GB2624718A

GB2624718A - Compound

Info

Publication number: GB2624718A
Application number: GB2217858.6A
Authority: GB
Inventors: Maciejczyk Michal; Yaacobi-Gross Nir; Kamtekar Kiran
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2022-11-28
Filing date: 2022-11-28
Publication date: 2024-05-29
Also published as: GB202217858D0; WO2024115338A1

Abstract

A compound of formula (I): Wherein Fu is a fullerene; NFA is a non-fullerene acceptor of Formula (II) or (III); L is a linker group; r, s and t are each at least 1; wherein A1 is a divalent heteroaromatic electron accepting group; A2 and A3 are independently monovalent electron-accepting groups; D1, D2 and D3 are independently electron donating groups; B1, B2 and B3 are independently bridging groups; x1 and x2 are each 0-3; y1 and y2 are each at least 1; z1 and z2 are each 0-3; and wherein at least one of B1 or D1 is bound to a fullerene containing group; or at least one of B2, B3 D2 or D3 is bound to a fullerene containing group. Compositions, organic electronic devices and photosensors comprising the disclosed compounds are also described. Formulations comprising the disclosed compounds in one or more solvents, along with methods of preparing organic electronic devices using these formulations is also described.

Description

COMPOUND

BACKGROUND

Embodiments of the present disclosure relate to electron-accepting compounds and more specifically compounds suitable for use as an electron-accepting material in a photoresponsive device.

An organic photodetector may contain a photactive layer of a blend of an electron-donating material and an electron-accepting material between an anode and a cathode. Known electron-accepting materials include fullerenes and non-fullerene acceptors (NFAs).

Yu et al, "Realizing Broadband NIR Photodetection and Ultrahigh Responsivity with Ternary Blend Organic Photodetector" Nanomaterials (Basel) 2022, 12(8), 1378 discloses an organic photodetector containing ternary blend of a donor polymer "PM6", a non-fullerene acceptor "BTP-eC9" and fullerene PC7IBM.

Wu et al, "Fullerene-non-fullerene hybrid acceptors for enhanced light absorption and /5 electrical properties in organic solar cells", Materials Today: Energy Volume 20, June 2021, 100651 discloses fullerene-non-fullerene hybrid acceptors "IP" and "PIP" for use in organic solar cell containing non-fullerene acceptor IDITC and fullerene PC61BM bound to an electron-accepting unit of the IDITC.

Zhou et al, "Hybrid Nonfused-Ring Electron Acceptors with Fullerene Pendant for 2(7 High-Efficiency Organic Solar Cells", ACS Appl. Mater. Interfaces 2021, 13, 1, 1603- 1611 discloses a compound for use in solar cells in which a fullerene is bound to a central benzene ring of a non-fullerene acceptor.

SUMMARY

The present disclosure provides a compound of formula (I): [(Fu)r-L]s-(NFA), (I) -9 -wherein Fu is a fullerene; NFA is a non-fullerene acceptor; L is a linker group; r is at least 1; s is at least 1; t is at least 1 and NFA is a compound of formula (H) or (III): A2 -(B1)x' -(D1)? -(B1)x2 - A2 -(B2)z1 -(D2)y2 -(B3)x3-A' -(B3)x4 -(D3)3/1 -(32)z2 -(III) A1 is a divalent heteroarornatic electron-accepting group; A2 and A3 independently in each occurrence is a monovalent electron-accepting group; D1, D2 and D3 independently in each occurrence is an electron-donating group; Bi. B2, and B3 independently in each occurrence is a bridging group; x1 and x2 are each independently 0, 1,2 or 3; y1 and y2 are each independently at least 1; zi and z2 are each independently 0, 1, 2 or 3; and wherein at least one occurrence of at least one of B1 and DI of formula (II) or at least one occurrence of at least one of B2, B3, D2 and D3 of formula (III) is bound to at least one group of formula (Fu)r-L-.

The present disclosure provides a composition comprising an electron-donating material and an electron-accepting material wherein the electron accepting material is a compound as described herein.

The present disclosure provides an organic electronic device comprising an active layer comprising a compound or composition as described herein.

ro The present disclosure provides a photosensor comprising a light source and an organic photodetector as described herein, wherein the photosensor is configured to detect light emitted from the light source.

The present disclosure provides a formulation comprising a compound or composition as described herein dissolved or dispersed in one or more solvents.

The present disclosure provides a method of forming an organic electronic device as described herein wherein formation of the active layer comprises deposition of a formulation as described herein onto a surface and evaporation of the one or more solvents.

DESCRIPTION OF DRAWINGS

The disclosed technology and accompanying figures describe some implementations of the disclosed technology.

Figure 1 illustrates an organic photoresponsivc device according to some embodiments.

The drawings are not drawn to scale and have various viewpoints and perspectives. The drawings are some implementations and examples. Additionally, some components and/or operations may be separated into different blocks or combined into a single block for the purposes of discussion of some of the embodiments of the disclosed technology. -4 -

Moreover, while the technology is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the technology to the particular implementations described. On the contrary, the technology is intended to cover all modifications, equivalents, and alternatives falling within the scope of the technology as defined by the appended claims.

DETAILED DESCRIPTION

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, io as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. References to a layer "over" another layer when used in this application means that the layers may be in direct contact or one or more intervening layers may be present. References to a layer "on" another layer when used in this application means that the layers are in direct contact.

References to a specific atom include any isotope of that atom unless specifically stated otherwise.

The teachings of the technology provided herein can be applied to other systems, not necessarily the system described below. The elements and acts of the various examples or described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology may include not only additional elements to those implementations noted below, but also may include fewer elements.

These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, -5 -the technology can be practiced in many ways. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

ro To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

The compound of formula (I) is: [(Fu),-Lb-(NFA), (1) Fu is a fullerene.

NFA is a non-fullerene acceptor of formula (II) or (III). L is a linker group.

r is at least I. s is at least 1.

t is at least I. -6 -In some embodiments, s and t are each I. In some embodiments, t is 1 and s is greater than I. preferably 2, 3 or 4. In some embodiments, s is 1 and t is greater than 1, optionally 2, 3 or 4.

The, or each, group (Fu)r-L-is covalently bound directly to an electron-donating unit or a bridging unit of NFA, suitably to an aromatic carbon atom of an electron-donating unit or a bridging unit of NFA. By binding the fullerene to an electron-donating unit or a bridging unit, substituents of an electron-accepting unit of the NFA can be selected so as to tune the electron-accepting properties of the compound of formula (I).

In some embodiments, the compound of formula (I) has an absorption peak greater than /0 900 nm, optionally greater than 1100 nm, optionally greater than 1250 nm. The absorption peak is suitably less than 1500 nm.

Unless stated otherwise, absorption spectra of materials as described herein are measured using a Cary 5000 UV-VIS-NIR Spectrometer. Measurements were taken from 175 nm to 3300 mu using a PbSmart NIR detector for extended photometric range with variable /5 slit widths (down to 0.01 nm) for optimum control over data resolution.

Absorption data are obtained by measuring the intensity of transmitted radiation through a solution sample. Absorption intensity is plotted vs. incident wavelength to generate an absorption spectrum. A method for measuring absorption may comprise measuring a 15 mg / ml solution in a quartz cuvette and comparing to a cuvette containing the solvent only.

Unless stated otherwise, absorption data as provided herein is as measured in toluene solution.

NFA

The non-fullerene acceptor of formula (I) has either formula (I) or (II): A2 -(BI)x' -(DI)y' -(BI)x2 -A3 (Il) -(B2)z' -(D2)3/2 -(33)x3-A1 -(33))0 -(11:0)y3 -(32)Z -Ai is a divalent heteroaromatic electron-accepting group; A2 and A3 independently in each occurrence is a monovalent electron-accepting group; Di. D2 and D3 independently in each occurrence is an electron-donating group; 1131, B2, and B3 independently in each occurrence is a bridging group; xl and x2 are each independently 0, 1,2 or 3, preferably 0 or 1; y2 and yn are each independently at least 1, preferably 1, 2 or 3; and z1 and z2 are each independently 0, 1, 2 or 3, preferably 0 or 1.

rn Each of the electron-accepting groups Ai. A2 and Al has a lowest unoccupied molecular orbital (LUMO) level that is deeper (i.e., further from vacuum) than the LUMO of any of the electron-donating groups DI, D2 or D3 of the compound of formula (1), preferably at least 1 eV deeper. The LUMO levels of electron-accepting groups and electron-donating groups may be as determined by modelling the LUMO level of these groups, in which /5 each bond to adjacent group is replaced with a bond to a hydrogen atom. Modelling may be performed using Gaussian09 software available from Gaussian using Gaussian09 with B3LYP (functional) and LACVP* (Basis set).

Acceptor Unit Al A' is preferably a fused heteroaromatic group comprising at least two fused rings, preferably at least three fused rings.

In some embodiments, Ai of formula (II) is a group of formula (VIII): -8 -(VIII) wherein: Ari is an aromatic or heteroaromatic group; and Y is 0, S. NR4 or 121-C=C-R1 wherein RI in each occurrence is independently H or a substituent wherein two substituents RI may be linked to form a monocyclic or polycyclic ring; and R4 is H or a substituent.

In the case where Ai is a group of formula HI), Arl may be a monocyclic or polycyclic heteroaromatic group which is unsubstituted or substituted with one or more R2 groups to wherein R2 in each occurrence is independently a substituent.

Preferred R2 groups are selected from F; CN; NO2: Clrio alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7 wherein R7 is a Ci_i 2 hydrocarbyl, COO or CO and one or more H atoms of the alkyl may be replaced with F; an aromatic or heteroaromatic group, preferably phenyl, which is unsubstituted or substituted with one or more substituents; and a group selected from -9 -or z40 *^****z41 Z43 Z41. z42 and c743 wherein Z4°, are each independently CR13 or N wherein R13 in each occurrence is H or a substituent, preferably a C1,20 hydrocarbyl group; Y4° and yal are each independently 0, S. NX71 wherein X71 is CN or COOR40; or c x60,,61 A wherein X6° 5 and X61 is independently CN, CF3 or C00R40: W4° and W41 are each independently 0, S. NX71 or CX60-n61 wherein X6° and X61 is independently CN, CF; or COOR"; and R4° in each occurrence is H or a substituent, preferably H or a C1-20 hydrocarbyl group. Exemplary substituents of an aromatic or heteroaromatic group R2 are F. CN, NO2, and C1-12 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S, NR7, lo COO or CO and one or more H atoms of the alkyl may be replaced with F. le as described anywhere herein may be, for example, C142 alkyl, unsubstituted phenyl; or phenyl substituted with one or more C1,6 alkyl groups.

If a C atom of an alkyl group as described anywhere herein is replaced with another atom or group, the replaced C atom may be a terminal C atom of the alkyl group or a non- 7.5 terminal C-atom.

By "non-terminal C atom" of an alkyl group as used anywhere herein means a C atom other than the C atom of the methyl group at the end of an n-alkyl chain or the C atoms of the methyl groups at the ends of a branched alkyl chain.

If a terminal C atom of a group as described anywhere herein is replaced then the resulting 20 group may be an anionic group comprising a countercation, e.g., an ammonium or metal countercation, preferably an ammonium or alkali metal cation.

A C atom of an alkyl substituent group which is replaced with another atom or group as desciibed anywhere herein is preferably a non-terminal C atom, and the resultant substituent group is preferably non-ionic.

-10 -Exemplary monocyclic heteroaromatic groups Arl are oxadiazole, thiadiazole, triazole and 1,4-diazine which is unsubstituted or substituted with one or more substituents. Thiadiazole is particularly preferred.

Exemplary polycyclic heteroaromatic groups AO are groups of formula (V): (V) X1 and X2, are each independently selected from N and CR3 wherein R3 is H or a substituent, optionally H or a substituent R2 as described above.

X3, X4, X5 and X6 are each independently selected from N and CR3 with the proviso that /0 at least one of X3, X4, X5 and X6 is CR3.

Z is selected from 0, S, SO2. NR4, PR4, C(R3)2, Si(R3)2 C=0, C=S and C=C(R5)2 wherein R3 is as described above; R4 is H or a substituent; and R5 in each occurrence is an electron-withdrawing group.

Optionally, each R4 of any NR4 or PR4 described anywhere herein is independently selected from H; C1-20 alkyl wherein one or more non-adjacent C atoms other than the C atom bound to N or P may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; and phenyl which is unsubstituted or substituted with one or more substituents, optionally one or more C1-12 alkyl groups wherein one or more non-adjacent C atoms of the alkyl may be replaced with O. 5, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. -11-Preferably, each R5 is CN, COOR40; cxooxoi wherein X6° and X6I is independently CN, CF3 or COOR4° and R4° in each occurrence is H or a substituent, preferably H or a Ci_2o hydrocarbyl group.

AI groups of formula (VIII) are preferably selected from groups of formulae (VIM) and 5 (VIIIb):

N N

(VIIIb) For compounds of formula (VIIIb), the two RI groups may or may not be linked Preferably, when the two RI groups are not linked each RI is independently selected from _to H; F; CN; NO2; C1-20 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, CO, COO, NR4, PRI, or Si(R3)2 wherein R3 and R4 are as described above and one or more H atoms may be replaced with F; and aryl or hetcroaryl, preferably phenyl, which may be unsubstituted or substituted with one or more suhstituents. Substituents of the aryl or heteroaryl group may be selected from one or more of F; CN; /5 NO2; and alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, CO, COO and one or more H atoms may be replaced with F. Preferably, when the two RI groups are linked, the group of formula (VIIIb) has formula (VIIIb-1) or (VIIIb-2): -12 - (VIIIb-1) (VIIIb-2) Ar2 is an aromatic or heteroarotnatic group, preferably benzene, which is unsubstituted or substituted with one or more substituents. Ar2 may be unsubstituted or substituted with 5 one or more substituents R2 as described above.

Xis selected from 0, S. 502, NR4, PR4, C(R3)2, Si(R3)2 C=0, C=S and C="1:02 wherein R3. R4 and R5 are as described above.

Exemplary electron-accepting groups of formula (VIII) include without limitation: CF3 CF3 AO AO

NHN

-13 -

N N S,

N N

NN AO AO

wherein AO is a CI 20 alkyl group Divalent electron-accepting groups other than formula (WIT) are optionally selected from formulae (IVa)-(IVk) (IVb) -14 -R25 (IVd) R25 R25 N 'N (IVO (IVh) (lye) R12 (We)

N \ /

N 'N (IVg) YA1 is 0 or S. preferably S. -15 -R23 in each occurrence is a substituent, optionally Chi2 alkyl wherein one or more nonadjacent C atoms other than the C atom attached to Z1 may be replaced with 0, S NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. R2 in each occurrence is independently FE F: CN: NOn: Cm, alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may he replaced with F; an aromatic group, optionally phenyl, which is unsubstituted or substituted with one or more substituents selected from F and C1-12 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO; or or z4° 42 z41 Z43 Z43 42 41z, z and *-743 wherein Z4°, are each independently CR13 or N wherein R13 in each occurrence is H or a substituent, preferably a C1-20 hydrocarbyl group; Y4° and Y are each independently 0. S, NX71 wherein X71 is CN or COOR40: or CX60x61 wherein X6° and X61 is independently CN, CF3 or COOR40; W4° and W41 are each independently 0, S, NX7I wherein X71 is CN or COOR40; or CX60x61 wherein x60 and X6' is independently CN, CF3 or COOR4°; and R4° in each occurrence is H or a substituent, preferably H or a CI -20 hydrocarbyl group. Zi is N or P. T1, T2 and T3 each independently represent an aryl or a heteroaryl ring, optionally benzene, which may be fused to one or more further rings. Substituents of T1, T2 and T3, where present, are optionally selected from non-H groups of R25. In a preferred embodiment, T:3 is benzothiadiazole.

R in each occurrence is a substituent, preferably a C1_20 hydrocarbyl group.

-16 -Ars is an arylene or heteroarylene group, optionally thiophene, fluorene or phenylene, which may be unsubstituted or substituted with one or more substituents, optionally one or more non-H groups selected from R25.

Electron-Accepting Groups A2. AI The monovalent acceptor Groups A2 and A3 may each independently be selected from any such units known to the skilled person. A2 and A3 may be the same or different, preferably different.

Exemplary monovalent acceptor units include, without limitation, units of formulae (DCa)-(IXci) R10 (IXa) (IX6) (IXc) D d) / (T C N\c/, R1° (IX° NC\ NN (IXg) NC \CN Rio °R1 -17 -NC (IXh)

NC

R13 (Dci) R13 R15 R15 N \ N

NN R16 R16

(IXm) R15 (IXn) -18 - (IXo) R15 (IXp) Rio / NC Rio U is a 5-or 6-membered ring which is unsubstituted or substituted with one or more substituents and which may be fused to one or more further rings.

The N atom of formula (IXe) may be unsubstituted or substituted.

Rffi is H or a substituent, preferably a substituent selected from the group consisting of C1-12 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; and an aromatic group, optionally phenyl, which is unsubstituted or substituted with one or more substituents selected from F and Chn alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S, NR7, COO or CO.

Preferably, RI° is H. J is C=0 or C=S. NR11 or CR12R13 wherein R11 is CN or COOR40 and R4° is H or a substituent and R12 and R13 are each independently CN. CF3 or COOR40, preferably C=0.

124° in each occurrence is preferably H or a C1_20 hydrocarbyl group R13 in each occurrence is a substituent, optionally C1_12 alkyl wherein one or more non-is C atoms may be replaced with 0, S, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. -19 -R15 in each occurrence is independently H; F; Cm, alkyl wherein one or more nonadjacent C atoms may be replaced with 0, S, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; aromatic group Ar2, optionally phenyl, which is unsubstituted or substituted with one or more substituents selected from F and C1,12 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO; or a group selected from: Y40 z40 *-^,z41 z42 z43-\A/40 R16 is H or a cubcliluenl, preferably a cathclil tient selected from: ro -(Ar3),, wherein Ar3 in each occurrence is independently an unsubstituted or substituted aryl or heteroaryl group, preferably thiophene, and w is 1, 2 or 3; z40 4:^** z41 z42 z43 and C 1 -P alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. -20 -Ar6 is a 5-membered heteroaromatic group, preferably thiophene or furan, which is unsubstituted or substituted with one or more substituents.

Substituents of Ar3 and Ar6, where present, are optionally selected from C1_12 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. T1. T2 and T3 are each independently as described above.

Ar8 is a fused heteroaromatic group which is unsubstituted or substituted with one or more substituents, optionally one or more non-H substituents R1°, and which is bound to an aromatic C atom of B2 and to a boron substituent of B2.

Preferred groups A2 and A3 are groups having a non-aromatic carbon-carbon bond which is bound directly to Dl or D2 or, if present to B2.

Preferably at least one of A2 and A3, preferably both of A2 and ATI, are a group of formula (TXa-1): x60 x6 F' X- x9 (IXa-1) wherein: R1° is as described above; each X7-X10 is independently CR12 or N wherein R12 in each occurrence is I-I or a substituent selected from C1_10 hydrocarbyl and an electron withdrawing group.

-21 -Preferably, die electron withdrawing group is F. Cl, Br or CN, more preferably F. Cl or CN: and X6° and A61 is independently CN. CF3 or COOR4° wherein R4° in each occurrence is H or a substituent. preferably H or a C1_20 hydrocarbyl group. Preferably. X6° and X61 are each CN.

The C1_/0 hydrocarbyl group R12 may be selected from Cu/0 alkyl; unsubstituted phenyl; and phenyl substituted with one or more C1_12 alkyl groups.

In a particularly preferred embodiment, each of X7-X10 is CR12 and each R12 is independently selected from H or an electron-withdrawing group, preferably H, F or CN. _to According to his embodiment. R12 of X8 and X9 is an electron-withdrawing group, preferably F or CN.

Exemplary groups of formula (IXd) include: R13 Exemplary groups of formula (IXe) include: An exemplary group of formula (IXq) is: An exemplary group of formula (IXg) is: An exemplary group of formula (IND is:

CN

wherein Ak is a C 1,12 alkylene chain in which one or more C atoms may be replaced with 0, S. NR7, CO or COO; An is an anion, optionally -S03-; and each benzene ring is independently unsubstituted or substituted with one or more substituents selected from substituents described with reference to RI°.

Exemplary groups of formula (am) arc: R13 R13 R13 R13 An exemplary group of formula (IXn) is: R16 Groups of formula (1Xo) are bound directly to a bridging group B2 substituted with a -B(1214)0 wherein R14 in each occurrence is a substituent, optionally a C1_20 hydrocarbyl group; -> is a bond to the boron atom -B(RI4)2 of R3 or R6; and ---is the bond to B2.

Optionally, R14 is selected from C 1_ p alkyl; unsubstituted phenyl; and phenyl substituted with one or more Ci_12 alkyl groups.

The group of formula (IXo), the B2 group and the B(RI4)2 substituent of B2 may be linked together to form a 5-or 6-membered ring.

Optionally groups of formula (IXo) are selected from: R15 R15 R15 R15 N> R15 R 6 Bridging units Bridging units B', B2 and 1311 are preferably each selected from vinylene, arylene, heteroarylene, arylenevinylene and heteroarylenevinylene wherein the arylene and heteroarylene groups are rnonocyclic or bicyclic groups, each of which may be unsubstituted or substituted with one or more substituents.

Optionally, B1, B2 and B3 are selected from units of formulae (VIa) -(VIn): -24 -R8 R8 R8 R8 R8 (VIa) (VIb) (Vic) orm.

S

(Vif) (VIg) (vti) (V1k) (VII) R8 R8 (Vim) (V In) 128 in each occurrence is independently H or a substituent, preferably H, a group of formula (Fu)r-L-as described with reference to Formula (1), or a substituent selected from F; CN; NO2; Cl_no alkyl wherein one or more non-adjacent C atoms may be replaced with 0, 5, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; phenyl which is unsubstituted or substituted with one or more substituents; and -B(1214)1 wherein R14 in each occurrence is a substituent, optionally a C1_20 hydrocarbyl group. R8 -25 -groups of formulae (Via), (VII)) and (Vic) may be linked to term a bicyclic ring, for example thienopyrazine.

In a particularly preferred embodiment for compounds of formula (III), x3 and x4 are 0 (B3 is not present) and z1 and z2 are each 1 (B2 is present).

R5 is preferably H, C1-20 alkyl or C1-19 alkoxy. Electron-Donating Groups DI, D2 and D3 Electron-donating groups preferably are fused aromatic or heteroaromatic groups, more preferably fused heteroaromatic groups containing 3 or more rings. Particularly preferred electron-donating groups comprise fused thiophene or furan rings, optionally fused rings vi containing thiophene or furan rings and one or more rings selected from benzene, cyclopentadiene, tetrahydropyran, tetrahydrothiopyran and piperidine rings, each of said rings being unsubstituted or substituted with one or more substituents.

Exemplary electron-donating groups Di, D2 and D3 include groups of formulae (VIIa)-(VIIrn).

(VIIa) (VIIb) R52 R5' R52 (VIIc) (VIId) -26 -R51 R5' (Vile) R54 R5 R5' R51 R5" R54 R54 (VIIg) R54 R54 R54 R54 R5' R54 R54 (I Viii) (VIII) (Viii) -27 -(V I Im) wherein YA in each occurrence is independently 0, S or NR55, YA1 in each occurrence is independently 0 or S; ZA in each occurrence is 0, CO, S. NR55 or C(R54)7; R51, R52 R54 and R55 independently in each occurrence is H or a substituent; and R53 independently in each occurrence is a substituent.

Optionally, R51 and R52 independently in each occurrence are selected from H; F; C1-20 alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; an aromatic or heteroaromatic group Ar3 which is unsubstituted or substituted with one or more substituents; and a group of formula (Fu)r-L-as described with reference to Formula (I).

In some embodiments, Ar3 may be an aromatic group, e.g., phenyl.

The one or more substituents of Ar3, if present, may be selected from Ci_p alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F. Preferably, each R54 is selected from the group consisting of: 15 H; F; linear, branched or cyclic C1_20 alkyl wherein one or more non-adjacent C atoms may be replaced by 0, S, NR7, CO or COO wherein R7 is a Ci_12 hydrocarbyl and one or more H atoms of the Ci_20 alkyl may be replaced with F; a group of formula (Ak)u-(Ar7)v wherein Ak is a CI 20 alkylene chain in which one or more non-adjacent C atoms may be replaced with 0, S, NR7, CO or COO; u is 0 or 1; Ar7 in each occurrence is independently an aromatic or heteroaromatic group which is unsubstituted or substituted with one or more substituents; and v is at least 1, optionally 1, 2 or 3; and a group of formula (Fu)r-L-as described with reference to Formula (I).

-28 -Substituents of Ar7. if present, are preferably selected from F; Cl; NO2; CN; and C1-20 alkyl wherein one or more non-adjacent C atoms may be replaced with 0. S. NR7, CO or COO and one or more H atoms may be replaced with F. Preferably, Ar7 is phenyl.

Preferably, each R51 is H or a group of formula (Fu)r-L-.

Optionally, R52 independently in each occurrence is selected from Chi° alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S, NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; phenyl which is unsubstituted or substituted with one or more substituents, optionally one or more CI_12 alkyl groups wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, COO or CO and one or more H atoms of the alkyl may be replaced with F; and a group of formula (Fu)r-L-.

Preferably, R55 as described anywhere herein is H or C1_30 hydrocarbyl group. In some embodiments, y1 and y2 are each 1.

In some embodiments, at least one of y1 and y2 is greater than 1. In these embodiments, the chain of D1 and/or D2 groups, respectively, may be linked in any orientation Electron-donating material A photoactive layer as described herein comprises an electron-donating material. The photoactive layer may be a bulk heterojunction layer comprising an electron-donating material and a compound of formula (I) as described herein. The photoactive layer may comprise two or more sub-layers including an electron-donating sub-layer comprising or consisting of an electron-donating material and an electron-accepting sub-layer comprising or consisting of a compound of formula (I).

Exemplary donor materials are disclosed in, for example, W02013/051676, the contents of which are incorporated herein by reference.

The electron-donating material may be a non-polymeric or polymeric material.

-29 -In a preferred embodiment the electron-donating material is an organic conjugated polymer, which can be a homopolymer or copolymer including alternating, random or block copolymers. The conjugated polymer is preferably a donor-acceptor polymer comprising alternating electron-donating repeat units and electron-accepting repeat units.

Preferred are non-crystalline or semi-crystalline conjugated organic polymers.

Further preferably the electron-donating polymer is a conjugated organic polymer with a low bandgap. typically between 2.5 eV and 1.5 eV, preferably between 2.3 eV and 1.8 eV.

Optionally, the electron-donating polymer has a HOMO level no more than 5.5 eV from _to vacuum level. Optionally, the electron-donating polymer has a HOMO level at least 4.1 eV from vacuum level. As exemplary electron-donating polymers, polymers selected from conjugated hydrocarbon or heterocyclic polymers including polyacene, polyaniline, polyazulene, polybenzofuran, polyfluorene, polyfuran, polyindenofluorene, polyindole, polyphenylene, polypyrazoline, polypyrene, polypyridazine, polypyridine, polytri aryl am i ne, poly(phenylene v n yl ene), poly(3 -substituted thiophene), pol y(3,4- bisubstituted thiophene), polyselenophene, poly(3-substituted selenophene), poly(3,4-bisu b stitutcd sclenophenc), poly(bisthiophenc), poly(terthiophenc), poly(bisselenophene), poly(terselenophene), polythieno [2,3 -b] thiophene, polyth eno 3,2-bl thiophene, pol yben zoth iophene, pol yhenzo 1,2-b:4,5-bldithiophene, polyisothianaphthene, poly(monosubstituted pyrrolc), poly(3.4-bisubstituted pyrrole), poly-1.3.4-oxadiazoles. polyisothianaphthene, derivatives and co-polymers thereof may be mentioned.

Preferred examples of donor polymers are copolymers of polyfluorenes and polythiophenes, each of which may be substituted, and polymers comprising benzothiadiazole-based and thiophene-hased repeating units, each of which may be A particularly preferred donor polymer comprises donor unit (VIIa) provided as a repeat unit of the polymer, most preferably with an electron-accepting repeat unit, for example a divalent electron-accepting units A1 as described herein provided as polymeric repeat units.

Fullerene The, or each, fullerene of the compound of formula (I) may be selected from, without limitation, C60, C70, C76, C78 and C84 fullerenes or a derivative thereof, including, without limitation, PCB M-type fullerene derivatives including phenyl-C61-butyric acid methyl ester (C60PCIIM), TCBM-type fullerene derivatives (e.g. tolyl-C61-butyric acid methyl ester (C60TCBM)), and ThCBM-type fullerene derivatives (e.g. thienyl-C61-butyric acid methyl ester (C60ThCBM).

Fullerene derivatives may have formula (V): rAm

FULLERENE (V)

wherein A, together with the C-C group of the fullerene, forms a monocyclic or fused ring group which may be unsubstituted or substituted with one or more substituents.

Exemplary fullerene derivatives include formulae (Va), (Vb) and (Vc): -31 -c.--C \ (\,,,,

FULLER_ENE (Va) (Vb) (Vc)

wherein R20-1V2 are each independently H or a substituent.

Substituents R20-R32 are optionally and independently in each occurrence selected from the group consisting of aryl or heteroaryl, optionally phenyl, which may be unsubstituted or substituted with one or more substituents; and C1220 alkyl wherein one or more nonadjacent C atoms may be replaced with 0, S. NR7, CO or COO and one or more H atoms may be replaced with F. Substituents of aryl or heteroaryl, where present, are optionally selected from Ci-p alkyl wherein one or more non-adjacent C atoms may be replaced with 0, S. NR7, CO or COO and one or more H atoms may be replaced with F. Linking group /5 The linker group may be selected from an optionally substituted arylene or heteroarylene, preferably phenylene, or a C1-20 alkylene wherein one or more non-adjacent C atoms may be replaced with a optionally substituted phenylene, 0, S, CO, COO, CONR4, NR4, PR4, or Si(R3)7 and wherein R3 and R4 are as described herein and wherein optional substituents of arylene or heteroarylene groups may be selected from F; Cl; NO2; CN; and Cl_no alkyl -32 -wherein one or more non-adjacent C atoms may be replaced with 0, S, NR4, Co or COO and one or more H atoms may be replaced with F. In some embodiments, the, or each, linking group L is formed by reaction of a fullerene substituted with a group LI comprising a first reactive group and a non-fullerene acceptor substituted with one or more groups L2 comprising a second reactive group wherein the first and second reactive groups react to form the linking group L from LI and L2.

The first and second reactive groups may be any groups known to the skilled person which io react to form a covalent bond. This includes first and second reactive groups as follows: - A nucleophile, for example an alcohol, and a leaving group such as a halide or a pseudohalide such as a sulfonic acid ester, which react to form a linking group L comprising an ether group.

- A carboxylic acid or derivative such as an ester, amide, acid chloride or anhydride and an alcohol, thiol or amine which react to form a linking group L comprising a carboxylic ester, thioester or amide group.

- Linkages formed by click chemistry reactions such as an azide-alkyne cycloaddition.

In some embodiments, a carbon-carbon double bond of the fullerene may be reacted with a compound substituted with a NFA to form a cycloadduct of the fullerene substituted with the NFA. In these embodiments, it will be understood that the group L formed by reaction of the fullerene with the substituent of the NFA is fused to the fullerene Methods of forming such a cycloadduct include: - Reaction of a fullerene with a NFA substituted with a substituent containing a or group of formula -C(RI 1)1 wherein 1211 in each occurence is a halogen or pseudohalogen leaving group, preferably Br. This cycloaddition may be as described in, for example, Si, W., Zhang, X., Lu., S. et at. "Manganese powder promoted highly efficient and selective synthesis of fullerene mono-and biscycloadducts at room temperature" Sci Rep 5,13920.

-Reaction of a fullerene compound with a NFA substituted with a group of formula -0(C=0)-CRII-(C=0)0-wherein R" is as defined above, preferably a bromo- -33 -malonate group (Binge] reaction), for example as disclosed in Castro et al. New thiophene-based C60 fullerene derivatives as efficient electron transporting materials for perovskite solar cells, New I Chem., 2018, 42, 14551-14558.

- Reaction of a fullerene compound with a NFA substituted with an azomethine group (Prato reaction), for example as disclosed in Calderon Cerquera et al, "Synthesis, characterization and photophysics of novel BOD1PY linked to dumbbell systems based on Fullerene[60]pyn-olidine and Fulleren460.lisoxazoline" Dyes and Pigments. Vol.. 184. 2021, 108752.

- Reaction of a fullerene compound with a NFA substituted with a non-aromatic carbon-carbon double-bond or benzocyclobutene.

Exemplary compounds of formula (I) include, without limitation:

NC

CN

Fullerene,

NC CN CN CN

NC Fullerene CN

CN NC

NC

0 * * 0 I

CN * * CN

Fullerene

CN

0 Fullerene

NC CN

-35 - -36 -/

R

-37 - -38 - -39 -wherein R'3 is a substituent not containing a fullerene as described above and R is C1-12 alkyl.

Organic Electronic Device A compound of formula (I) may be provided as an active layer of an organic electronic device. In a preferred embodiment, a photoactive layer of an organic photoresponsive device, more preferably an organic photodetector, comprises a compound of formula (I) as described herein.

In some embodiments, the photoactive layer is a bulk heterojunction layer comprising a composition as described herein.

In some embodiments, the photoactive layer comprises two or more sub-layers including an electron-accepting sublayer comprising or consisting of a compound as described herein and an electron-donating sublayer comprising or consisting of an electron-donating 15 material.

In some embodiments, the bulk heterojunction layer or electron-accepting sub-layer contains two or more accepting materials and / or two or more electron-accepting materials.

-40 -In some embodiments, die weight of die electron-donating material(s) to the electron-accepting material(s) is from about 1:0.5 to about 1:2. preferably about 1:1.1 to about 1:2.

Preferably, the electron-donating material has a type II interface with the electron-accepting material of formula (I). i.e. the electron-donating material has a shallower HOMO and LUMO that the corresponding HOMO and LUMO levels of both the fullerene and the NFA of the electron-accepting compound of formula (1). Preferably, the compound of formula (I) has a HOMO level that is at least 0.05 eV deeper, optionally at least 0.10 eV deeper, than the HOMO of the electron-donating material.

Optionally, the gap between the HOMO level of the electron-donating material and the LUMO level of the electron-accepting compound of formula (I) is less than 1.4 eV.

Unless stated otherwise, HOMO and LUMO levels of materials as described herein are as measured by square wave voltammetry (SWV).

In SWV, the current at a working electrode is measured while the potential between the working electrode and a reference electrode is swept linearly in time. The difference current between a forward and reverse pulse is plotted as a function of potential to yield a voltatnmogram. Measurement may be with a CHI 660D Potentiostat.

The apparatus to measure HOMO or LUMO energy levels by SWV may comprise a cell containing 0.1 M tertiary butyl ammonium hexafluorophosphate in acetonitrile; a 3 mm diameter glassy carbon working electrode; a platinum counter electrode and a leak free 20 Ag/AgC1 reference electrode.

Ferrocene is added directly to the existing cell at the end of the expeiiment for calculation purposes where the potentials are detei tined for the oxidation and reduction of ferrocene versus Ag/AgC1 using cyclic voltammetry (CV).

The sample is dissolved in toluene (3 mg / ml) and spun at 3000 rpm directly on to the 25 glassy carbon working electrode.

LUMO = 4.8-E fenocene (peak to peak average) -E reduction of sample (peak maximum).

-41 -HOMO = 4.8-E ferrocene (peak to peak average) + E oxidation of sample (peak maximum).

A typical SWV experiment nins at 15 Hz frequency; 25 mV amplitude and 0.004 V increment steps. Results are calculated from 3 freshly spun film samples for both the HOMO and LUMO data.

Figure 1 illustrates an organic photoresponsive device according to some embodiments of the present disclosure. The organic photoresponsive device comprises a cathode 103, an anode 107 and a bulk heterojunction layer 105 disposed between the anode and the cathode. The organic photoresponsive device may be supported on a substrate 101, io optionally a glass or plastic substrate.

Each of the anode and cathode may independently be a single conductive layer or may comprise a plurality of layers.

At least one of the anode and cathode is transparent so that light incident on the device may reach the bulk heterojunction layer. In some embodiments, both of the anode and /5 cathode are transparent. The transmittance of a transparent electrode may be selected according to an emission wavelength of a light source for use with the organic photodetector.

Figure 1 illustrates an arrangement in which the cathode is disposed between the substrate and the anode. In other embodiments, the anode may be disposed between the cathode and the substrate.

The organic photoresponsive device may comprise layers other than the anode, cathode and bulk heterojunction layer shown in Figure 1. In some embodiments, a hole-transporting layer is disposed between the anode and the bulk heterojunction layer. In some embodiments, an electron-transporting layer is disposed between the cathode and the bulk heterojunction layer. In some embodiments, a work function modification layer is disposed between the bulk heterojunction layer and the anode, and/or between the bulk heterojunction layer and the cathode.

-42 -Figure 1 illustrated herein comprises a bulk heterojunction photoactive layer 105. In other embodiments, photoactive layer 105 comprises two or more sub-layers including an electron-accepting sublayer comprising or consisting of a compound as described herein and an electron-donating sublayer comprising or consisting of an electron-donating material.

The area of the OPD may he less than about 3 cm2, less than about 2 cm2, less than about 1 cm2, less than about 0.75 cm2, less than about 0.5 cm2 or less than about 0.25 cm2. Optionally, each OPD may be part of an OPD array wherein each OPD is a pixel of the array having an area as described herein, optionally an area of less than 1 mm2 optionally ro in the range of 0.5 micron2 -900 micron:.

The substrate may be, without limitation, a glass or plastic substrate. The substrate can be an inorganic semiconductor. In some embodiments, the substrate may be silicon. For example, the substrate can be a wafer of silicon. The substrate is transparent if, in use, incident light is to be transmitted through the substrate and the electrode supported by the substrate.

Formulations The photoactive layer may he formed by any process including, without limitation, thermal evaporation and solution deposition methods.

Preferably, the photoactive layer comprising the compound of formula (I) or (H) is formed by depositing a formulation comprising or consisting of the electron-accepting material(s) and, in the case of a the bulk heterojunction layer, the electron-donating materials dissolved or dispersed in a solvent or a mixture of two or more solvents. The formulation may be deposited by any coating or printing method including, without limitation, spin-coating, dip-coating, roll-coating, spray coating, doctor blade coating, wire bar coating, slit coating, ink jet printing, screen printing, gravure printing and Ilexographic printing.

The one or more solvents of the formulation may optionally comprise or consist of benzene or naphthalene substituted with one or more substituents selected from fluorine, chlorine, CIA° alkyl and Ci_io alkoxy wherein two or more substituents may be linked to form a ring which may be unsubstituted or substituted with one or more CI _6 alkyl groups, -43 -optionally toluene, xylenes, trimethylbenzenes, tetramethylbenzenes, ani sole, indane and its alkyl-substituted derivatives, and tetralin and its alkyl-substituted derivatives.

The formulation may comprise a mixture of two or more solvents, preferably a mixture comprising at least one benzene substituted with one or more substitucnts as described above and one or more further solvents. The one or more further solvents may be selected from esters, optionally alkyl or aryl esters of alkyl or aryl carboxylic acids, optionally a C in alkyl benzoate, benzyl benzoate or dimethoxybenzene. In preferred embodiments, a mixture of trimethylbenzene and benzyl benzoate is used as the solvent. In other preferred embodiments, a mixture of trimethylbenzene and dimethoxybenzene is used as the lo solvent.

The formulation may comprise further components in addition to the electron-accepting material, the electron-donating material (in the case of a bulk heterojunction layer) and the one or more solvents. As examples of such components, adhesive agents, defoLuning agents, deaerators, viscosity enhancers, diluents, auxiliaries, flow improvers colourants, dyes or pigments, sensitizers, stabilizers, nanoparticles, surface-active compounds, lubricating agents, wetting agents, dispersing agents and inhibitors may be mentioned.

Applications A circuit may comprise the OPD connected to a voltage source for applying a reverse bias to the device and / or a device configured to measure photocurrent. The voltage applied to the photodetector may be variable. In some embodiments, the photodetector may be continuously biased when in use.

In some embodiments, a photodetector system comprises a plurality of photodetectors as described herein, such as an image sensor of a camera.

In some embodiments, a sensor may comprise an OPD as described herein and a light source wherein the OPD is configured to receive light emitted from the light source. In some embodiments, the light source has a peak wavelength of at least 900 nm or at least 1000 nm, optionally in the range of 900-1500 nm.

-44 -The present inventors have found that a material comprising an electron-accepting unit of formula (I) may be used for the detection of light at longer wavelengths, particularly 1300-1400 nm.

In some embodiments, the light from the light source may or may not be changed before reaching the OPD. For example, the light may be reflected, filtered, down-converted or up-converted before it reaches the OPD.

The organic photoresponsive device as described herein may be an organic photovoltaic device or an organic photodetector. An organic photodetector as described herein may be used in a wide range of applications including, without limitation, detecting the io presence and / or brightness of ambient light and in a sensor comprising the organic photodetector and a light source. The photodetector may be configured such that light emitted from the light source is incident on the photodetector and changes in wavelength and/or brightness of the light may be detected, e.g., due to absorption by, reflection by and/or emission of light from an object, e.g. a target material in a sample disposed in a light path between the light source and the organic photodetector. The sample may be a non-biological sample, e.g. a water sample, or a biological sample taken from a human or animal subject. The sensor may be, without limitation, a gas sensor, a biosensor, an X-ray imaging device, an image sensor such as a camera image sensor, a motion sensor (for example for use in security applications) a proximity sensor or a fingerprint sensor. A 1D or 2D photosensor array may comprise a plurality of photodetectors as described herein in an image sensor. The photodetector may be configured to detect light emitted from a target analyte which emits light upon irradiation by the light source or which is bound to a luminescent tag which emits light upon irradiation by the light source. The photodetector may be configured to detect a wavelength of light emitted by the target analyte or a luminescent tag bound thereto.

Examples

Compound Example 1

Compound Example 1 may be formed according to the following reaction scheme: -45 -

HO

Ts0C6H130H, K2CO3, DMF

OH

T

BDPSCI, imidazole, DCM icOTBDPS -46 -C6H.13 C6H13 R3S n /-0TBDPS TBDPS0.1 C6H13 CsHia

OTBDPS C6H13 C6H13

CN

PCBA. DMAP, DCC, o-DCB/CS2

OTBDPS

-47 -

Compound Example 2

Compound Example 2 may be formed according to the following reaction scheme: Cycloaddition Suzuki coupling -48 -

Compound Example 3

Step 6 CO 3 C3Ria C8H17 caRia COI CeHi8 Step 9 -49 -CaHi C8Hu Step 7 SnR3 R Sn C6H13C81813 C81-118 Cel-h3

OH Br

Step 1 Step 3 C8H18 Fomylation Step 8

C

NC N

1.2-Dichlorobenzene 190°C -50 -Modelling The HOMO and LUMO energy levels of two NFAs having electron-accepting units A2 and A3 of formula (iXa-1) were modelled.

Table 1

-51 -With reference to Table 1, replacement of an electron-withdrawing group of Model Compound 1 with an alkoxy group results in a significant shallowing of the LUMO level and an increase in the compound's hand gap. By binding the fullerene to a NFA through a donor or bridge unit of the NFA rather than through an electron-accepting unit, such an increase in band gap necessitated by the presence of a linking group, such as an alkoxy group, on the electron accepting unit might be avoided. -3.52 -5.05

HOMO LUMO Eg Slf Eopt /eV /eV Mm /nm -5.28 -3.84 864 2.95 923 12i 878 Structure/ID

NC

Claims

-52 -CLAIMS1. A compound of formula (I): RFu)i-L],-(NFA), wherein Fu is a fullerene; NFA is a non-fullerene acceptor; L is a linker group; r is at least 1; s is at least 1; t is at least 1 and NFA is a compound of formula (II) or (III): A2 -(BI)x' -(DI)y' -(B1),(2 -A3 -(B2)z I -(D2)y2 -(B3)x3-A1 -(B3)x4 -(D3)y3 -(B2)z2 -A3 (III) A1 is a divalent heteroaromatic electron-accepting group; A2 and A3 independently in each occurrence is a monovalent electron-accepting group; DI. D2 and D3 independently in each occurrence is an electron-donating group; -53 -B1, B2, and B3 independently in each occurrence is a bridging group; x1 and x2 are each independently 0, 1, 2 or 3; y and y2 are each independently at least 1; z1 and z2 are each independently 0, 1, 2 or 3; and wherein at least one occurrence of at least one of B1 and D1 of formula (II) or at least one occurrence of at least one of B2, 133, D2 and D3 of formula (HI) is bound to at least one group of formula (Fu)r-L-.
2. The compound of formula (I) according to claim 1 wherein A2 and A3 are not
3. The compound according to claim 1 or 2 wherein the linker group L is fused to the fullerene.
4. The compound according to claim 1 or 2 wherein the linker group L is an optionally substituted phenylene, or a CL20 alkylene wherein one or more non-adjacent C atoms may be replaced with a phenylene, 0, S. CO, COO, CONR4, NR4, PR4, or Si(R3)2 and wherein R3 and R4 are each independently H or a substituent.
5. The compound according to any one of the preceding claims wherein (Fu),-L-is bound to at least one of D1. D2 and D3.
6. The compound according to any one of the preceding claims wherein (Fu),-L-is hound to at least one bridging group B1, B2 and 133.
7. The compound according to any one of the preceding claims wherein at least one of A2 and A3 comprises a non-aromatic carbon-carbon double bond and a carbon atom of the carbon-carbon double bond is bound directly to Di. D2 or D3, or if present, to B1 or B2.-54 - 8. The compound according to any one of the preceding claims wherein A2 and A3 are each independently selected from groups of formulae (111a)-(111q) (Ma) R13NI (11b)(Md) (Me) R1° OTTO NC (Mg) NC> NN R> NN0 NC (11Th)NC-55 -R13 (II1j) R16 R13 R16 (111k) R16 (IIIrn) R15 (11In) (Lao) R15 (HIp) R16 -56 -wherein: U is a 5-or 6-membered ring which is unsubstituted or substituted with one or more substituents and which may be fused to one or more further rings; J is C=0, C=
S, NR11 or CR12R13 wherein R11 is CM or COOR4° and R4° is H or a substituent and R12 and R13 are each independently CN. CF3 or C00R40; R13 in each occurrence is a substituent; R15 in each occurrence is independently H or a substituent Ar6 is a 5-membered heteroaromatic group which is unsubstituted or substituted with one or more substituents; T1. T2 and T3 each independently represent an aryl or a hetcroaryl ring which may be fused to one or more further rings and each of T', T2 and T3 is independently unsubstituted or substituted with one or more substituents; and AO is a fused heteroaromatic group which is unsubstituted or substituted with one or more substituents and which is bound to an aromatic C atom of B1 or B2 and to a boron substituent of B I or B2.
9. The compound according to claim 8 wherein at least one of A2 and A3 is a group of formula (Ina-1)* -57 -wherei n: RI° in each occurrence is H or a substituent; ----represents a linking position to EDG; and R7 in each occurrence is H or a substituent with the proviso that at least one R7 is an electron withdrawing group.
10. A compound according to claim 9 wherein the electron withdrawing group is F, Cl or CM.
11. A composition comprising an electron-donating material and an electron-accepting material wherein the electron accepting material is a compound according to any one of the preceding claims.
12. An organic electronic device comprising an active layer comprising a compound or composition according to any one of the preceding claims.
13. An organic electronic device according to claim 12 wherein the organic electronic device is an organic photoresponsive device comprising a photoactive layer comprising a compound or composition according to any one of claims 1-11 disposed between the anode and cathode.
14. The organic electronic device according to claim 13 wherein the photoactive layer is a bulk heterojunction layer comprising a composition according to claim 11.
15. An organic electronic device according to claim 13 or 14 wherein the organic photorespon sive device is an organic photodetector.
16. A photoscnsor comprising a light source and an organic photodetcctor according to claim 15 wherein the photosensor is configured to detect light emitted from the light source.
17. The photosensor according to claim 16, wherein the light source emits light having a peak wavelength of greater than 900 nm.
18. A formulation comprising a compound or composition according to any one of claims 1 to 11 dissolved or dispersed in one or more solvents.
19. A method of forming an organic electronic device according to any one of claims 12-14 wherein formation of the active layer comprises deposition of a formulation according to claim 18 onto a surface and evaporation of the one or more solvents.