Perovskite material and uses thereof

Abstract

The present invention relates to a hybrid material comprising a perovskite and a singlet fission compound. The hybrid material comprises layers of the perovskite in which the singlet fission compound occupies an interlayer space of the perovskite structure. The hybrid material may be useful as a semiconductor, e.g., in a photovoltaic cell. Also disclosed are processes for preparing the hybrid material and components comprising the hybrid material, such as a photovoltaic cell.

Description

PEROVSKITE MATERIAL AND USES THEREOFTECHNICAL FIELD

[0001] The present invention relates to a hybrid material comprising a perovskite and a singlet fission compound. Also disclosed is the use of the hybrid material, e.g., as a semiconductor in a photovoltaic cell, processes for preparing the hybrid material, and components comprising the hybrid material, such as a photovoltaic cell.BACKGROUND ART

[0002] For solar energy to make a significant contribution to meeting our current and future energy needs, a reduction in cost as well as an increase in efficiency is required. Increased efficiency in solar cells can be achieved by making full use of the solar spectrum via spectral management techniques that effectively split high energy photons into multiple photons and excitations. Most solar cells exhibit a single absorption threshold, with a single energy gap (Egbetween the valence and conduction bands. The sun’s broad emission spectrum spans the ultraviolet, visible, and infrared regions, leading to a variety of inherent loss mechanisms in the single threshold design. The two largest-loss channels are caused by the transmission of photons with energies lower than the bandgap of the cell and, to a greater extent, by the thermalisation of highly energetic charges that dissipate energy in excess of the bandgap as heat. As a result, single-threshold cells at a specific bandgap can only efficiently harvest a limited portion (~ 32%) of the solar spectrum and its energy. This is the Shockley-Queisser limit (SQL).

[0003] Singlet fission is an excitation multiplication process in organic molecules, where the initially photogenerated singlet exciton (Si) breaks up to form two free triplets (Ti). Therefore, each absorbed photon produces two electron-hole pairs. Triplet energy transfer has been demonstrated in hybrid materials such as pentacene / lead selenide quantum dots, and tetracene / lead sulfide quantum dots. The issue with both systems is that photovoltaic devices that utilize lead chalcogenide quantum dot semiconductors are inferior compared to those that utilize silicon and other upcoming technologies. Experiments have investigated coupling tetracene to silicon. However, triplet-energy-transfer (TET) between these two compounds is hindered owing to poor electronic coupling between the organic tetracene and inorganic silicon. Interlayers such as hafnium oxide / nitride can increase the efficiency of triplet energy transfer, but still not to acceptable levels.

[0004] An emerging technology is perovskite photovoltaics, which are devices that utilize lead and or tin halide perovskites as their absorbing semiconductor. The first such device was a perovskite sensitized cell with a power conversion efficiency (PCE) of 3.8%, reported in 2009 by Kojima et al.1Since then, Perovskite photovoltaic technologies have rapidly developed and have achieved PCEs of 25.6%.2The reason for this success lies in the fact that metal halide perovskites are excellent semiconductors despite being solution processable, and only require annealing temperatures of 100 °C / 212 °F to 150 °C / 302°F to form. An issue with metal halide perovskites, however, is their instability in ambient conditions owing to their ionic nature.

[0005] Two examples of energy transfer from a singlet fission material to a perovskite have been reported. Both studies show electron transfer to the perovskite from the triplet pair (TTi) state of singlet fission molecules.3,4However, to get any benefit from singlet fission requires energy transfer from individual triplets (Ti), not the TTi state. A third study tried to observe TET from the triplet state of tetracene to a low band gap lead / tin perovskite.5No TET was observed and, via computational analysis, it was concluded that TET does not occur because the perovskite and tetracene do not form a good interface.

[0006] Accordingly, it is an object of the present invention to go some way to avoiding the above disadvantages; and / or to at least provide the public with a useful choice.

[0007] Other objects of the invention may become apparent from the following description which is given by way of example only.

[0008] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date.SUMMARY OF THE INVENTION

[0009] In a first aspect, the present invention provides a hybrid material comprising a perovskite and a singlet fission compound, wherein the perovskite is layered and the singlet fission compound occupies an interlayer space of the perovskite.

[0010] In some embodiments, the hybrid material has the formula UyAn-iBnX3n+i, wherein U is the singlet fission compound, A is a cation, B is a metal cation, X is an anion, n is the numberof perovskite layers and y is 1 or 2. In some embodiments, the hybrid material has the formula U2BX4. In some embodiments, the hybrid material has the formula U2An-iBnX3n+i. In some embodiments, the hybrid material has the formula UAn-iBnX3n+i. In some embodiments, the hybrid material has the formula UBX4.

[0011] In some embodiments, the hybrid material has the formula UABX4.

[0012] In some embodiments, U is selected from the group consisting of an acene, a triene, a tetraene, a benzofuran, a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene, a rubrene, an azaacene, a thienoacene, a fulvene, a Cibalackrot-type compound and a combination of any two or more thereof. In some embodiments, U is selected from the group consisting of an acene, a benzofuran, a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene, and a combination of any two or more thereof. In some embodiments, the acene is pentacene, tetracene, anthracene or hexacene. In some embodiments, the triene is a hexatriene, e.g. a disubstituted hexatriene, e.g. a 1 ,6-disubstituted hextriene such as diphenylhexatriene (DPH). In some embodiments, the tetraene is an octatetraene, e.g. a disubstituted diphenyloctatetraene, e.g. a 1,8-disubstituted diphenyloctatetraene such as diphenyloctatetraene. In some embodiments, the benzofuran is a disubstituted benzofuran such as 1,3-diphenylisobenzofuran. In some embodiments, the rylene is perylene, terrylene or a diimide derivative thereof. In some embodiments, U is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene, diphenyloctatetraene, tetracene, pentacene and derivatives thereof. In some embodiments, U is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene, diphenyloctatetraene, tetracene and pentacene.

[0013] In some embodiments, the singlet fission compound comprises a cationic moiety. In some embodiments, the cationic moiety is an ammonium, a pyridinium or an amidinium. In some embodiments, the cationic moiety is an alkylammonium or ammonio-alkyl amide.

[0014] In some embodiments, U is selected from the group consisting of an acene (such as pentacene, tetracene, anthracene or hexacene), a triene (e.g. a disubstituted hexatriene such as diphenylhexatriene), a tetraene (e.g. a disubstituted octatetraene such as diphenyloctatetraene), a benzofuran (such as 1,3-diphenylisobenzofuran), a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene (such as perylene, terrylene or a diimide derivative thereof), a rubrene, an azaacene, a thienoacene, a fulvene, a Cibalackrot-type compound and a combination of any two or more thereof; wherein U comprises two cationic moieties independently selected from thegroup consisting of an ammonium, a pyridinium or an amidinium. In some embodiments, U is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene, diphenyloctatetraene, tetracene, pentacene and derivatives thereof; wherein U comprises two cationic moieties independently selected from the group consisting of an ammonium, a pyridinium or an amidinium.

[0015] In some embodiments, U is selected from the group consisting of an acene (such as pentacene, tetracene, anthracene or hexacene), a triene (such as diphenylhexatriene), a tetraene (such as diphenyloctatetraene), a benzofuran (such as 1,3-diphenylisobenzofuran), a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene (such as perylene, terrylene or a diimide derivative thereof), a rubrene, an azaacene, a thienoacene, a fulvene, a Cibalackrot-type compound and a combination of any two or more thereof; wherein U comprises two cationic moieties independently selected from the group consisting of an ammonium, a pyridinium or an amidinium; wherein the cationic moiety is attached directly to U or attached by a linker selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, carboxyl, amide and a combination of any two or more thereof. In some embodiments, U is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene, diphenyloctatetraene, tetracene, pentacene and derivatives thereof; wherein U comprises two cationic moieties independently selected from the group consisting of an ammonium, a pyridinium or an amidinium; wherein the cationic moiety is attached directly to U or attached by a linker selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, carboxyl, amide and a combination of any two or more thereof.

[0016] In some embodiments, U is 2,2'-(((lE,3E,5E)-hexa-l,3,5-triene-l,6-diyl)bis(4,l- phenylene))bis(ethan-l-aminium) (DPHEA) or N-(2-ammonioethyl)-tetracene-5-carboxylic acid amide (TCEA). In some embodiments, U is 2,2'-(((lE,3E,5E)-hexa-l,3,5-triene-l,6-diyl)bis(4,l- phenylene))bis(ethan-l-aminium) (DPHEA). In some embodiments, U is N-(2-ammonioethyl)- tetracene-5-carboxylic acid amide (TCEA).

[0017] In some embodiments, A is an organic cation or an inorganic cation. In some embodiments, A is selected from the group consisting of an ammonium, an amidinium, a hydrazinium, an imidazolium, a guanidinium, cesium ion (Cs+) and a combination of any two or more thereof. In some embodiments, A is selected from the group consisting of methylammonium (MA), formamidinium, Cs+and a combination of any two or more thereof.

[0018] In some embodiments, B is selected from the group consisting of Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Pd2+, Pt2+, Cu2+, Zn2+, Cd2+, Hg2+, Ge2+, Sn2+, Pb2+, Eu2+, Tm2+and Yb2+and a combination of any two or more thereof. In some embodiments, B is selected from the group consisting of Pb2+, Sn2+and combinations thereof.

[0019] In some embodiments, X is an inorganic anion, organic anion or a combination thereof. In some embodiments, the inorganic anion is a halide. In some embodiments, the organic anion is a thiocyanate or RCOO" wherein R is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl or aryl, each of which is optionally substituted. In some embodiments, R is Ci- loalkyl, C2-ioalkenyl, C2-ioalkynyl, Ca-iocycloalkyl, Ca-iocycloalkenyl or aryl, each of which is optionally substituted. In some embodiments, R is Ci-ealkyl, C2-6alkenyl, C2-6alkynyl, C3- ecycloalkyl, Cs ecycloalkenyl or aryl, each of which is optionally substituted. In some embodiments, R is unsubstituted Ci-ealkyl.

[0020] In some embodiments, U is DPHEA, A is MA, B is Sn2+o.5Pb2+o.5 and X is I". In some embodiments, U is TCEA, A is MA, B is Sn2+o.sPb2+o.5 and X is I-.

[0021] In some embodiments, the hybrid material further comprises a coating comprising a singlet fission compound and / or a chromophore. In some embodiments, the singlet fission compound in the coating is the same as the singlet fission compound in the interlayer space. In some embodiments, the singlet fission compound in the coating is different from the singlet fission compound in the interlayer space.

[0022] In some embodiments, the hybrid material is in the form of a thin film.

[0023] In another aspect, the present invention provides a process for preparing the hybrid material according to the first aspect, the process comprising: i. combining a precursor of the singlet fission compound, a precursor of the cation and a precursor of the metal cation in the presence of an anion in solution to form a precursor of the hybrid material; and ii. isolating the hybrid material from the solution.

[0024] In some embodiments, the hybrid material is isolated from the solution by removing the solvent. In some embodiments, isolating the hybrid material from the solution comprises a step selected from the group consisting of spin coating, drop casting, blade coating, printing,thermal evaporation and a combination of any two or more thereof. In some embodiments, the solution comprising the precursor of the hybrid material is spin-coated onto a substrate. In some embodiments, the solution comprising the precursor of the hybrid material is spin-coated onto a substrate to provide the hybrid material in the form of a thin film. In some embodiments, the solution comprising the precursor of the hybrid material is spin-coated onto a substrate, heated and annealed.

[0025] In some embodiments, the precursor of the singlet fission compound, the precursor of the cation and / or the precursor of the metal cation is provided as a salt. In some embodiments, the precursor of the singlet fission compound, the precursor of the cation and / or the precursor of the metal cation is provided as a halide salt.

[0026] In another aspect, the present invention relates to use of the hybrid material according to the first aspect as a semiconductor.

[0027] In another aspect, the present invention provides a photovoltaic cell comprising the hybrid material according to the first aspect.

[0028] In another aspect, the present invention provides a light emitting diode (LED) comprising the hybrid material according to the first aspect.

[0029] In another aspect, the present invention relates to use of the hybrid material according to the first aspect as a photocatalyst.

[0030] This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0031] In addition, where features or aspects of the invention are described in terms of Markush groups, those persons skilled in the art will appreciate that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0032] As used herein “(s)” following a noun means the plural and / or singular forms of the noun.

[0033] As used herein the term “and / or” means “and” or “or” or both.

[0034] The term “comprising” as used in this specification means “consisting at least in part of’. When interpreting each statement in this specification that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner.

[0035] The term “alkyl” as used herein refers to a straight or branched chain saturated aliphatic hydrocarbon group. For example, the alkyl group may be a Ci-ioalkyl group, i.e. an alkyl group having 1 to 10 carbon atoms. The Ci-ioalkyl group may be a straight chain or branched chain saturated aliphatic hydrocarbon group. In some embodiments, the alkyl group is a Ci-ealkyl. In some embodiments, the Ci-ealkyl group is a straight chain saturated aliphatic hydrocarbon group, such as methyl, ethyl, propyl, butyl or pentyl. In some embodiments, the Ci-ealkyl group is a branched chain saturated aliphatic hydrocarbon group, such as isopropyl or isobutyl.

[0036] The term “alkenyl” as used herein refers to a straight or branched chain unsaturated aliphatic hydrocarbon group having one or more carbon-carbon double bonds. For example, the alkenyl group may be a C2-ioalkenyl group, i.e. an alkenyl group having 2 to 10 carbon atoms. The C2 ioalkenyl group may be a straight chain or branched aliphatic hydrocarbon group. In some embodiments, the alkenyl group is a C2-6alkenyl. In some embodiments, the C2-6alkenyl group is a straight chain aliphatic hydrocarbon group, such as ethenyl, propenyl, butenyl or pentenyl. In some embodiments, the C2-6alkenyl group is a branched chain saturated aliphatic hydrocarbon group, such as isopropenyl or isobutenyl.

[0037] The term “alkynyl” as used herein refers to a straight or branched chain unsaturated aliphatic hydrocarbon group having one or more carbon-carbon triple bonds. For example, the alkynyl group may be a C2-ioalkynyl group, i.e. an alkynyl group having 2 to 10 carbon atoms. The C2 ioalkynyl group may be a straight chain or branched aliphatic hydrocarbon group. In some embodiments, the alkynyl group is a C2-6alkynyl. In some embodiments, the C2-6alkynyl group is a straight chain aliphatic hydrocarbon group, such as propynyl, butynyl or pentynyl. In some embodiments, the C2-6alkynyl group is a branched chain saturated aliphatic hydrocarbon group.

[0038] The term “cycloalkyl” as used herein refers to a cyclic saturated aliphatic hydrocarbon group. For example, the cycloalkyl group may be a Ca iocycloalkyl group, i.e. a cycloalkyl grouphaving 3 to 10 carbon atoms. In some embodiments, the cycloalkyl group is a Cs ecycloalkyl. In some embodiments, the Cs ecycloalkyl group is cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0039] The term “cycloalkenyl” as used herein refers to a cyclic unsaturated aliphatic hydrocarbon having one or more carbon-carbon double bonds. For example, the cycloalkenyl group may be a Cs iocycloalkenyl group, i.e. a cycloalkenyl group having 3 to 10 carbon atoms. In some embodiments, the cycloalkenyl group is a C3-6cycloalkenyl. In some embodiments, the C3-6cycloalkenyl group is cyclopropenyl, cyclobutenyl, cyclopentenyl or cyclohexenyl.

[0040] The term “aryl” as used herein refers to a monocyclic, bicyclic or tricyclic, carbon ring system, that includes fused rings, wherein at least one ring in the system is aromatic.

[0041] The term “substituted” as used herein refers to a group in which a hydrogen on one or more carbons of the hydrocarbon backbone has been replaced with a substituent. Such substituents can include, for example, aryl, halo, hydroxyl, alkoxyl, silyloxy, carbonyl, phosphoryl, amino, amidyl, iminyl, phenyl, thiol, thioalkyl, sulfonyl and nitro. It will be understood by those skilled in the art that other substituents known in the art may be used.

[0042] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0043] Although the present invention is broadly as defined above, those persons skilled in the art will appreciate that the invention is not limited thereto and that the invention also includes embodiments of which the following description gives examples.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The invention will now be described with reference to the Figures in which:

[0045] Figure 1 shows a hybrid material according to the present invention comprising a perovskite (n=5) and a singlet fission compound, 2,2'-(((lE,3E,5E)-hexa-l,3,5-triene-l,6- diyl)bis(4, 1 -phenylene))bis(ethan- 1 -aminium) (DPHEA)

[0046] Figure 2 shows a comparison of the triplet energy level of tetracene and the band gap of three perovskites: M ASnF, M APbF and MA(Sno.sPbo.5)l3.

[0047] Figure 3 shows a comparison of the triplet energy level of DPHEA and the band gap of three perovskites: M ASnF, M APbE and MA(Sno.5Pbo.5)l3-

[0048] Figure 4 is a graph of the absorbance and photoluminescence of DPHMAn-iSnnl3n+i at four different layer thicknesses (n=infinity, 20, 10 and 5).

[0049] Figure 5 is a graph of the photoluminescence quantum efficiency (PLQE) magnitude change at 450 nm and 637 nm for a tin-containing perovskite with tetracene, a tin-containing perovskite without tetracene, a lead-containing perovskite with tetracene and a lead-containing perovskite without tetracene.

[0050] Figure 6 is a graph of the photoluminescence quantum efficiency (PLQE) magnitude change at 450 nm and 637 nm for a hybrid material comprising DPHMAn-i(Sno.5Pbo.5)nl3n+i and a DPH layer (coating) at four different layer thicknesses (n= inf in i ty , 20, 10 and 5).DETAILED DESCRIPTION OF THE INVENTION

[0051] The present invention relates to a hybrid material comprising a perovskite and a singlet fission compound. The hybrid material comprises layers of the perovskite in which the singlet fission compound occupies the interlayer space of the perovskite structure. The hybrid material may be useful as a semiconductor, e.g., in a photovoltaic cell. Also disclosed are processes for preparing the hybrid material and components comprising the hybrid material, such as a photovoltaic cell.

[0052] The hybrid material may comprise a two dimensional perovskite or mixed dimensional perovskite. For example, the hybrid material may comprise perovskite in which n is less than about 100. In some embodiments, n is less than about 50, less than about 40, less than about 30, less than about 20 or less than about 10. In some embodiments, n is less than 30. In some embodiments, n is less than 10. In some embodiments, n is 1, 2, 3, 4 or 5. Advantageously, two-dimensional and mixed dimensional perovskites are typically more stable than three-dimensional perovskites.

[0053] The hybrid material may have the formula UyAn-iBnX3n+i, wherein U is the singlet fission compound, A is a cation, B is a metal cation, X is an anion, n is the number of perovskite layers and y is 1 or 2. In some embodiments, the hybrid material has the formula U2BX4. In some embodiments, the hybrid material comprises a Ruddleson-Popper perovskite. In these embodiments, the hybrid material may have the formula U2An-iBnX3n+i. In some embodiments, the hybrid material comprises a Dion-Jacobson perovskite. In these embodiments, the hybrid material may have the formula UAn-iBnX3n+i. In some embodiments, the hybrid material has the formula UBX4.

[0054] The singlet fission compound (U) is a compound capable of undergoing singlet fission, i.e. a process in which an excited singlet (Si) is converted into two excited triplets (Ti). Various singlet fission compounds known in the art may be suitable for use in the hybrid material. Those persons skilled in the art may select a suitable singlet fission compound based on the material requirements of the application. Suitable singlet fission compounds may include an acene such as tetracene, pentacene, anthracene or hexacene; a triene, e.g. a disubstituted hexatriene, e.g. a 1,6- disubstituted hextriene such as diphenylhexatriene; a tetraene, e.g. a disubstituted octatetrene, e.g. a 1,8-disubstituted octatetrene such as diphenyloctatetraene; a benzofuran such as 1,3-diphenylisobenzofuran; a carotenoid; a diketopyrrolopyrrole; a fluorene; a rylene, such as perylene, terrylene or a diimide derivative thereof; a rubrene; an azaacene; a thienoacene; a fulvene; a Cibalackrot-type compound and a combination of any two or more thereof. Preferably, the singlet fission compound is selected from the group consisting of a benzofuran, a hexatriene, an octatetraene, or an acene. More preferably, the singlet fission compound is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene (DPH), diphenyloctatetraene, tetracene, pentacene and derivatives thereof.

[0055] Preferably, the singlet fission compound (U) comprises a cationic moiety. In some embodiments, the singlet fission compound (U) comprises two cationic moieties. Without wishing to be bound by theory, it is believed the cationic moiety is incorporated into the perovskite structure such that it at least partially replaces a cation in an interlayer of the structure, e.g., the cationic moiety replaces an ‘A’ cation in a conventional A2BX4 perovskite structure.

[0056] Suitable cationic moieties include, but are not limited to, an ammonium, a pyridinium or an amidinium. The ammonium may be attached directly to the core of the singlet fission compound or attached by a linker, e.g., a linker selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, carboxyl, amide and a combination of any two or more thereof. The linker may be substituted or unsubstituted. In some embodiments, the linker is selected from the group consisting of Ci-ioalkyl, C2-ioalkenyl, C2-ioalkynyl, Ca iocycloalkyl, C3- locycloalkenyl, Ci-ioalkyl amide, C2-ioalkenyl amide, C2-ioalkynyl amide, Cs-iocycloalkyl amide, C i-iocycloalkcnyl amide, Ci-ioalkyl carboxyl, C2-ioalkenyl carboxyl, C2-ioalkynyl carboxyl, C3- locycloalkyl carboxyl, Cs-iocycloalkenyl carboxyl, aryl, aryl amide or aryl carboxyl, each of which is optionally substituted. In some embodiments, the linker is selected from the group consisting of Ci-ealkyl, Cs ealkenyl, Cs ealkynyl, Cs ecycloalkyl, Cs ecycloalkenyl, Ci-ealkyl amide, Cs ealkenyl amide, Cs ealkynyl amide, Cs ecycloalkyl amide, Cs ecycloalkenyl amide, Ci- ealkyl carboxyl, Cs ealkenyl carboxyl, Cs ealkynyl carboxyl, Cs ecycloalkyl carboxyl, Csecycloalkenyl carboxyl, aryl, aryl amide or aryl carboxyl, each of which is optionally substituted. In some embodiments, the linker is Ci-ealkyl or Ci-ealkyl amide. Accordingly, in some embodiments, the cationic moiety is an alkylammonium such as 2-ethylammonium. In some embodiments, the alkylammonium is an Ci-ioalkylammonium. In some embodiments, the alkylammonium is a Ci-ealkylammonium, e.g., methylammonium, ethylammonium, propylammonium, butylammonium or pentylammonium. In some embodiments, the amide is an ammonio-Ci-ioalkyl amide. In some embodiments, the amide is a ammonio-Ci-ealkyl amide, e.g., ammonio-methyl amide, ammonio-ethyl amide, ammonio-propyl amide, ammonio-butyl amide or ammonio-pentyl amide. For example, in some embodiments, the singlet fission compound comprising a cationic moiety is 2,2'-(((lE,3E,5E)-hexa-l,3,5-triene-l,6-diyl)bis(4,l- phenylene))bis(ethan-l-aminium) (DPHEA) or N-(2-ammonioethyl)-tetracene-5-carboxylic acid amide (TCEA).

[0057] The singlet fission compound (U) may be a singlet fission compound known in the art modified to include a cationic moiety. A suitable attachment point for the cationic moiety will depend on the chemical structure of the singlet fission compound. Various attachment points may be suitable for a particular singlet fission compound.

[0058] The cation (A), metal cation (B) and anion (X) may be conventional materials used in perovskite materials. For example, the cation (A) may be an organic cation or an inorganic cation. In some embodiments, the inorganic cation is an alkali metal ion. In some embodiments, the cation is selected from the group consisting of an ammonium, such as an alkylammonium oracetylammonium, an amidinium such as formamidinium (FA), a hydrazinium, an imidazolium, a guanidinium, cesium ion (Cs+) and a combination of any two or more thereof. Suitable alkylammonium cations include, but are not limited to, methylammonium (MA), dimethylammonium, trimethylammonium, ethylammonium, propylammonium and butylammonium.

[0059] The metal cation may be selected from the group consisting of an alkaline earth metal such as Be2+, Mg2+, Ca2+, Sr2+and Ba2+; a transition metal such as Mn2+, Fe2+, Co2+, Ni2+, Pd2+, Pt2+, Cu2+, Zn2+, Cd2+and Hg2+; a post-transition metal or a metalloid such as Ge2+, Sn2+, Th2+, Pb2+, Bi2+; and a lanthanide such as Eu2+, Tm2+and Yb2+and a combination of any two or more thereof. Those persons skilled in the art will appreciate that other oxidation states may be useful depending on the form of the perovskite. For example, double perovskites may comprise metal cations in a 1+, 3+ or 4+ oxidation state. In some embodiments, the metal cation is selected from the group consisting of Pb2+, Sn2+and combinations thereof.

[0060] The anion (X) may be an inorganic anion or organic anion. In some embodiments, the anion is selected from the group consisting of a halide, such as F", Cl", Br", or T, an organic anion, such as a thiocyanate or RCOO" wherein R is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl or aryl, each of which is optionally substituted.

[0061] In some embodiments, the hybrid material has the formula UyAn-iBnX3n+i, wherein U is DPHEA, A is MA, B is Sn2+o.5Pb2+o.5 and X is T. In some embodiments, the hybrid material has the formula DPHEAMAn-i(Sno.5Pbo.5)nl3n+i. In some embodiments, the hybrid material has the formula UyAn-iBnX3n+i, wherein U is TCEA, A is MA, B is Sn2+o.sPb2+o.5 and X is T. In some embodiments, the hybrid material has the formula TCEA2MAn-i(Sno,5Pbo.5)nl3n+i.

[0062] The triplet energy level of the singlet fission compound is matched to the band gap of the perovskite. The energy levels of the two components may be matched by two measures.First, the relative energy difference between the fermi level (HOMO) and Ti level of the singlet fission compound may be matched with the relative energy difference between the valence band maximum (VBM) and the conduction band minimum (CBM) of the perovskite material.Preferably, the Ti energy is greater than the bandgap of the perovskite. Second, the absolute energy level positions of the triplet energy level of the singlet fission compound (i.e. the fermi level (HOMO) and Ti level) and the band gap of the perovskite (i.e. VBM and CBM) may be matched. Preferably, the absolute energy levels of the triplet energy and band gap are close butnot exactly the same. Without wishing to be bound by theory, it is believed a slight difference in absolute energy levels may drive the triplet transfer. Preferably, both the relative energy differences and the absolute energy level positions are matched. For example, Figure 2 depicts the triplet energy level of tetracene and the band gap of three perovskite materials: M ASnh, M APbh and MA(Sno.5Pbo.5)l3- In this example, the triplet energy level of tetracene is matched with the band gap of MA(Sno.sPbo.5)l3. In another example, Figure 3 depicts the triplet energy level of DPHEA and the band gap of three perovskite materials: MASnh, MAPbh and MA(Sno.sPbo.5)l3. In this example, the triplet energy level of DPHEA is matched with the band gap of MA(Sno.5Pbo.5)l3-

[0063] In some embodiments, the difference between the triplet energy level of the singlet fission compound and the band gap of the perovskite is less than about 0.5 eV. In some embodiments, the difference between the triplet energy level of the singlet fission compound and the band gap of the perovskite is less than about 0.4 eV, about 0.3 eV, about 0.2 eV or about 0.1 eV. In some embodiments, the difference between the triplet energy level of the singlet fission compound and the band gap of the perovskite is less than about 0.01 to about 0.3 eV. In some embodiments, the difference between the triplet energy level of the singlet fission compound and the band gap of the perovskite is less than about 0.01 to about 0.2 eV. In some embodiments, the difference between the triplet energy level of the singlet fission compound and the band gap of the perovskite is less than about 0.02 to about 0.15 eV.

[0064] The band gap of the perovskite may be tuned by modification of various elements of the material. For example, two-dimensional perovskites display wider band gaps than three- dimensional perovskites. Therefore, the band gap of the perovskite may be tuned by varying the thickness of the perovskite layers, i.e., increasing the thickness of the perovskite sheets narrows the band gap. Without wishing to be bound by theory, it is believed the perovskite layers act as quantum wells and, therefore, thicker layers produce narrower band gaps because of the wider quantum wells. Advantageously, controlling the band gap by varying the thickness of the perovskite sheets consequently tunes the absorbance and emission of the hybrid material. For example, Figure 4 shows the absorbance of a hybrid material at various layer thicknesses.

[0065] The band gap of the perovskite may also be modified by varying the chemical composition of the material. For example, in perovskites containing Sn2+and Pb2+, the band gap of the material may be tuned by varying the ratio of Sn2+to Pb2+, e.g. as shown in Figure 2.

[0066] The hybrid material may further comprise a coating comprising a singlet fission compound and / or a chromophore, i.e. a layer comprising a singlet fission compound and / or a chromophore, on a surface of the material. The singlet fission compound in the coating may be the same or different from the singlet fission compound in the interlayer space. The chromophore is a compound that absorbs light energy. The light energy absorbed by the chromophore may be transferred to the singlet fission material in the hybrid material, e.g. via Forster Resonance Energy Transfer (FRET). For this purpose, the chromophore preferably absorbs light at a higher energy level compared to the singlet fission compound. In some embodiments, the coating at least partially covers a surface of the hybrid material. In some embodiments, the coating substantially covers a surface of the hybrid material. Advantageously, the coating comprising a singlet fission compound and / or a chromophore may increase the amount of the light the hybrid material absorbs.

[0067] In some embodiments, the hybrid material is in the form of a thin film. The thin film may have a thickness of, e.g., about 50 to about 300 nm. In some embodiments, the thin film has a thickness of about 100 to about 250 nm. In some embodiments, the thin film has a thickness of about 200 nm.

[0068] The hybrid material may be prepared by providing a solution of a precursor of the singlet fission compound, a precursor of the cation and a precursor of the metal cation in the presence of an anion to form a precursor of the hybrid material. The hybrid material may then be isolated from the solution, e.g. by removing the solvent. In some embodiments, the hybrid material may be isolated by spin coating, drop casting, blade coating, printing, thermal evaporation or a combination of any two or more thereof. In some embodiments, the solution containing the precursor of the hybrid material is deposited on a substate, e.g. by spin-coating. Advantageously, conventional techniques for preparing perovskite materials may be utilised to prepare the hybrid material from a precursor of the singlet fission compound, a precursor of the cation and a precursor of the metal cation.

[0069] In some embodiments, the precursor of the singlet fission compound, the precursor of the cation and / or the precursor of the metal cation is provided as a salt. In some embodiments, the precursor of the singlet fission compound, the precursor of the cation and / or the precursor of the metal cation is provided as a salt with the anion, e.g., as a halide salt. For example, the hybrid material may be prepared by combining a halide salt of the singlet fission compound, a halide salt of the cation and a halide salt of the metal cation in solution. The halide salts may beindependently selected from the group consisting of a fluoride salt, a chloride salt, a bromide salt, an iodide salt and a combination of any two or more thereof. For example, the halide salt of the metal cation may comprise Snb and SnF2.

[0070] In some embodiments, the precursor of the metal cation comprises multiple metal cations, e.g., Pb2+and Sn2+. In those embodiments, the ratio of the metal cation precursors, e.g. the Pb halide salt and Sn halide salt, may be varied to achieve the desired ratio of each metal cation. Accordingly, in some embodiments, the ratio of Pb2+to Sn2+is about 0.99:0.01 to about 0.01:0.99. In some embodiments, the ratio of Pb2+to Sn2+is about 0.8:0.2 to about 0.2:0.8. In some embodiments, the ratio of Pb2+to Sn2+is about 0.7:0.3 to about 0.3:0.7. In some embodiments, the ratio of Pb2+to Sn2+is about 0.6:0.4 to about 0.4:0.6. In some embodiments, the ratio of Pb2+to Sn2+is about 0.5:0.5.

[0071] The hybrid material is useful as a semiconductor. For example, the hybrid material may be useful as a semiconductor in a photovoltaic cell or an LED. The hybrid material may also be useful as a photocatalyst.

[0072] The photovoltaic cell may be prepared according to conventional techniques known in the art. For example, the hybrid material may be spin-coated onto a suitable substrate.

[0073] The following non-limiting examples are provided to illustrate the present invention and in no way limit the scope thereof.EXAMPLESSynthesis of diphenylhexatriene, 2,2’-(((lE,3E,5E)-hexa-l,3,5-triene-l,6,diyl)bis(4,l,- phenylene))bis(ethan- 1 -aminium) iodide

[0074] 27.7 mg (0.087 mmol) of 2,2’-(((lE,3E,5E)-hexa-l,3,5-triene-l,6,diyl)bis(4,l,- phenylene))bis(ethan-l -amine) (DPHEA) was loaded into a round bottom flask. The flask was wrapped in aluminium foil to protect the precursor from light. The flask was purged with nitrogen at least three times. Into the flask, 1 mL of degassed chloroform was added. The flask was placed into an ultrasonic bath to dissolve the precursor, forming a clear yellow solution. Then, 34.5 L of 57 w.t. % hydroiodic acid (0.261 mmol, 3 mol eq) was added and the reaction mixture was sonicated for an hour at 25 °C. Immediately upon sonication, a very dark brown precipitate formed. The product was then dried under vacuum with gentle heating. A secondary cold trap was typically used because the product will sublimate, even at relatively high pressures, which will reduce the yield.Synthesis of S11I2

[0075] In a typical synthesis, 1200 mg of I2 (4.73 mmol) was placed into a 25 mL three-neck round bottom flask with a magnetic stir bar. To this flask, 10 mL of 2 mol L1hydrochloric acid was added. Dry nitrogen was bubbled through the solution to displace dissolved oxygen and place the flask under an inert atmosphere. Excess of 561 mg (>4.73 mmol) of tin metal pieces was added to flask. Excess metal was added to reduce the chance of SnL forming and to reduce Sn4+.

[0076] The reaction mixture was heated to reflux. After around 15 minutes, the dark brown colour of the solution turned yellow, and the solution was left to reflux for another 15 minutes to ensure all the iodine was consumed.

[0077] The warm solution was transferred to a Schlenk flask, where it was allowed to cool slowly to room temperature under N2 to slowly crystallise the product. Once at room temperature, the flask was placed in an ice bath to further crystallize the product. The supernatant was removed via syringe, and the product was heated to 100 °C under vacuum for at least an hour to remove both the remaining solvent, and any SnL that may have formed. Once the product was dry, the Schlenk flask was transferred to an N2 filled glove box, where the product could be weighed.Synthesis of DPHEAMAn-iSnnhn+i and DPHEAMAn-i(Sno.sPbo.s)nl3n+i thin films

[0078] In a glovebox (> 0.1 ppm O2, 0.1 ppm H2O), 186.3 mg (0.5 mmol) of SnL and 7.83 mg of SnF2 (0.05 mmol) was dissolved in 1 mL of a DMF / DMSO solution with a volume ratio of 4:1. To this solution, a small piece of tin metal (excess metal) was added to act as a reducing agent to consume any Sn4+. The vial was wrapped in aluminium foil and stirred overnight. In a separate vial, 230.7 mg (0.5 mmol) of PbL was dissolved in 1 mL of DMF / DMSO with a volume ratio of 4:1 and stirred overnight.

[0079] The following table displays the weights of methylammonium iodide (MAI) and DPHEAI2 (DPHEA) used for the four perovskite compositions.

[0080] The appropriate amounts of the iodide salts were weighed into four separate vials. The organic salts were dissolved into 280 pL of DMF:DMS0 solution with a volume ratio of 4:1, followed by the addition of either 220 pL of the Snb and SnF2 solution (for pure Sn compositions) or 110 pL of the SnF and SnF2 solution and 110 pL of the Pb I2 solution (for Sn and Pb compositions), resulting in 500 pL of a 0.22 mol L1solution. A small piece of tin metal (excess metal) was added to the solutions to act as a reducing agent.

[0081] The perovskite precursor solutions were stirred at 30 °C for at least an hour before deposition to allow for the full dissolution of DPHEAI2.

[0082] Fused silica substrates were rinsed with acetone followed by isopropanol, dried with an nitrogen gun, and then plasma cleaned with 300 to 400 mTorr of oxygen plasma at 50 W for 10 minutes.

[0083] 200 pL of the perovskite precursor was deposited onto plasma treated substrates and spun in a two-step sequence. First, the substrate was spun at 1000 rpm for 10 seconds, followed by 4000 rpm for another 30 seconds. When 20 seconds of the cycle was remaining, 200 pL of diethyl ether was rapidly deposited onto the film. Once the cycle was done, the films were then placed onto a preheated hotplate and annealed for 2 minutes at 100 °C.Synthesis of N-(2-aminoethyl)-tetracene-5-carboxylic acid amide

[0084] N-(2-aminoethyl)-tetracene-5-carboxylic acid amide may be prepared by the general synthetic methodology shown in the following reaction scheme.

[0085] According to the general synthetic methodology, tetracene (1 eq.) is combined with 1 ,2-dichlorobenezene (5 mol eq) under an inert atmosphere. A mixture of methyl formanilidine (2 mol eq) and POCh (1.7 mol eq) is then added to the tetracene mixture dropwise and the mixture heated at 100 °C for about 1.5 hours to obtain 5-tetracene aldehyde. The aldehyde is dissolved in isopropyl alcohol under an inert atmosphere. The solution is cooled to 0 °C, degassed and NaCN (5 mol eq) added to the mixture followed by 1,3 -diaminopropane (3.2 mol eq). The solution is stirred for about 5 minutes, MnCh (20 mol eq) is added and the mixture heated at 80 °C for about 1.5 hours to obtain N-(2-aminoethyl)-tetracene-5-carboxylic acid amide.Photoluminescence quantum efficiency (PLQE)

[0086] Photoluminescence quantum efficiency (PLQE) of samples was measured by the following methods.

[0087] Absolute PLQE: The measurements were taken in an 8-inch Labsphere integrating sphere. The sphere was illuminated by a 637 nm, 170 mW, 05.6 mm laser diode (Thorlabs, HL63133DG) collimated by an aspheric lens (Thorlabs, f = 4.51 mm, NA = 0.55, Mounted Aspheric Lens, ARC: 350 - 700 nm, C230TMD-A) in a TE-Cooled mount (Thorlabs, LDM56), powered by a benchtop LD current controller (Thorlabs, LDC205C). Temperature was controlled by a benchtop temperature controller (Thorlabs TED200C). The signal was detected by a Kymera 328i Andor Spectrograph with an DU420A-BVF iDus detector. Results were calibratedagainst a known spectral source - Ocean optics, HL-3 plus, VIS-NIR light source. PLQEs were determined using as presented by de Mello et al.6

[0088] Relative PLQE: Perovskite films were placed in a sample holder and imaged by a series of standard lenses, and were excited using either a 375nm 70 mW 05.6 mm (Thorlabs L375P70MLD) , 450nm 80 mw 03.8 mm (Thorlabs PL450B) or 637nm 170 mW 05.6 mm (Thorlabs, HL63133DG) continuous-wave laser diode. All diodes were collimated by an aspheric lens (Thorlabs, f = 4.51 mm, NA = 0.55, Mounted Aspheric Lens, ARC: 350 - 700 nm, C230TMD-A) in a TE-Cooled mount (Thorlabs, LDM56), powered by a benchtop LD current controller (Thorlabs, LDC205C). Temperature was controlled by a benchtop temperature controller (Thorlabs TED200C). The signal was detected by a Kymera 328i Andor Spectrograph with an DU420A-BVF iDus detector. Results were calibrated against a known spectral source - Ocean optics, HL-3 plus, VIS-NIR light source.

[0089] Using the absolute PLQEs from above for using 637nm excitation allowed the calculation of the relative PLQEs for measurements with 375nm or 450 excitation depending on the organic chromophore targeted. For both methods, the fluence (<2 Wcm'2) of the excitation laser was kept low to reduce two photon absorption.

[0090] The PLQE of each sample with 375nm or 450 nm (PLQEhigfl) excitation was calculated relatively using the absolute PLQE calculated with 637nm excitation (PLQEi0W) of that sample. This was done using the following relationship described by Wurth et al.,7modified slightly to account for the change in the number of incident photons with the sample under each excitation source.

[0091] Here, at excitation wavelength Aex, I-exis the integrated emission spectrum after excitation at Aexand A is the number of photons absorbed by the sample at Aex.

[0092] The number of photons absorbed A^exat excitation wavelength Aexwas calculated by multiplying the number of incident photons, n, with the percent absorbance, %A(Aexat Aex. The number of incident photons n =P^e^Jcis the power of the excitation source at wavelength Aex, h is Planck’s constant, and c is the speed of light. The percentabsorbance of the sample %A(Aex) = 1 — 10Abs<Aex),where Abs(Aex) is the absorbance of the sample at Aex.

[0093] Figure 5 demonstrates the improved PLQE achieved by the hybrid material comprising tetracene and SnPb compared with Sn- or Pb-containing perovskites without tetracene and a Sn-containing perovskite with tetracene (i.e. mismatched).

[0094] Figure 6 shows the photoluminescence quantum efficiency (PLQE) magnitude change at 450 nm and 637 nm for a hybrid material comprising DPHEAMAn-i(Sno.sPbo.5)nl3n+i and a DPHEA layer (coating) at four different layer thicknesses (n=infinity, 20, 10 and 5).Advantageously, the hybrid material with a layer thickness of n=5 exhibits an improved PLQE.

[0095] It is not the intention to limit the scope of the invention to the abovementioned examples only. As would be appreciated by a skilled person in the art, many variations are possible without departing from the scope of the invention as set out in the accompanying indicative claims.REFERENCES1. Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 17, 6050- 6051.2. Jeong, J.; Kim, M.; Seo, J.; Lu, H.; Ahlawat, P.; Mishra, A.; Yang, Y.; Hope, M. A.; Eickemeyer, F. T.; Kim, M.; Yoon, Y. J.; Choi, I. W.; Darwich, B. P.; Choi, S. J.; Jo, Y.; Lee, J. H.; Walker, B.; Zakeeruddin, S. M.; Emsley, L.; Rothlisberger, U.; Hagfeldt, A.; Kim, D. S.; Gratzel, M.; Kim, J. Y. Pseudo-Halide Anion Engineering for a-FAPbI3 Perovskite Solar Cells. Nature 2021, 592 (7854), 381-385.3. Guo, D.; Ma, L.; Zhou, Z.; Lin, D.; Wang, C.; Zhao, X.; Zhang, F.; Zhang, J.; Nie, Z. Charge Transfer Dynamics in a Singlet Fission Organic Molecule and Organometal Perovskite Bilayer Structure. J. Mater. Chem. A 2020, 8 (11), 5572-5579.4. Corre, V. M. Le; Duijnstee, E. A.; Tambouli, O. El; Ball, J. M.; Snaith, H. J.; Lim, J.; Koster, L. J. A. Revealing Charge Carrier Mobility and Defect Densities in Metal Halide Perovskites via Space-Charge-Limited Current Measurements. ACS Energy Lett. 2021, 6 (3), 1087-1094.Bowman, A. R.; Stranks, S. D.; Monserrat, B. Investigation of Singlet Fission-Halide Perovskite Interfaces. Chem. Mater. 2022, 34 (11), 4865-4875. De Mello, J. C.; Wittmann, H. F.; Friend, R. H. An Improved Experimental Determination of External Photoluminescence Quantum Efficiency. Advanced Materials. 1997, 230-232. Wurth, C., GeiBler, D., Behnke, T. et al. Critical review of the determination of photoluminescence quantum yields of luminescent reporters. Anal Bioanal. Chem. 2015 407, 59-78.

Claims

CLAIMS1. A hybrid material comprising a perovskite and a singlet fission compound, wherein the perovskite is layered and the singlet fission compound occupies an interlayer space of the perovskite.

2. The hybrid material of claim 1, wherein, the hybrid material has the formula UyAn- iBnX3n+i, wherein U is the singlet fission compound, A is a cation, B is a metal cation, X is an anion, n is the number of perovskite layers and y is 1 or 2.

3. The hybrid material of claim 2, wherein the hybrid material has the formula L An- lBnX3n+l or UAn-lBnX3n+l.

4. The hybrid material of claim 2 or 3, wherein U is selected from the group consisting of an acene (such as pentacene, tetracene, anthracene or hexacene), a triene (such as a disubstituted hexatriene), a tetraene (such as a disubstituted octatetraene), a benzofuran (such as 1,3-diphenylisobenzofuran), a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene (such as perylene, terrylene or a diimide derivative thereof), a rubrene, an azaacene, a thienoacene, a fulvene, a Cibalackrot-type compound and a combination of any two or more thereof; optionally wherein U is selected from the group consisting of an acene, a benzofuran, a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene, and a combination of any two or more thereof.

5. The hybrid material of any one of claims 2 to 4, wherein U is selected from the group consisting of 1,3-diphenylisobenzofuran, diphenylhexatriene (DPH), diphenyloctatetraene, tetracene, pentacene and derivatives thereof.

6. The hybrid material of any one of claims 2 to 5, wherein the singlet fission compound comprises a cationic moiety.

7. The hybrid material of claim 6, wherein the cationic moiety is an ammonium, a pyridinium or an amidinium.

8. The hybrid material of claim 6 or 7, wherein the cationic moiety is an alkylammonium or ammonio-alkyl amide.

9. The hybrid material of claim 2 or 3, wherein U is selected from the group consisting of an acene (such as pentacene, tetracene, anthracene or hexacene), a triene (such as a disubstituted hexatriene), a tetraene (such as a disubstituted octatetraene), a benzofuran (such as 1,3-diphenylisobenzofuran), a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene (such as perylene, terrylene or a diimide derivative thereof), a rubrene, an azaacene, a thienoacene, a fulvene and a combination of any two or more thereof; wherein U comprises two cationic moieties independently selected from the group consisting of an ammonium, a pyridinium or an amidinium; preferably wherein U is selected from the group consisting of an acene (such as pentacene, tetracene, anthracene or hexacene), a triene (such as diphenylhexatriene), a tetraene (such as diphenyloctatetraene), a benzofuran (such as 1,3-diphenylisobenzofuran), a carotenoid, a diketopyrrolopyrrole, a fluorene, a rylene (such as perylene, terrylene or a diimide derivative thereof), a rubrene, an azaacene, a thienoacene, a fulvene, and a combination of any two or more thereof; wherein U comprises two cationic moieties independently selected from the group consisting of an ammonium, a pyridinium or an amidinium; wherein the cationic moiety is attached directly to U or attached by a linker selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, carboxyl, amide and a combination of any two or more thereof.

10. The hybrid material of any one of claims 2 to 9, wherein U is 2,2'-(((lE,3E,5E)-hexa- l,3,5-triene-l,6-diyl)bis(4,l-phenylene))bis(ethan-l-aminium) (DPHEA), tetracene or N- (2-ammonioethyl)-tetracene-5-carboxylic acid amide (TCEA).

11. The hybrid material of any one of claims 2 to 10, wherein A is selected from the group consisting of an ammonium, an amidinium, a hydrazinium, an imidazolium, a guanidinium, cesium ion (Cs+) and a combination of any two or more thereof.

12. The hybrid material of any one of claims 2 to 10, wherein B is selected from the group consisting of Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Pd2+, Pt2+, Cu2+, Zn2+, Cd2+, Hg2+, Ge2+, Sn2+, Pb2+, Eu2+, Tm2+and Yb2+and a combination of any two or more thereof.

13. The hybrid material of any one of claims 2 to 12, wherein B is selected from the group consisting of Pb2+, Sn2+and combinations thereof.

14. The hybrid material of any one of claims 2 to 13, wherein B is a combination of Pb2+and Sn2+in a ratio of about 0.8:0.2 to about 0.2:0.8.

15. The hybrid material of any one of claims 2 to 13, wherein X is an inorganic anion, organic anion or a combination thereof.

16. The hybrid material of claim 15 wherein the inorganic anion is a halide.

17. The hybrid material of any one of claims 2 to 16, wherein U is DPHEA, A is methylammonium, B is Sn2+o.sPb2+o.5 and X is T.

18. The hybrid material of any one of claims 2 to 16, wherein U is TCEA, A is methylammonium, B is Sn2+o.sPb2+o.5 and X is T.

19. The hybrid material of any one of claims 1 to 18, wherein the hybrid material further comprises a coating comprising a singlet fission compound and / or a chromophore.

20. A process for preparing the hybrid material according to any one of claims 1 to 19, the process comprising: i. combining a precursor of the singlet fission compound, a precursor of the cation and a precursor of the metal cation in the presence of an anion in solution to form a precursor of the hybrid material; and ii. isolating the hybrid material from the solution.

21. The process of claim 20, wherein isolating the hybrid material from the solution comprises a step selected from the group consisting of spin coating, drop casting, blade coating, printing, thermal evaporation and a combination of any two or more thereof.

22. The process of claim 21, wherein the solution comprising the precursor of the hybrid material is spin-coated onto a substrate.

23. The process of any one of claims 20 to 22, wherein the precursor of the singlet fission compound, the precursor of the cation and / or the precursor of the metal cation is provided as a halide salt.

24. Use of the hybrid material according to any one of claims 1 to 19 as a semiconductor or a photocatalyst.

25. A photovoltaic cell comprising the hybrid material according to any one of claims 1 to 19.

26. A light emitting diode (LED) comprising the hybrid material according to any one of claims 1 to 19.

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