materials and structures. More generally, organic devices such as organic transistors may employ the materials and structures.

[0090] Organic photovoltaic cell unit

[0091] In one aspect, the present disclosure relates to an OPV device that includes a compound disclosed herein. In one embodiment, the OPV device includes an anode; a cathode; and an active material positioned between the anode and the cathode. In one embodiment, the active material includes a receptor and a donor.

[0092] In one embodiment, the OPV device includes a single-junction organic photovoltaic device 100 having a non-fullerene receptor compound Figure 1)。In one embodiment, the OPV device comprises two electrodes having an anode 102 and a cathode 104 in a stacked relationship, at least one donor composition, and at least one acceptor composition, wherein a donor-acceptor material or an active layer 106 is positioned between the two electrodes 102 and 104. In one embodiment, one or more intermediate layers 108 may be positioned between the anode 102 and the active layer 106. Additionally or alternatively, one or more intermediate layers 110 may be positioned between the active layer 106 and the cathode 104.

[0093] In one embodiment, the anode 102 comprises a conductive oxide, a thin metal layer, or a conductive polymer. In one embodiment, the anode 102 comprises a conductive metal oxide. Exemplary conductive metal oxides include, but are not limited to, indium tin oxide (ITO), tin oxide (TO), gallium indium tin oxide (GITO), zinc oxide (ZO), and zinc indium tin oxide (ZITO). In one embodiment, the anode 102 comprises a metal layer. Exemplary metals for the metal layer include, but are not limited to, Ag, Au, Pd, Pt, Ti, V, Zn, Sn, Al, Co, Ni, Cu, Cr, and combinations thereof. In one embodiment, the metal layer comprises a thin metal layer. In one embodiment, the anode 102 comprises a conductive polymer. Exemplary conductive polymers include, but are not limited to, polyaniline (PANI) or 3,4-polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS). In one embodiment, the thickness of the anode 102 ranges from about 0.1 - 100 nm. In one embodiment, the thickness of the anode 102 ranges from about 1 - 10 nm. In one embodiment, the thickness of the anode 102 ranges from about 0.1 - 10 nm. In one embodiment, the thickness of the anode 102 ranges from about 10 - 100 nm. In one embodiment, the anode 102 comprises a light-transmissive or semi-light-transmissive conductive material.

[0094] In one embodiment, the cathode 104 comprises a conductive oxide, a metal layer, or a conductive polymer. Exemplary conductive oxides, metal layers, and conductive polymers are described elsewhere herein. In one embodiment, the cathode comprises a thin metal layer. In one embodiment, the cathode 104 comprises a metal or a metal alloy. In one embodiment, the cathode 104 may comprise Ca, Al, Mg, Ti, W, Ag, Au, or another suitable metal or an alloy thereof. In one embodiment, the thickness of the cathode 104 ranges from about 0.1 - 100 nm. In one embodiment, the thickness of the cathode 104 ranges from about 1 - 10 nm. In one embodiment, the thickness of the cathode 104 ranges from about 0.1 - 10 nm. In one embodiment, the thickness of the cathode 104 ranges from about 10 - 100 nm. In one embodiment, the cathode 104 comprises a light-transmissive or semi-light-transmissive conductive material.

[0095] In one embodiment, the OPV device can include one or more charge collection / transport intermediate layers positioned between electrodes 102, 104 and the active region or layer 106. In one embodiment, the OPV device includes intermediate layer 108. In one embodiment, the OPV device includes intermediate layer 110. In one embodiment, the OPV device includes both intermediate layers 108 and 110. In one embodiment, intermediate layer 108 includes a metal oxide. In one embodiment, intermediate layer 110 includes a metal oxide. Exemplary metal oxides include but are not limited to MoO 3 , V 2 O 5 , ZnO and TiO 2 . In one embodiment, the first intermediate layer 108 has the same composition as the second intermediate layer 110. In one embodiment, the first intermediate layer 108 and the second intermediate layer 110 have different compositions. In one embodiment, the thicknesses of intermediate layer 108 and intermediate layer 110 each independently range from about 0.1 - 100 nm. In one embodiment, the thicknesses of intermediate layer 108 and intermediate layer 110 each independently range from about 1 - 10 nm. In one embodiment, the thicknesses of intermediate layer 108 and intermediate layer 110 each independently range from about 0.1 - 10 nm. In one embodiment, the thicknesses of intermediate layer 108 and intermediate layer 110 each independently range from about 10 - 100 nm.

[0096] In one embodiment, the OPV device includes each layer of the tandem or multi - junction photovoltaic device 200 having a non - fullerene acceptor compound ( Figure 2 ). In one embodiment, the OPV device includes two electrodes having an anode 202 and a cathode 204 in a stacked relationship, at least one donor composition, and at least one acceptor composition, the at least one donor composition and the at least one acceptor composition being positioned within a plurality of active layers or regions 206A and 206B located between the two electrodes 202 and 204. Other active layers or regions are possible. In one embodiment, anode 202 and cathode 204 each independently include a conductive oxide, a thin metal layer, or a conductive polymer. Exemplary conductive oxides, metal layers, and conductive polymers are described elsewhere herein.

[0097] In one embodiment, the OPV device includes one or more intermediate layers 208 positioned between the anode 202 and the first active layer 206A. Additionally or alternatively, at least one intermediate layer 210 may be positioned between the second active layer 206B and the cathode 204. In one embodiment, the OPV device includes one or more intermediate layers 212 positioned between the first active layer 206A and the second active layer 206B. In one embodiment, the OPV device includes the intermediate layer 208. In one embodiment, the OPV device includes the intermediate layer 210. In one embodiment, the OPV device includes the intermediate layer 212. In one embodiment, the OPV device includes both the intermediate layers 208 and 210. In one embodiment, the OPV device includes both the intermediate layers 208 and 212. In one embodiment, the OPV device includes both the intermediate layers 210 and 212. In one embodiment, the OPV device includes the intermediate layers 208, 210, and 212. In one embodiment, the intermediate layer 208 includes a metal oxide. In one embodiment, the intermediate layer 210 includes a metal oxide. In one embodiment, the intermediate layer 212 includes a metal oxide. Exemplary metal oxides are described elsewhere herein. Exemplary thicknesses of the intermediate layers 208, 210, and 212 are described elsewhere herein.

[0098] According to one aspect, the present disclosure relates to an organic photovoltaic device comprising:

[0099] An anode;

[0100] A cathode; and

[0101] A photoactive organic material disposed in a layer disposed between the anode and the cathode;

[0102] Wherein:

[0103] The energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) in the photoactive organic material is less than about 300 meV; and

[0104] When the organic photovoltaic device is irradiated with light having an AM1.5 spectrum, the open-circuit voltage of the organic photovoltaic device is greater than 0.9 V, the power conversion efficiency is greater than 22%, and the EL external quantum efficiency > 5%.

[0105] In one embodiment, the energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) is less than about 100 meV. In one embodiment, ΔE ST is less than about 150 meV. In one embodiment, ΔEST Less than about 200 meV. In one embodiment, ΔE ST Less than about 250 meV. In one embodiment, ΔE ST Less than about 300 meV. In one embodiment, ΔE ST Less than about 350 meV. In one embodiment, ΔE ST Less than about 400 meV. In one embodiment, ΔE ST Less than about 450 meV. In one embodiment, ΔE ST Less than about 500 meV.

[0106] In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than 0.9 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 0.5 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 0.6 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 0.7 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 0.8 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 0.9 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light is greater than about 1.0 V.

[0107] In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than 0.9 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 0.5 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 0.6 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 0.7 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 0.8 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 0.9 V. In one embodiment, the open-circuit voltage of the organic photovoltaic device when irradiated with light having an AM1.5 spectrum is greater than about 1.0 V.

[0108] In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than 22%. In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than about 5%. In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than about 10%. In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than about 15%. In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than about 20%. In one embodiment, the power conversion efficiency of the device when irradiated with light is greater than about 25%.

[0109] In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than 22%. In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than about 5%. In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than about 10%. In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than about 15%. In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than about 20%. In one embodiment, the power conversion efficiency of the device when irradiated with light having an AM1.5 spectrum is greater than about 25%.

[0110] In one embodiment, the external quantum efficiency of the electroluminescence (EL) of the organic photovoltaic device is ≥5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥7.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥10%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥12.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥15%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥17.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥20%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥22.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥25%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥27.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥30%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥32.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥35%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥37.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥40%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥42.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥45%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥47.5%. In one embodiment, the external quantum efficiency of the EL of the organic photovoltaic device is ≥50%.

[0111] In one embodiment, the organic photovoltaic device is a tandem photovoltaic device. In one embodiment, the organic photovoltaic device is a tandem photovoltaic device comprising at least two sub-cell units. In one embodiment, the organic photovoltaic device is a tandem photovoltaic device comprising at least two sub-cell units, wherein at least one sub-cell unit is an organic substance, and at least one sub-cell unit is an organic substance, perovskite or CdTe. In one embodiment, the sub-cell units are monolithically integrated. In one embodiment, at least one sub-cell unit comprises a conductive material. In one embodiment, at least one sub-cell unit comprises perovskite. In one embodiment, at least one sub-cell unit comprises cadmium telluride (CdTe). In one embodiment, at least one sub-cell unit comprises a metal.

[0112] In one embodiment, the present invention relates to an organic photovoltaic device comprising: an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of general formula (I):

[0113]

[0114] Wherein:

[0115] D is a donor; and

[0116] A 1 and A 2 are each independently an acceptor;

[0117] wherein the energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) is less than about 200 meV.

[0118] In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is at least 0.1. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is less than 0.1. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is about 0.2. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is about 0.3. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is about 0.4. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is about 0.5. In one embodiment, the oscillator strength for the transition from the ground state and the lowest energy excited state is greater than 0.1.

[0119] In one embodiment, the HOMO / LUMO overlap of the compound is greater than 10%. In one embodiment, the HOMO / LUMO overlap of the compound is greater than about 5%. In one embodiment, the HOMO / LUMO overlap of the compound is greater than about 10%. In one embodiment, the HOMO / LUMO overlap of the compound is greater than 15%.

[0120] In one embodiment, the organic photovoltaic device further comprises a compound having one of the following general formulas:

[0121]

[0122]

[0123] wherein

[0124] Ar 1 and Ar 2 are each independently selected from C 5 -C 16 aryl and C 2 -C 16 heteroaryl; and

[0125] R a is an electron-withdrawing group.

[0126] In one embodiment, the present invention relates to an organic photovoltaic device comprising an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of general formula (I):

[0127]

[0128] Wherein:

[0129] D is a donor;

[0130] A 1 and A 2 are each independently a compound capable of thermally activated delayed fluorescence (TADF); and

[0131] A 1 and A 2 are each covalently bonded to D.

[0132] In one embodiment, the present invention further relates to an organic photovoltaic device comprising: an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of general formula (I):

[0133]

[0134] Wherein:

[0135] D is a donor;

[0136] A 1 and A 2 are each independently an acceptor; and

[0137] D is a compound capable of thermally activated delayed fluorescence (TADF).

[0138] In one embodiment, the present invention further relates to an organic photovoltaic device comprising: an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of general formula (I):

[0139]

[0140] Wherein:

[0141] D is a donor;

[0142] A 1 and A 2 are each independently an acceptor; and

[0143] The oscillator strength for the transition from the ground state and the lowest energy excited state is at least 0.1.

[0144] In one embodiment, the present invention further relates to an organic photovoltaic device comprising: an anode; a cathode; at least one anode buffer or at least one cathode buffer; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of general formula (I):

[0145]

[0146] Wherein:

[0147] D is a donor;

[0148] A 1 and A 2 are each independently an acceptor; and

[0149] The energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) is less than about 200 meV.

[0150] In one embodiment, the OPV device comprises a single-junction organic photovoltaic device. In one embodiment, the OPV device comprises two electrodes having an anode and a cathode in a stacked relationship, at least one donor composition and at least one acceptor composition, wherein a donor-acceptor material or an active layer is positioned between the two electrodes. In one embodiment, one or more intermediate layers may be positioned between the anode and the active layer. Additionally or alternatively, one or more intermediate layers may be positioned between the active layer and the cathode.

[0151] In one embodiment, the anode comprises a conductive oxide, a thin metal layer, or a conductive polymer. In one embodiment, the anode comprises a conductive metal oxide. Exemplary conductive metal oxides include, but are not limited to, indium tin oxide (ITO), tin oxide (TO), gallium indium tin oxide (GITO), zinc oxide (ZO), and zinc indium tin oxide (ZITO). In one embodiment, the anode comprises a metal layer. Exemplary metals for the metal layer include, but are not limited to, Ag, Au, Pd, Pt, Ti, V, Zn, Sn, Al, Co, Ni, Cu, Cr, and combinations thereof. In one embodiment, the metal layer comprises a thin metal layer. In one embodiment, anode 102 comprises a conductive polymer. Exemplary conductive polymers include, but are not limited to, polyaniline (PANI) or 3,4-polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS). In one embodiment, the thickness of the anode ranges from about 0.1 - 100 nm. In one embodiment, the thickness of the anode ranges from about 1 - 10 nm. In one embodiment, the thickness of the anode ranges from about 0.1 - 10 nm. In one embodiment, the thickness of the anode ranges from about 10 - 100 nm. In one embodiment, the anode comprises a light-transmissive or semi-light-transmissive conductive material.

[0152] In one embodiment, the cathode comprises a conductive oxide, a metal layer, or a conductive polymer. Exemplary conductive oxides, metal layers, and conductive polymers are described elsewhere herein. In one embodiment, the cathode comprises a thin metal layer. In one embodiment, the cathode comprises a metal or a metal alloy. In one embodiment, the cathode may comprise Ca, Al, Mg, Ti, W, Ag, Au, or another suitable metal or an alloy thereof. In one embodiment, the thickness of the cathode ranges from about 0.1 - 100 nm. In one embodiment, the thickness of the cathode ranges from about 1 - 10 nm. In one embodiment, the thickness of the cathode ranges from about 0.1 - 10 nm. In one embodiment, the thickness of the cathode ranges from about 10 - 100 nm. In one embodiment, the cathode comprises a light-transmissive or semi-light-transmissive conductive material.

[0153] In one embodiment, the OPV device may comprise one or more charge collection / transport intermediate layers positioned between the electrodes and the active region or layer. In one embodiment, the OPV device comprises one or more intermediate layers. In one embodiment, the intermediate layer comprises a metal oxide. Exemplary metal oxides include, but are not limited to, MoO 3 、MoO x 、V 2 O 5 、ZnO, and TiO 2 。In one embodiment, the first intermediate layer has the same composition as the second intermediate layer. In one embodiment, the first intermediate layer and the second intermediate layer have different compositions. In one embodiment, the thickness of the intermediate layers independently ranges from about 0.1 - 100 nm. In one embodiment, the thickness of the intermediate layers independently ranges from about 1 - 10 nm. In one embodiment, the thickness of the intermediate layers independently ranges from about 0.1 - 10 nm. In one embodiment, the thickness of the intermediate layers independently ranges from about 10 - 100 nm.

[0154] In one embodiment, the OPV device comprises the respective layers of a tandem or multi-junction photovoltaic device. In one embodiment, the OPV device comprises two electrodes having an anode and a cathode in a stacked relationship, at least one donor composition, and at least one acceptor composition, the at least one donor composition and the at least one acceptor composition being positioned within a plurality of active layers or regions located between the two electrodes. Other active layers or regions are possible. In one embodiment, the anode and the cathode each independently comprise a conductive oxide, a thin metal layer, or a conductive polymer. Exemplary conductive oxides, metal layers, and conductive polymers are described elsewhere herein.

[0155] In one embodiment, the OPV device includes one or more intermediate layers positioned between the anode and the first active layer. Additionally or alternatively, at least one intermediate layer may be positioned between the second active layer and the cathode. In one embodiment, the OPV device includes one or more intermediate layers positioned between the first active layer and the second active layer. In one embodiment, the OPV device includes a first intermediate layer. In one embodiment, the OPV device includes a second intermediate layer. In one embodiment, the OPV device includes a third intermediate layer. In one embodiment, the OPV device includes both the first intermediate layer and the second intermediate layer. In one embodiment, the OPV device includes both the first intermediate layer and the third intermediate layer. In one embodiment, the OPV device includes both the second intermediate layer and the third intermediate layer. In one embodiment, the OPV device includes the first intermediate layer, the second intermediate layer, and the third intermediate layer. In one embodiment, the first intermediate layer, the second intermediate layer, and / or the third intermediate layer includes a metal oxide. Exemplary metal oxides are described elsewhere herein.

[0156] Compound

[0157] In one embodiment, the present invention further relates to a compound represented by the general formula (I):

[0158]

[0159] Wherein:

[0160] D is a donor; and

[0161] A 1 and A 2 are each independently an acceptor; and

[0162] The energy difference (ΔE 1 ) between the triplet state (T 1 ) and the singlet state (S ST ) is less than about 200 meV.

[0163] In one embodiment, D includes a group represented by a formula selected from the group consisting of formula (D-1) to formula (D-5):

[0164]

[0165] Wherein

[0166] The dashed line represents a direct bond to A 1 and A 2 ;

[0167] M is a monovalent, divalent, trivalent, or tetravalent atom;

[0168] Each R 1 to R4 Independently represents mono-permissible substitution to maximum-permissible substitution;

[0169] Each R 1 through R 4 Independently represents hydrogen or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;

[0170] Any two adjacent Rs 1 through R 4 Optionally are connected or fused together to form an optionally substituted ring;

[0171] Each X 1 through X 4 Independently represents CR or N;

[0172] Each X 5 through X 7 Independently represents CR 2 , NR, O, or S; and

[0173] Each R is independently an electron-donating group, hydrogen, or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

[0174] In one embodiment, D comprises a structure selected from the group consisting of:

[0175]

[0176] wherein

[0177] R is selected from the group consisting of: an electron-donating group, hydrogen, or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; and

[0178] Each Rd is independently an electron-donating group.

[0179] In one embodiment, D comprises a structure represented by formula (D-6):

[0180]

[0181] wherein

[0182] the dashed line represents a direct bond to A 1 and A 2 ;

[0183] each X 1 to X 4 independently represents O, S, NR, and CR 2 ;

[0184] R 1 represents mono-permissible substitution to maximum-permissible substitution;

[0185] each R is independently hydrogen or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; and

[0186] R 1 is independently selected, at each occurrence, from the group consisting of: an electron-donating group, hydrogen, or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

[0187] In one embodiment, D is represented by a structure selected from the group consisting of:

[0188]

[0189] wherein

[0190] Each R independently represents hydrogen or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;

[0191] Each R d independently represents an electron-donating group; and

[0192] The dashed line represents a direct bond to A 1 and A 2 is a direct bond.

[0193] In one embodiment, R d is selected from the group consisting of: C 5 -C 16 aryl, C 2 -C 16 heteroaryl, C 5 -C 20 alkoxy, and NR 2 .

[0194] In one embodiment, A 1 and A 2 each independently contain a group represented by a formula selected from the group consisting of formula (A-1) to formula (A-7):

[0195]

[0196]

[0197] wherein

[0198] the dashed line represents a direct bond to D;

[0199] Each R 1 to R 6 independently represents single allowable substitution to maximum allowable substitution;

[0200] Each R 1 to R 6 independently represents hydrogen or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof;

[0201] Any two adjacent Rs 1 to R 6 are optionally linked or fused together to form an optionally substituted ring;

[0202] Each X 1 to X 9 independently represents CR or N; and

[0203] each R is independently an electron-withdrawing group, hydrogen, or a substituent selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

[0204] In one embodiment, A 1 and A 2 each independently is selected from the group consisting of

[0205]

[0206]

[0207] wherein

[0208] the dashed line represents a direct bond to D;

[0209] each R is independently selected from the group consisting of: hydrogen or a substituent selected from the group consisting of: deuterium, C 1 -C 20 alkyl, C 1 -C 20 heteroalkyl, C 5 -C 16 aryl, C 2 -C 16 heteroaryl, C 5 -C 16 cycloalkyl;

[0210] each R a is independently an electron-withdrawing group; and

[0211] any two adjacent Rs or Rs a may optionally be linked to form a ring.

[0212] In one embodiment, R is C 4 -C 20 alkyl, C 3 -C 20 heteroalkyl, C 5 -C16 Aryl, C 2 -C 16 heteroaryl, or C 5 -C 16 cycloalkyl.

[0213] In one embodiment, the dihedral angle between the best least-squares plane of the D group and the least-squares plane of A 1 or A 2 is greater than about 30°. In one embodiment, the dihedral angle is from 10° to 90°. In one embodiment, the dihedral angle is from 10° to 80°. In one embodiment, the dihedral angle is from 10° to 70°. In one embodiment, the dihedral angle is from 10° to 60°. In one embodiment, the dihedral angle is from 10° to 90°. In one embodiment, the dihedral angle is from 10° to 50°. In one embodiment, the dihedral angle is from 10° to 40°. In one embodiment, the dihedral angle is from 20° to 90°. In one embodiment, the dihedral angle is from 20° to 80°. In one embodiment, the dihedral angle is from 20° to 70°. In one embodiment, the dihedral angle is from 20° to 60°. In one embodiment, the dihedral angle is from 20° to 90°. In one embodiment, the dihedral angle is from 20° to 50°. In one embodiment, the dihedral angle is from 20° to 40°.

[0214] Compounds having the general formula II are also described:

[0215]

[0216] wherein:

[0217] M is a metal having a charge of +2;

[0218] D1 and D2 are independently hydrogen or substituents selected from the group consisting of:

[0219]

[0220] Each Y is independently selected from the group consisting of:

[0221]

[0222] Ar 1 is an aromatic group fused to an adjacent ring and is selected from the group consisting of:

[0223] and

[0224] Each X, M 1 、M 2 、M 3 、M 4, R and R' are independently hydrogen or substituents selected from the group consisting of: deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, thioalkyl, boranyl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino and combinations thereof;

[0225] provided that M 1 , M 2 , M 3 and M 4 at least one of them represents halogen.

[0226] In one embodiment, each R independently represents alkyl, alkenyl or a combination thereof. In one embodiment, each R independently represents C 1 -C 20 alkyl, which optionally contains one or more internal alkenyl groups. In one embodiment, each R independently represents aryl, which is further substituted by alkyl, alkenyl or a combination thereof. In one embodiment, each R independently represents aryl substituted by C 1 -C 20 alkyl.

[0227] In one embodiment, the compound of formula II is represented by the following compound:

[0228]

[0229] In one embodiment, the compound is represented by formula III:

[0230]

[0231] wherein Don and Don' are each independently represented by formula A or formula B:

[0232]

[0233] wherein in formula A and formula B:

[0234] * represents a bond to Acc;

[0235] # represents a bond to Z or Z';

[0236] Each X is independently selected from the group consisting of: O, S, Se, Te, GeRR', CRR', SiRR' and NR.

[0237] Each Y is independently selected from the group consisting of N and CR”;

[0238] R 1 、R2 、R, R', and R” independently represent hydrogen or a substituent selected from the group consisting of: deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkylene, sulfinyl, sulfonyl, phosphino, and combinations thereof; and any two adjacent substituents, said any two adjacent substituents optionally being linked to form a ring;

[0239] Acc is a divalent electron-withdrawing group;

[0240] Z and Z' each together are respectively the donor groups D and D' or are respectively the acceptor groups A and A';

[0241] wherein each of Acc, Z, and Z' can be further substituted by one or more substituents selected from the group consisting of: deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkylene, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0242] wherein any two adjacent substituents are optionally linked to form a ring.

[0243] In one embodiment, Acc is an electron-withdrawing group selected from the group consisting of: SO 2 、CF 2 、imine, ketone, polycyclic aromatic compound, polycyclic heteroaromatic compound, alkyl-boric acid, aryl-boric acid, alkoxy-boric acid, and combinations thereof;

[0244] In one embodiment, D and D' are independently selected from the group consisting of: alkoxy, aryloxy, heteroaryloxy, alkenyloxy, alkyloxy, allyloxy, amino, dialkylamino, diarylamino, thioalkyl, thioaryl, thioheteroaryl, and combinations thereof; and

[0245] In one embodiment, A and A' are independently selected from the group consisting of: halogen, NO 2 、CN, SO 2 R、CF 3 、imine, ketone, aldehyde, polycyclic aromatic compound, polycyclic heteroaromatic compound, alkyl-boric acid, aryl-boric acid, alkoxy-boric acid, and combinations thereof; and

[0246] In one embodiment, each of Acc, Z, and Z' may be further substituted by one or more substituents selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkylene, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein any two adjacent substituents are optionally linked to form a ring.

[0247] In one embodiment, the compound is represented by Formula IV:

[0248]

[0249] wherein in Formula IV,

[0250] Acc is a divalent electron-withdrawing group selected from the group consisting of polycyclic aromatic compounds, polycyclic heteroaromatic compounds, arylboronic acids, alkoxyboronic acids, and combinations thereof;

[0251] Each X is independently selected from the group consisting of O, S, Se, Te, GeRR', CRR', SiRR', and NR;

[0252] Each Y is independently selected from the group consisting of N and CR”;

[0253] Z and Z' together are each a donor group D and D' or each an acceptor group A and A';

[0254] D and D' are independently selected from the group consisting of alkoxy, aryloxy, heteroaryloxy, alkenyloxy, alkyloxy, allyloxy, amino, dialkylamino, diarylamino, thioalkyl, thioaryl, thioheteroaryl, and combinations thereof;

[0255] A and A' are independently selected from the group consisting of halogen, NO 2 2 3

[0256] R 1 1 2 2 ​​​​​​', R, R' and R” independently represent hydrogen or a substituent selected from the group consisting of: deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkyl, sulfinyl, sulfonyl, phosphino and combinations thereof; and

[0257] Any two adjacent substituents are optionally linked to form a ring.

[0258] In one embodiment, R 1 and R 2 At least one of which is represented by one of the following structures:

[0259]

[0260] In one embodiment, Acc is represented by one of the following structures:

[0261]

[0262]

[0263] Where the wavy line represents the bond to Don and Don';

[0264] Where each X independently represents O, S, Se, NR 5 or C(CN) 2 ;

[0265] Where Y and Z independently represent CR 4 and N;

[0266] Where represents an optional aryl, heteroaryl, polyaromatic or polyheteroaryl ring fusion;

[0267] Where R 3 , R 4 , R 5 and R 6 independently represent hydrogen or a substituent selected from the group consisting of: deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkyl, sulfinyl, sulfonyl, phosphino and combinations thereof;

[0268] Where each R 7 is independently an electron-withdrawing group selected from the group consisting of: halogen, haloalkyl, aryl, heteroaryl, nitrile and combinations thereof; and

[0269] Any two adjacent substituents are optionally linked to form a ring.

[0270] In one embodiment, Z and Z' are independently represented by one of the following structures:

[0271]

[0272] wherein each X independently represents O, S, Se, NR C or C(CN) 2 ;

[0273] R A , R B , R C and R D are independently hydrogen or a substituent selected from the group consisting of: deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, thioalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, cyano, isocyano, thioalkylene, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0274] Any two adjacent substituents are optionally linked to form a ring.

[0275] In one embodiment, Z and Z' are each a receptor group selected from the group consisting of:

[0276]

[0277]

[0278] In one embodiment, Z and Z' are each a donor group selected from the group consisting of:

[0279]

[0280] In one embodiment, Acc is selected from the group consisting of:

[0281]

[0282] In one embodiment, the compound is represented by one of the following structures:

[0283]

[0284] wherein in formula C:

[0285] X is F, CF 3 , CN, SO 3 H or SO 2 Me; and

[0286] Y is NH2 , NMe 2 , NPh 2 , N(4-OMePh) 2 , N(3,4,5-(OMe)Ph) 2 or N(2,4,6-(OMe)Ph) 2 ;

[0287]

[0288]

[0289]

[0290] Experimental Examples

[0291] Example 1: Factors Controlling Thermally Activated Delayed Fluorescence (TADF) in Organic Photovoltaics

[0292] One of the most significant challenges currently facing humanity and our planet is how to slow down or prevent the rate at which climate change occurs due to carbon dioxide emissions. The increasing energy demand and its adverse environmental impacts make it urgent to develop large-scale deployment of renewable energy technologies, especially solar energy. Inorganic photovoltaics have developed rapidly and currently dominate the solar market. Compared with the toxic materials and high-temperature processes involved in making inorganic semiconductors from materials such as silicon and gallium arsenide, organic materials are inexpensive and use very little energy in their production compared to inorganic electronic materials. Organic materials are generally environmentally benign and easy to handle, and they can be deposited on almost any surface. In particular, the performance of organic photovoltaic (OPV) devices has been greatly improved in the past few decades, with the power conversion efficiency (PCE) now approaching 20% (Fu, J. et al. Nat. Commun. 14, 1760 (2023)). This is due to the emergence of non-fullerene electron acceptors (NFAs), which have largely replaced the more conventional fullerene acceptors. Compared with fullerenes, non-fullerenes offer a variety of benefits, including significantly higher absorption rates and greater synthetic tuning for specific matching with donors, as well as their typical planar structures that usually enable improved electron mobility (Li, Y. et al. Nat. Rev. Mater. 8, 186–201 (2023)).

[0293] One of the most critical factors that still needs to be addressed in order for organic photovoltaics to be competitive on the world stage is the non-radiative decay back to the ground state. Within the context of OPVs, non-radiative decay generally refers to the relaxation of the interfacial donor / acceptor charge transfer state back to the ground state in the absence of photon emission, thereby losing potential energy in the form of heat. Even with the introduction of highly efficient non-fullerene acceptors pushing efficiencies close to 20%, non-radiative decay remains the dominant loss mechanism.

[0294] Triplet states are typically formed during OPV cell operation by bimolecular recombination of free carriers (Gillett, AJ et al. Nature 597, 666–671 (2021)). 1 The state is usually one of the lowest energy states in the system, i.e., its formation and subsequent relaxation back to the ground state requires nonradiative voltage losses from charge transfer 3 The reverse transition of the CT state back to the triplet state becomes more feasible, which provides another pathway for non-radiative decay loss. Figure 3 As shown, ΔE in NFA S-T It is usually large, around 0.4 eV. However, reducing this exchange energy has the potential advantage of allowing triplet recycling via reverse intersystem crossing (RISC). S-T It is also necessary for thermally activated delayed fluorescence (TADF), a key strategy for enhancing the efficiency of organic light-emitting diodes (OLEDs). Therefore, the same orbital decoupling strategy employed in the field of TADF-OLEDs is also applicable to OPVs.

[0295] This article discloses a series of ΔE S-T Reduced NFA materials, which is the key to enhancing reverse intersystem crossing. In certain embodiments, the non-fullerene acceptor composition is a compound having the following structure:

[0296]

[0297] in:

[0298] D1 and / or D2 are selected from the group consisting of:

[0299]

[0300] R is a straight or branched saturated or unsaturated non-aromatic hydrocarbon (e.g. 0 -C 20 within the scope);

[0301] Y is selected from the group consisting of:

[0302]

[0303] Ar 1 is an aromatic group that is conjugated, fused, or linked to an adjacent ring and is selected from the group consisting of:

[0304]

[0305] M 1 -M 4 is independently selected from the group consisting of hydrogen, fluorine, chlorine, bromine, iodine, and cyano, where at least one of the 1 -M 6 is a halogen;

[0306] X is selected from the group consisting of chlorine, fluorine, and hydrogen.

[0307] An example of the target molecule is depicted below:

[0308]

[0309] Calculations with compounds of this class reveal that ΔE ST is very small. The calculations were done using B3LYP / LACVP; the results are the same as those with LANL2DZ.

[0310]

[0311]

[0312] Donor HOMO (eV) LUMO (eV) <![CDATA[S 1 (eV)|f]]> <![CDATA[T 1 (eV)]]> <![CDATA[ΔE ST (eV)]]> <![CDATA[S n (eV)|f]]> TPA -5.11 -4.03 0.88|0.19 0.70 0.18 1.37|2.36 PTZ -5.24 -4.13 0.88|0 0.86 0.02 1.39|2.38 <![CDATA[PTZ CN > -5.24 -4.09 0.92|0 0.86 0.06 1.48|1.61

[0313] Example 2: TADF Materials for High - Performance Organic Photovoltaics

[0314] OPV has become a subject of intense interest due to its steadily improving efficiency and potentially lower cost compared to conventional binary cell units. A single-junction cell achieved a power conversion efficiency of PCE = 19.4%, which is only surpassed by a tandem cell containing two binary sub-cell units. Despite its relatively high efficiency, OPV has two distinct drawbacks. The first is that the efficiency is still far lower than that of inorganic solar cell units made from crystalline silicon (c-Si), CIGS, GaAs, and perovskite. This is mainly because the energy loss E loss = E opt – V OC of OPV is approximately 20% higher than that of its competing technologies, as Figure 4 shown. Here, the open-circuit voltage is V OC , and the photon energy is E opt . The solid line represents radiative V OClimit, which defines the Shockley-Queisser (SQ) limit as PCE = 31%. Interestingly, although Y6 has achieved a record-high single-junction cell efficiency, its E loss is comparable to that of all high-performance NFAs. The reasons for the losses caused by various technologies are evident from the data in Table 1. Compared with competing technologies, the V loss loss of the non-radiative component (DV OC ) in OPV is much larger. This is reflected in the extremely low external quantum efficiency of OPV electroluminescence of EQE OC,nr = 0.01% obtained by forward biasing PV, compared with 35.7% for the highest-performance GaAs system. (Note that Kirchoff's law requires that a perfect absorber is also a perfect emitter). EL

[0315] Table 1: Loss comparison of several PV technologies

[0316] Material PCE (%) <![CDATA[E g -qV OC (V)]]> <![CDATA[ΔV OC,nr > <![CDATA[EQE EL (%)]]> c - Si 26.7 0.36 0.107 1.6 GaAs 29.1 0.31 0.027 35.7 Perovskite 25.6 0.34 0.059 10.1 Organic 19.2 0.56 0.240 0.01

[0317] The main reason for the low efficiency in OPV is Figure 3 the excessive energy loss during the photo-generation process shown in (Li et al. Nature Reviews: Materials 8, 186–201 (2023)). The formation of charge-transfer (CT) states at the D-A interface leads to non-radiative energy loss (ΔE 2 ) during Frenkel exciton dissociation. The "hot" CT state can transfer to the charge-separation (CS) state in an endothermic manner, which ultimately generates free charge pairs. However, in this scenario, there is also a high chance that the CS state can recombine non-pairwise back to the CT state. Spin statistics show that the probability of singlet (i.e., radiative) 1 CT formation upon electron-hole encounter is 1 / 4, while the probability of forming a triplet 3 CT state is 3 / 4. The triplet CT state does not couple to the ground state in principle, but can convert to a local triplet T 1 , and the local triplet then decays non-radiatively, resulting in a further significant energy loss ΔE 3 accompanied by a decrease in V OC .

[0318] Narrowing the singlet-triplet exchange energy gap ΔE ST is crucial for eliminating non-radiative losses. Materials are described herein that enable the T 1 state to be close to the relevant S 1 state and also have an energy higher than the CT state. Thus, to the T 1 ​The reverse transfer of the state rapidly refills the radiative S 1 state, resulting in ΔE 3 →0. This strategy narrows the efficiency gap between OPV and other thin-film solar cell unit technologies. Therefore, the present disclosure describes the design of a new generation of OPV materials with relatively low cost molecules having an unusually low exchange energy while meeting other limitations required for active OPV materials.

[0319] The donor material D and acceptor material A developed herein are designed such that their lowest energy excited state becomes an intramolecular charge transfer state ICT. To avoid confusion between the intramolecular charge transfer (ICT) excited state and CT that ultimately leads to free charges, the symbols a and d are used to represent the intramolecular acceptor and donor groups, and A and D are used to represent the acceptor material and donor material containing a heterojunction in the OPV. Thus, the non-fullerene acceptor NFA will be represented as ada, and the excited ICT state of NFA is a 1 / 2- d + a 1 / 2- (Luo et al., Journal of Materials Chemistry A (J. Mater. Chem. A), 2022, 10, 3255 - 3295; Yan et al., Nature Reviews: Materials 3, 18003 (2018); Zhou et al., Nano Energy 103A, 107802 (2022)). The excited A or D generates a charge transfer state CT, thereby forming an exciplex at the interface of the two materials, i.e., [A - D + . This exciplex CT has singlet and triplet spin configurations, but it is almost degenerate because the hole and electron are on separate molecules.

[0320] When designing active materials for OPV, many parameters need to be considered: (1) The combination of A and D materials needs to efficiently absorb solar radiation from ultraviolet light to NIR (up to 1.2 eV in the program), (2) D / A needs to generate a heterojunction that efficiently forms a CT state (D*A → [A - D + or DA* → [A - D +), (3) The material must form a nano-phase separated film that efficiently transports carriers to the collection electrode (Schlenker and Thompson; Chem. Commun., 2011, 47, 3702-3716; Hedley et al., Chem. Rev. 2017, 117, 2, 796–837; Solak and Irmak, RSC Adv., 2023, 13, 12244-12269). In some cases, an additional requirement is that the NIR absorber must have a small ΔE ST (<0.10 eV).

[0321] Achieving a very small ΔE ST values have been demonstrated in both organic compounds and organometallic compounds, where the main applications of the organic compounds and the organometallic compounds are organic LEDs (Muthiah Ravinson and Thompson, Mater. Horiz., 2020, 7, 1210-1217; Shi et al., Chem. Sci., 2022, 13, 3625-3651; Im et al., Chem. Mater. 2017, 29, 5, 1946–1963; Xiao et al., Chem. Sci., 2022, 13, 8906-8923). In OLEDs, carrier recombination generates both singlet and triplet excited states. A small ΔE ST allows triplets to thermally populate singlets and emit through thermally activated delayed fluorescence TADF. These TADF-based OLEDs have high EL efficiency, which is also the goal for OPV here. The ΔE ST values of TADF-based emitters are reported to be in the range of 10-30 meV, much lower than the goal here. Although TADF emitters seem to meet the requirements of OPV materials, they have two key drawbacks: in some cases, the reported TADF emitters do not absorb significantly in the visible to NIR region, and more importantly, their absorption rates are typically <10 3 cm -1 . A small ΔE ST is achieved by restricting the overlap degree of the hole wave function and the electron wave function in the ICT state, thereby minimizing the exchange energy and thus reducing ΔE STIt is achieved by using a structure that twists the a and d groups of the compound into an almost orthogonal configuration. This limits the exchange energy but also limits the oscillator strength, and it has been found that these two parameters are related (Li et al., Journal of Materials Chemistry C (J. Mater. Chem. C), 2022, 10, 4674 - 4683; Muniz et al., Journal of the American Chemical Society (J. Am. Chem. Soc.) 2022, 144, 39, 17916–17928). The commonly bonded ada NFA compounds in current OPVs use separate a and d groups to form an ICT excited state a 1 / 2- d + a 1 / 2- , thus minimizing the exciton binding energy, but the a and d groups are effectively conjugated, resulting in a high ΔE ST and a high molar absorption rate. The molecules described herein produce a low ΔE ST without sacrificing the absorption rate excessively and meet all other requirements of the above-mentioned active OPV materials; while maintaining α≥10 4 cm -1 , the compound achieves ΔE ST <100 meV.

[0322] The discovery work of these materials began with the theoretical modeling of various materials. Previously, DFT and TDDFT modeling were used to accurately predict the S 1 and T 1 energies and the frontier orbital energies of TADF materials; the same method is applied here to identify the best candidates for synthesis and research in the laboratory. The initial material discovery work aimed to find new acceptor (A) compounds with a small ΔE ST . In RAMP and OPV studies, these acceptors are coupled with the confirmed polymer donors. The compounds studied have structures that utilize the following design criteria:

[0323] Use simple structures and modular designs of a and d to reduce manufacturing costs. Examples of the a and d groups to be explored in this procedure are shown below. These compounds have a certain range of LUMO (for a) and HOMO (for d) energies and are readily available. Pairing different a and d groups will allow tuning of the ICT absorption energy in the visible light spectrum and into the NIR region. Conventional NFA cores and simplified donor cores were explored. It is predicted that the simplified cores shown have donor properties similar to those of the "ordinary" cores but can be prepared from low-cost starting materials in only a few synthetic steps, which makes the cost of NFA with these cores significantly lower than the cost of previously reported NFA. The high cost of previously reported NFA makes these panels impractical for real-world applications. These materials are incorporated into full-size panels.

[0324] Adjust the LUMO energy and HOMO energy of a and d to produce visible - NIR absorption. A series of materials were prepared with different a - groups and d - groups. The modeling work provided a good estimate of the absorption energy and oscillator strength (f) for each ada structure or dad structure. The modeling study also provided a good estimate of the ΔE ST value for each candidate material. The study began with optimized structures, but also explored structures where the a - group and d - group were mostly in - plane (conjugated) and structures where the groups were twisted out of the plane. It was expected that the in - plane version could produce the highest ΔE ST and f, while the twisted version could have lower values of ΔE ST and f, with a minimum when a and d were at 90° to each other.

[0325] Coupling chemistry controls / minimizes the d - a overlap degree. It was important to control the degree of overlap between the a - group and the d - group. Too much overlap and ΔE ST would be too high, too little overlap and f would be too low. The initial approach was to find the a / d pair that produced the correct absorption energy and study ΔE ST and f as a function of the twist angle between a and d. Computational constraints could be used to control the angle between the a - group and the d - group, but in the complexes prepared, steric interactions of peripheral alkyl groups were used to impose a given twist angle. These steric interactions could also be well - modeled computationally.

[0326] The second method of controlling the a / d overlap was to couple them through poorly - conjugated bonds. These bonds included acetylene (-C≡C-) groups and meta - substituted aromatic rings. These bonds led to inefficient conjugation between the groups they coupled (Korovina et al., Journal of the American Chemical Society 2018, 140, 32, 10179–10190; Korovina et al., Journal of the American Chemical Society 2016, 138, 2, 617–627). The steric approach could be used in conjunction with meta - substituted aromatic rings, but the acetylene linker would limit the steric interaction between a and d.

[0327] These studies yielded 10 - 15 candidate materials with low ΔE ST and high f, which were prepared such that their physical properties could be measured. The materials were studied by RAMP and tested in OPV structures.

[0328] d and / or a groups with strong visible light absorption. To achieve maximum efficiency, all photons in the spectrum that enter the NIR must be utilized. For absorption through the spectrum, OPVs typically have three or more active materials. An alternative is to construct a units and d units with multiple chromophores that transfer energy to a final excited state. A similar approach is used in Nature, in which antenna chromophores funnel energy into a special charge-separating pair. In the materials studied herein, the use of a and d groups that are themselves good chromophores and coupling them to an a / d system will be investigated. Examples of chromophoric a and d groups are shown below. In the blue-to-green portion of the spectrum, all of these groups have high molar absorptivities ε = 10 4 -10 5 M -1 cm -1 . If the group is the portion of the ada system tuned to have ICT absorption in the NIR, any light absorbed by the chromophore unit will decay rapidly and efficiently to the ICT state. Multiple candidate structures for this internal energy transfer function have been explored in ada and dad architectures.

[0329] Donor

[0330] Simplified donor core of ada NFA: 3 - 4 steps from inexpensive starting materials:

[0331]

[0332] (R = alkyl, aryl, thiophene; R d = thiophene, Ph, OR, NR 2 ):

[0333] Donor core used in common NFA: 10 - 12 steps from expensive starting materials.

[0334]

[0335] Chromophore donor core for higher-energy sensitized ada NFA;

[0336]

[0337] (a = CN, NO 2 , CH = C(CN) 2 , SO 3 R; R = alkyl, aryl, thiophene);

[0338] Note that the IC group has minimum solubility in solution processing devices.

[0339] High - PCE material development : low V OCis a key limiting factor for the reported PCE values for OPV. The low triplet energy of the active material severely limits its radiative efficiency and thereby limits Voc by recapturing charge-separated excitons into non-radiative triplets oc (see Introduction section). A solution to this problem is to develop materials with a small energy gap between S 1 and T 1 to allow for thermal filling of S 1 starting from T 1 , while raising the energy of T 1 above the charge-transfer (CT) state at the donor (D)-acceptor (A) junction to prevent back transfer to the triplet state( Figure 3 ). Density functional theory (DFT) is used to accurately predict the S 1 , T 1 and frontier orbital energies of OLED materials; these same methods are applied to identify optimal candidates for the synthesis of high-efficiency OPV D and A molecules that minimize the S-T exchange energy ΔE ST to reduce non-radiative triplet losses (see Figure 3 ).

[0340] Simple structures of electron - withdrawing subunit (a) and electron - donating subunit (d) and modular designs for cost reduction. Pairing different a-groups with d-groups (as in the claimed compounds) can tune the absorption energy in the visible light and into the NIR spectral region. Conventional NFA molecular cores and simplified donor cores are utilized. The simplified cores shown have donor properties similar to those of the “ordinary” NFA cores and can reduce costs by a factor of 5 or more based on reagents and reduced synthetic complexity.

[0341] Tune the frontier orbital energies of a and d molecular subsets for visible - NIR absorption. Modeling efforts provide estimates of the absorption energy i.e. the oscillator strength (f) and ΔE ST for each a-d-a (A) or d-a-d (D) structure. Both planar and twisted molecular motifs will be explored. Completely planar molecules yield the highest ΔE ST and f (thus significant non-radiative losses but high absorption), while twisted structures yield smaller values of ΔE ST and f, which are minimized when a and d are orthogonal.

[0342] Coupling chemistry will control the d - a overlap degree. It is important to control the degree of overlap between the a-group and the d-group, as too much overlap increases ΔE ST , while small overlap decreases f. Identifying specific a / d pairs for which ΔE ST and f are functions of the twist angle between a and d has led to a situation where ΔE ST < 0.1 eV while maintaining a high f, thus giving an absorption coefficient > 10 4 cm-1 Candidate structures. The steric interactions of the peripheral alkyl groups are utilized to impose a given twist angle using modeling to identify the optimal substitution pattern prior to synthesis.

[0343] An ultrathin and self-assembled structure (IC-SAM and C 70 )( Figure 5 ) inserted between the active layer and the transport layer of the OPV eliminates the chemically destructive reaction with the thiophene-containing NFA, resulting in an extrapolated lifetime of 30 years or more for laboratory cell units. Similar modeling and buffering methods are performed to determine whether these long-term reliability results apply to high-efficiency small ΔE 3 molecules. Thus, a new family of interfacial buffer layers was prepared, which is illustrated by way of example in ST . For the n-type metal oxide buffer, a self-assembled monolayer functionalized with an electron-withdrawing group is used, while a triarylamine group is attached to the hydroxyl anchor to protect the active region at the p-oxide interface. These simple molecules are synthesized or purchased from commercial suppliers (if available). Figure 6 Importantly, the sun-facing surface of the substrate is coated with 600 nm ZnO to prevent high-energy photochemical damage to the active layer. The coating acts as a UV filter with a cut-off value just below 400 nm and exhibits almost 100% transmittance at wavelengths extending into the near-infrared.

[0344] Cells and modules are subjected to accelerated lifetime testing (ALT). An example of a population of NFA-based OPVs tested at U-M at several different visible light intensities is shown in

[0345] , which gives an extrapolated lifetime of 30 years at 1 sun intensity. ALT can test a population of up to 40 actively cooled devices simultaneously using ultra-high-intensity LED arena lighting. High-intensity UV LEDs are used to apply UV exposure separately, but as described above, the solution-deposited ZnO UV filter layer is highly effective in preventing short-wavelength damage to cell materials. There is a significant research gap between ALT and the predicted lifetime in field deployment. Figure 7 Manufacturing tandem OPV cells is very simple. In most respects, as

[0346] Low - cost and efficient semi - transparent (st) OPV and multi - junction cell unit development: Figure 8 ​Stacking the battery cells vertically is as simple and straightforward as manufacturing single-junction battery cells - a feature unique to organic thin-film devices. Additionally, integrating OPV with other material-based sub-battery cells is equally simple because the lamination process occurs at very low temperatures and there are no lattice compatibility issues (such as lattice matching, material interdiffusion) with other layers in the multi-junction. Also, while semi-transparency is the key to unlocking the multi-purpose solar potential of billions of m 2 Many of the tools used in the optical coatings designed for st-OPV are also applicable to tandem designs, which is crucial for the influential multi-purpose solar potential. Organic multi-junction battery cells using extremely high-efficiency sub-battery cells are another approach and mitigation strategy to achieve a PCE of 25%. Additionally, long-wavelength absorbing OPV sub-battery cells can be combined with perovskite or CdTe-based battery cells to further enhance their efficiency.

[0347] The tandem battery cell employs highly transparent and efficient Ag nanoparticles or ZnO charge recombination regions, which are buffered by hole and electron conducting and organic buffer layers that connect the upper and lower elements in series. Figure 8 An example of a 15% efficient OPV / OPV tandem battery cell is shown, which includes a top NFA-based battery cell connected to a bottom vapor-deposited short-wavelength battery cell, and the top NFA-based battery cell and the bottom vapor-deposited short-wavelength battery cell are interconnected with a buffer Ag nanoparticle layer. Figure 9 The results of an optical model for designing the battery cell structure are shown. Note the total transmittance of the interconnect layer. The performance results of the tandem battery cell constructed according to this design are also shown ( Figure 10 ). Similar processes and modeling as used in Figures 8 - 10 are applied to even higher-efficiency battery cells developed in the work plan disclosed herein.

[0348] Determine V oc The three mechanisms for determining the magnitude of are: (i) radiative recombination of optically generated excited states or excitons within the donor or acceptor regions; (ii) radiative recombination due to CT state relaxation; and (iii) non-radiative recombination due to defect states or other diode non-ideal factors. Over time, the subsequent processes may lead to voltage losses. To quantify these effects, the non-radiative voltage loss ΔV nr is defined as the difference between the open-circuit voltage (radiative limit) in the presence of only radiative processes and the actual V oc of the battery cell, i.e.:

[0349]

[0350] Here, J sc is the short-circuit current density, is the dark saturation current density at the radiative limit (i.e., in the absence of non-radiative effects, it is the lower limit of the experimental value J 0 ), k is the Boltzmann constant, T is the temperature, and q is the elementary charge. The detailed balance theory requires that under equilibrium, i.e., open-circuit conditions, the photocurrent be balanced by equal and opposite injection currents, so that the total current within the device is zero. Previously, detailed balance has been invoked to relate ΔV nr to the external emission efficiency under forward bias. Other work has incorrectly assumed that the external emission efficiency is equal to the external quantum efficiency of EL η EL , and has asserted that within the radiative limit, η EL = 1. However, for organic devices where emission is dominated by CT states, when the emission CT state efficiency η CT is unified, the current generated by non-radiative recombination will be exactly zero, and the emission CT state efficiency is not equivalent to η EL = 1. For organic materials, CT state emission is confined to the donor / acceptor junction, whereby η CT can only account for non-radiative defect sites occurring within the active region. Instead, the measured EL efficiency is given by:

[0351] η EL =γχ em η CT , (2)

[0352] where γ is the charge balance factor (i.e., the ratio of the photons emitted to the electrons that recombine radiatively with holes at the HJ). The ratio χ em of the emission CT states formed by electrical injection depends on whether the states reside in the singlet manifold or the triplet manifold. That is, if the CT state is singlet and the triplet is non-emissive, then χ em = 0.25. Alternatively, if the CT state is an emissive triplet or a mixed state, then χ em can be assumed to have a value up to 1. Therefore, η EL must account for χ em , and γ must be considered when determining the magnitude of η CT .

[0353] Under open-circuit conditions, the ideal diode equation for an OPV is written as:

[0354]

[0355] where n is the ideality factor (explicitly defined only for pure diffusion n = 1 current and mid-gap recombination n = 2 current), k PPd is for V ocThe dissociation rate of polaron pairs, k, under PPd,eq is the dissociation rate of polaron pairs at thermal equilibrium, and J ph is the photocurrent. An OPV at thermal equilibrium needs to balance the photocurrent generated by thermal excitation through current injection, so as to recombine in the CT state. Therefore, in the dark:

[0356]

[0357] where is the saturation current generated by the excitation caused by room-temperature blackbody, and J out is the radiative recombination current density generated by the CT state. For simplicity, it is assumed that in Equation 4, k PPd ≈k PPd,eq . Returning to η EL , which is defined as the number of photons emitted per injected electron:

[0358]

[0359] where J inj is the injected current density generated by the applied forward voltage. Equation 2 provides a physical understanding of the reason for the efficiency of organic light-emitting diodes (OLEDs), while Equation 5 is defined in terms of measurable quantities from an OPV cell unit that operates as an OLED.

[0360] At open circuit, J inj (V oc ) must be balanced by an equal and opposite photocurrent, i.e., J inj (V oc ) = J ph (V oc ); this is the equation that allows η EL to be related to V oc . For an OPV, it cannot be assumed that J ph (V oc ) = J sc , because J ph depends on the voltage. This occurs because in an ideal junction, k PPd depends on the electric field at the heterojunction. Thus,

[0361] J inj (V oc ) = J ph (V oc ) = J sc -J Δ (6)

[0362] where J Δ takes into account J ph (V oc ) and Jsc The difference between

[0363] Therefore, η EL The higher, the lower the loss in the open-circuit voltage. For an OPV device that wants η EL to approach a nearly uniform and highly efficient one, thus in the present disclosure, materials with η EL greater than 5%, greater than 10%, greater than 20%, and greater than 50% are designed.

[0364] Example 2: Small singlet-triplet gap materials based on dipyrrole derivatives

[0365] Initial studies of small singlet-triplet gap (low ΔE ST ) materials began by examining porphyrins. Porphyrins are of interest because they are naturally occurring molecules with a high molar absorptivity (>10 5 M -1 cm -1 ) and the ability to absorb low-energy light due to their planar π-conjugated core. The rigid structure of this core presents an additional ability to control the placement of additional components (in this case donors and acceptors), which will allow modification of the structural and electronic properties of the molecule. One such property that can be controlled will be the singlet energy and triplet energy, which will then affect the absorption and emission properties of the material.

[0366] Searching for synthetically simpler candidates with many of the same properties as porphyrins, the structure was truncated to a dipyrrole structure (the dipyrrole structure is roughly similar to half of porphyrin, Figure 11 ). This dipyrrole motif is the backbone of a class of molecules called boron dipyrromethene (BODIPY), and these molecules are strongly absorptive, allow rigid positioning of components, and are simple and easy to generate synthetically.

[0367] A series of donor groups and acceptor groups are shown below, but a wide range of donor groups and acceptor groups can be used to tune the excited-state energy and singlet-triplet gap.

[0368]

[0369] Table 1: Screened BODIPY structures and singlet energy, triplet energy, and ΔE ST . The singlet, triplet, and energy differences are provided in electron volts (eV).

[0370] Entry <![CDATA[R 1 > <![CDATA[R 2 > <![CDATA[R 3 > <![CDATA[R 4 > <![CDATA[R 5 > <![CDATA[R 6 > <![CDATA[R 7 > <![CDATA[S 1 > <![CDATA[T 1 > <![CDATA[ΔE ST > 1 Me H Me H Me H Me 3.031 1.461 1.570 2 BTD Me Me H Me Me H 2.017 1.063 0.953 3 BTD Me Me H Me Me BTD 1.577 0.845 0.733 4 BTD Me Me pPTZ Me Me H 1.460 1.061 0.399 5 BTD Me Me pPTZ Me Me BTD 1.169 0.860 0.309 6 Me BTD Me H Me H Me 2.085 1.276 0.809 7 Me BTD Me H Me BTD Me 1.923 1.270 0.654 8 Me BTD Me pPTZ Me H Me 1.573 1.282 0.291 9 Me BTD Me pPTZ Me BTD Me 1.349 1.282 0.067 10 Me BTD - CHO Me pPTZ Me BTD - CHO Me 1.604 1.456 0.149 11 Me BTD - CN Me pPTZ Me BTD - CN Me 1.572 1.448 0.124 12 Me pPTZ Me BTD Me pPTZ Me 0.736 0.735 0.001 13 Me ePTZ Me pBTD Me ePTZ Me 1.248 1.244 0.004 14 Me H Me JUL Me H Me 2.35 1.55 0.807 15 Me BTD Me JUL Me BTD Me 1.66 1.27 0.394 16 H BTD H JUL H BTD H 1.94 1.30 0.634 17 Me H Me mJUL Me H Me 2.16 1.56 0.600 18 Me BTD Me mJUL Me BTD Me 1.36 1.27 0.087 19 H BTD H mJUL H BTD H 1.33 1.21 0.113

[0371] Based on previous studies using compound Y6 ( Figure 12 ), further studies were conducted using the BODIPY scaffold.

[0372]

[0373] This D–BODIPY–A core has the following desired characteristics: large molar absorptivity (of the core); ideal positioning of D and A; direct / modular synthesis; and predicted small ΔE S-T 。

[0374] Possible variations are:

[0375]

[0376] The following exemplary compounds were identified:

[0377]

[0378]

[0379] It should be 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 replaced with other materials and structures without departing from the spirit of the invention. Accordingly, the claimed invention may include variations from the specific examples and preferred embodiments described herein, as will be apparent to those skilled in the art. It should be understood that the various theories as to why the invention works are not intended to be limiting.

Claims

1. An organic photovoltaic device, comprising: anode; a cathode; and a photoactive organic material in a layer disposed between the anode and the cathode; in: The energy difference (ΔE) between the triplet energy state (T1) and the singlet energy state (S1) in the photoactive organic material ST ) is less than about 300 meV; and When the organic photovoltaic device is illuminated by light having an AM1.5 spectrum, the open circuit voltage of the organic photovoltaic device is greater than 0.9 V, the power conversion efficiency is greater than 22%, and the EL external quantum efficiency is greater than 5%.

2. The organic photovoltaic device according to claim 1, The photoactive organic material comprises a compound of general formula (I): in: D is the donor; and A 1 and A 2 Each is independently a receptor. The organic photovoltaic device according to claim 2 , wherein the HOMO / LUMO overlap of the compound is greater than 10%.

4. The organic photovoltaic device according to claim 2, wherein the organic photovoltaic device further comprises a compound comprising one of the following general formulas: in Ar 1 and Ar 2 Each independently selected from C5-C 16 Aryl and C2-C 16 heteroaryl; and R a It is an electron withdrawing group.

5. The organic photovoltaic device according to claim 1, wherein the photoactive organic material comprises a compound of formula (I): in: D is the donor; A 1 and A 2 are each independently a compound capable of thermally activated delayed fluorescence (TADF); and A 1 and A 2 Each is covalently bound to D.

6. The organic photovoltaic device according to claim 1, wherein the photoactive organic material comprises a compound of formula (I): in: D is the donor; A 1 and A 2 each independently a receptor; and D is a compound capable of thermally activated delayed fluorescence TADF.

7. The organic photovoltaic device according to claim 1, wherein the photoactive organic material comprises a compound of formula (I): in: D is the donor; A 1 and A 2 each independently a receptor; and The oscillator strength for transitions from the ground state and the lowest energy excited state is at least 0.

1.

8. The organic photovoltaic device according to claim 1, wherein the photoactive organic material comprises a compound of formula (I): in: D is the donor; A 1 and A 2 each independently a receptor; and The energy difference (ΔE) between the triplet state (T1) and the singlet state (S1) ST ) is less than about 200meV.

9. The organic photovoltaic device according to claim 1, wherein the photoactive organic material comprises a compound represented by general formula (I): in: D is the donor; and A 1 and A 2 each independently a receptor; and The energy difference (ΔE) between the triplet state (T1) and the singlet state (S1) ST ) is less than about 100meV.

10. The organic photovoltaic device according to claim 9, wherein D comprises a group represented by a formula selected from the group consisting of formula (D-1) to formula (D-5): in The dotted line indicates the 1 and A 2 Direct key for M is a monovalent, divalent, trivalent or tetravalent atom; Each R 1 To R 4 independently represents a single permissible substitution up to the maximum permissible substitution; Each R 1 To R 4 independently represent hydrogen or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; Any two adjacent R 1 To R 4 are optionally linked or fused together to form an optionally substituted ring; Each X 1 To X 4 independently represents CR or N; Each X 5 To X 7 independently represents CR2, NR, O or S; and Each R is independently an electron donating group, hydrogen, or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

11. The organic photovoltaic device according to claim 9, wherein D comprises a structure selected from the group consisting of: in R is selected from the group consisting of an electron donating group, hydrogen, or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; and Each R d are independently electron donating groups.

12. The organic photovoltaic device according to claim 9, wherein D comprises a structure represented by formula (D-6): in The dotted line indicates the 1 and A 2 Direct key for Each X 1 To X 4 O, S, NR, and CR2 are represented independently; R 1 Indicates single permissible substitution to maximum permissible substitution; each R is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; and R 1 and independently at each occurrence selected from the group consisting of an electron donating group, hydrogen, or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

13. The organic photovoltaic device according to claim 9, wherein D is represented by a structure selected from the group consisting of: in each R independently represents hydrogen or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; Each R d independently represent electron donating groups; and The dotted line indicates the 1 and A 2 Direct key.

14. The organic photovoltaic device according to claim 9, wherein A 1 and A 2 Each independently comprises a group represented by a formula selected from the group consisting of formula (A-1) to formula (A-7): in The dashed line indicates the direct bond to D; Each R 1 To R 6 independently represents a single permissible substitution up to the maximum permissible substitution; Each R 1 To R 6 independently represent hydrogen or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof; Any two adjacent R 1 To R 6 are optionally linked or fused together to form an optionally substituted ring; Each X 1 To X 9 independently represents CR or N; and Each R is independently an electron withdrawing group, hydrogen, or a substituent selected from the group consisting of deuterium, halogen, pseudohalogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, amide, hydroxy, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, acyl, carboxylic acid, benzoyl, ether, ester, vinyl, ketone, sulfinyl, sulfonyl, cyano, phosphino, and combinations thereof.

15. The organic photovoltaic device according to claim 9, wherein the optimal least square plane of the D group is 1 or A 2 The dihedral angle between the least squares planes is greater than about 30°.

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