TW202440588A - Compound - Google Patents

Abstract

A compound of formula (I) or (II): A ¹- (B ¹)x ¹- (D ¹)y ¹- (B ¹)x ²- A ¹(I) A ¹- (B ²)x ⁵- (D ²)y ²- (B ³)x ³- A ²- (B ³)x ⁴- (D ³)y ³- (B ²)x ⁶- A ¹(II) A ²is a divalent heteroaromatic electron-accepting group; D ¹, D ²and D ³independently in each occurrence is an electron-donating group; B ¹, B ², and B ³independently in each occurrence is a bridging group; x ¹- x ⁶are each independently 0, 1, 2 or 3; y ¹, y ²and y ³are each independently at least 1; and A ¹in each occurrence is independently a group of formula (III) wherein J is C=O, C=S, NR ¹¹or CR ¹²R ¹³, each Z ¹is N and each Z ²is CR ⁴, or each Z ¹is CR ⁴and each Z ²is N wherein each R ⁴is independently H or a substituent:

Description

Compound

Embodiments of the present invention relate to electron accepting compounds, and more particularly, to compounds used as electron accepting materials in photoresponsive devices.

Organic photodetectors may contain a photoactive layer of a mixture of electron donating and electron accepting materials between an anode and a cathode. Known electron accepting materials include fullerenes and non-fullerene acceptors (NFAs).

Yang et al., "End-capped group manipulation of indacenodithienothiophene-based non-fullerene small molecule acceptors for efficient organic solar cells " , Nanoscale , 2020, 12, 17795-17804, discloses non-fullerene acceptor ITICs with a series of condensed ring end groups for solar cells.

Wang et al., " Enhancement of intra- and inter-molecular π-conjugated effects for a non-fullerene acceptor to achieve high-efficiency organic solar cells with an extended photoresponse range and optimized morphology " , Mater. Chem. Front., 2018, 2, 2006-2012 disclose an ADA-type non-fullerene electron acceptor for solar cells, which has an electron donating (D) core constructed by connecting a 2,5-difluorobenzene ring with two cyclopentadithiophene moieties of 2-(3-oxo-2,3-dihydro- 1H -cyclopenta[ b ]naphthalen-1-ylidene)malononitrile and two electron accepting (A) end groups.

Swick et al., "Fluorinating π-Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells " discloses the compounds ITN-F4 and ITzN-F4 for use in solar cells:

Wu et al., "New Electron Acceptor with End-Extended Conjugation for High-Performance Polymer Solar Cells " , Energy Fuels 2021, 35, 23, 19061-19068, discloses the compound IDTT8-N for solar cells:

Li et al., "Systematic Merging of Nonfullerene Acceptor π-Extension and Tetrafluorination Strategies Affords Polymer Solar Cells with >16% Efficiency " discloses nonfullerene acceptors BT-BIC, LIC, L4F and BO-L4F for solar cells:

The present invention provides a compound of formula (I) or (II): A ¹ - (B ¹ )x ¹ - (D ¹ )y ¹ - (B ¹ )x ² - A ¹ (I) A ¹ - (B ² )x ⁵ - (D ² )y ² - (B ³ )x ³ - A ² - (B ³ )x ⁴ - (D ³ )y ³ - (B ² )x ⁶ - A ¹ (II) wherein: A ² is a divalent heteroaromatic electron accepting group; D ¹ , D ² and D ³ are independently electron donating groups at each occurrence; B ¹ , B ² and B ³ are independently bridging groups at each occurrence; x ¹ to x ⁶ are independently 0, 1, 2 or 3; y ¹ to y ³ are independently at least 1; A ¹ is independently at each occurrence a group of formula (III), (III) wherein: each R ¹ is independently a substituent; R ² is H or a substituent; each R ³ is independently H or a substituent; J is C=O, C=S, NR ¹¹ or CR ¹² R ¹³ , wherein R ¹¹ is CN or COOR ⁴⁰ , and R ⁴⁰ is H or a substituent and R ¹² and R ¹³ are each independently CN, CF ₃ or COOR ⁴⁰ ; and each Z ¹ is N and each Z ² is CR ⁴ , or each Z ¹ is CR ⁴ and each Z ² is N, wherein each R ⁴ is independently H or a substituent.

Optionally, each _R ¹ is independently selected from CN, CF ₃ and COOR ⁴⁰ , wherein R ⁴⁰ at each occurrence is H or a substituent. R ⁴⁰ is preferably H or _{a C 1-20 alkyl} group.

Optionally, each R ³ is an electron withdrawing group.

Optionally, the electron-withdrawing group is selected from Cl, _F , _CN , C _{1-12 fluoroalkyl} and COOR ¹⁵ , wherein _R ¹⁵ is C _1-20 alkyl.

Optionally, each R ⁴ is independently selected from H or an electron withdrawing group.

The present invention provides a composition comprising an electron-donating material and an electron-accepting material, wherein the electron-accepting material is a compound as described in any one of the above technical solutions.

The present invention provides an organic electronic device comprising an active layer comprising the compound or composition described herein.

Optionally, the organic electronic device is an organic photo-responsive device comprising a bulk heterojunction layer disposed between an anode and a cathode, and wherein the bulk heterojunction layer comprises the composition described herein.

Optionally, the organic light responsive device is an organic light detector.

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

Optionally, the light source emits light having a peak wavelength greater than 900 nm.

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

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

Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise," "comprising," and the like are to be interpreted in an inclusive sense, and not in an exclusive or exhaustive sense; in other words, in the sense of "including, but not limited to." In addition, when used in this application, the words "herein," "above," "below," and words of similar import refer to this application as a whole and not to any particular part of this application. Where the context permits, words used in the above specific embodiments in the singular or plural may also include the plural or singular, respectively. The word "or" referring to a list of two or more items includes all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. When used in this application, reference to a layer being "on" another layer means that the layers may be in direct contact or one or more intervening layers may be present. When used in this application, reference to a layer being "on" another layer means that the layers are in direct contact. Unless specifically stated otherwise, reference to a particular atom includes any isotope of that atom.

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

These and other variations can be made to the technology in light of the detailed description below. Although this specification describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed this specification presents, the technology can be practiced in many ways. As mentioned above, when describing certain features or scopes of the technology, the use of specific terms should not be understood to imply that the term is redefined herein to be limited to any specific characteristics, features, or scope of the technology with which the term is associated. In general, unless the specific implementation section explicitly defines such terms, the terms used in the following application scope should not be interpreted as limiting the technology to the specific examples disclosed in this specification. Therefore, the actual scope of the technology covers not only the examples disclosed, but also all equivalent ways of implementing or performing the technology according to the scope of the claims.

In order to reduce the number of patent claims, certain areas of the technology are presented below in certain patent claim forms, but the applicant contemplates various areas of the technology in any number of patent claim forms.

In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the implementation of the disclosed technology. However, it will be apparent to those skilled in the art that the embodiments of the disclosed technology can be practiced without some of these specific details.

The compounds of formula (I) and (II) are A ¹ - (B ¹ )x ¹ - (D ¹ )y ¹ - (B ¹ )x ² - A ¹ (I) A ¹ - (B ² )x ⁵ - (D ² )y ² - (B ³ )x ³ - A ² - (B ³ )x ⁴ - (D ³ )y ³ - (B ² )x ⁶ - A ¹ (II) A ^{1 is a monovalent electron accepting group. A 2 is} a divalent heteroaromatic electron accepting group. D ¹ , D ² and D ³ are independently electron donating groups at each occurrence. B ¹ , B ² and B ³ are independently bridging groups at each occurrence. x ¹ to x ⁶ are each independently 0, 1, 2 or 3, preferably 0 or 1. ^x1 and ^x2 are preferably the same and are preferably both 0 or both 1. ^x3 and ^x4 are preferably the same and are preferably both 0 or both 1, more preferably both 0. ^x5 and ^x6 are preferably the same and are preferably both 0 or both 1. ^y1 , ^y2 and ^y3 are each independently at least 1, preferably 1, 2 or 3. ^y2 and ^y3 are preferably the same.

Each of the electron accepting groups A ¹ , A ² and A ³ has a lowest unoccupied molecular orbital (LUMO) energy level that is deeper (i.e., further from vacuum) than the LUMO of any of the electron donating groups D ¹ , D ² or D ³ of the compound of formula (I), preferably at least 1 eV deeper. The LUMO energy levels of the electron accepting and electron donating groups can be determined by modeling the LUMO energy levels of these groups, wherein each bond to a neighboring group is replaced by a bond to a hydrogen atom. Modeling can be performed using Gaussian09 software obtained from Gaussian, using Gaussian09 with B3LYP (functional) and LACVP* (basis function set).

^A1 is independently at each occurrence a group of formula (III) (III) Each R ¹ is independently a substituent. Preferably, each R ¹ is independently selected from CN; _{C 1-6 fluoroalkyl} , preferably CF ₃ ; and COOR ⁴⁰ , _wherein R ⁴⁰ at each occurrence is _H or a substituent, preferably H or C _1-20 alkyl.

The C _1-20 alkyl group described _herein may be _selected from phenyl groups, which may be _{unsubstituted} or substituted with one or _more substituents selected from _{C 1-12 alkyl} groups and linear, branched or cyclic C _1-20 alkyl groups.

R ² is H or a substituent. Preferably, R ² is H, F, Cl, CN, NO ₂ , C _{1 - 16} alkyl or C _{1 - 16} alkoxy, wherein one or more H atoms of the C _{1 - 16} alkyl or C _{1 - 16} alkoxy may be replaced by F.

Each R ³ is independently H or a substituent, preferably an electron withdrawing group. Preferred electron withdrawing groups are F, Cl, CN, C _{1 - 12} fluoroalkyl and COOR ¹⁵ , wherein R ¹⁵ is C _{1 - 20} alkyl.

J is C=O, C=S, NR ¹¹ or CR ¹² R ¹³ , wherein R ¹¹ , R ¹² and R ¹³ are as described above. J is preferably C=O.

(i) each Z ¹ is N and each Z ² is CR ⁴ , or (b) each Z ¹ is CR ⁴ and each Z ² is N, wherein each R ⁴ is independently H or a substituent, preferably H or an electron withdrawing group. The electron withdrawing group R ⁴ is preferably selected from the electron withdrawing groups described for R ³ .

Preferably, the group of formula (III) has formula (IIIa):

Exemplary groups of formula (III) include (but are not limited to):

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

The present inventors have surprisingly found that compounds of formula (I) or formula (II) having a group ^A1 of formula (III) can have a lower dark current.

The acceptor unit A ² A ² is preferably a fused heteroaromatic group containing at least 2 fused rings, more preferably at least 3 fused rings.

In some embodiments, ^A2 of formula (II) is a group of formula (VIII): (VIII) wherein: Ar ¹ is an aromatic or heteroaromatic group; and Y is O, S, NR ⁶ or R ⁷ -C=CR ⁷ , wherein R ⁷ at each occurrence is independently H or a substituent, wherein two substituents R ⁷ may be linked to form a monocyclic or polycyclic ring; and R ⁶ is H or a substituent.

When A ² is a group of formula (VIII), Ar ¹ may be a monocyclic or polycyclic heteroaromatic group which is unsubstituted or substituted with one or more R ⁹ groups, wherein R ⁹ is independently a substituent at each occurrence.

Preferably, the R ⁹ group is selected from F; CN; NO ₂ ; C _1-20 alkyl, wherein one or _more non- _adjacent C atoms may be replaced by O, S, NR ¹⁷ , wherein _R ¹⁷ is C _1-12 alkyl, _COO or CO, and one or more H atoms of the alkyl may be replaced by F; aromatic or heteroaromatic groups, preferably phenyl, which is unsubstituted or substituted by one or more substituents; and groups selected from the following or wherein Z ⁴⁰ , Z ⁴¹ , Z ⁴² and Z ⁴³ are each independently CR ¹³ or N, wherein R ¹³ at each occurrence is H or a substituent, preferably a C _{1-20 alkyl} group; Y ⁴⁰ and Y ⁴¹ are each independently O, S, NX ⁷¹ , wherein X ⁷¹ is CN or COOR ⁴⁰ ; or CX ⁶⁰ X ⁶¹ , wherein X ⁶⁰ _and X ⁶¹ are independently CN, CF ₃ or COOR ⁴⁰ ; W ⁴⁰ and W ⁴¹ are each independently O, S, NX ⁷¹ or CX ⁶⁰ X ⁶¹ , wherein X ⁶⁰ and X ⁶¹ are independently CN, CF ₃ or COOR ⁴⁰ ; and R ⁴⁰ at each occurrence is H or a substituent, preferably H or _a C _1-20 alkyl group _. Exemplary substituents for the aromatic or heteroaromatic group R ⁹ are F, CN, NO ₂ and C _1-12 alkyl, wherein one _{or more} non-adjacent C atoms may be replaced by O, S, NR ⁷ , COO or CO, and one or more H atoms of the alkyl group may be replaced by F.

R ¹⁷ described anywhere herein may be, for example _{, C 1-12 alkyl} , unsubstituted phenyl, _{or phenyl} substituted with one _or more C _1-6 alkyl groups.

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

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

If a terminal C atom of a group described anywhere herein is replaced, the resulting group may be a cationic group comprising a counter cation, such as an ammonium or metal counter cation, preferably an ammonium or alkali metal cation.

Where described anywhere herein, a C atom of an alkyl substituent which is replaced by another atom or group is preferably a non-terminal C atom, and the resulting substituent is preferably non-ionic.

Exemplary monocyclic heteroaromatic groups Ar ¹ are unsubstituted or substituted with one or more substituents. oxadiazole, thiadiazole, triazole and 1,4-diazole Thiadiazoles are particularly preferred.

Exemplary polycyclic heteroaromatic groups Ar ¹ are groups of formula (V): (V)

^X1 and ^X2 are each independently selected from N and ^CR10 , wherein ^R10 is H or a substituent, optionally H or a substituent ^R9 described above.

X ³ , X ⁴ , X ⁵ and X ⁶ are each independently selected from N and CR ¹⁰ , with the proviso that at least one of X ³ , X ⁴ , X ⁵ and X ⁶ is CR ¹⁰ .

Z is selected from O, S, _SO2 , ^NR6 , ^PR6 , C( ^R10 ) ₂ , Si( ^R10 ) ₂ , C=O, C=S and C=C( ^R5 ) ₂ , wherein ^R10 is as described above; ^R6 is H or a substituent; and ^R5 at each occurrence is an electron withdrawing group.

Optionally, each _R ⁶ in any NR ⁶ or PR ⁶ described anywhere herein is independently selected from H; C _1-20 alkyl, wherein one or more non-adjacent C atoms other than the C atom bound to N or _P may be replaced by O, S, NR ⁷ , COO or CO, and one or more H atoms of the alkyl may be replaced by F; and phenyl, which is unsubstituted or substituted with one or more substituents, optionally one or more C _1-12 alkyl, _wherein one or more non-adjacent C atoms of the alkyl may be replaced by O, S, NR ⁷ , COO or CO, _and one or more H atoms of the alkyl may be replaced by F.

Preferably, each R ⁵ is CN, COOR ⁴⁰ ; or CX ⁶⁰ X ⁶¹ , wherein X ⁶⁰ and X ⁶¹ are independently CN, CF ₃ or COOR ⁴⁰ , and _R ⁴⁰ at each occurrence is H or a substituent, preferably H or _a C _1-20 alkyl group.

The group ^A2 of formula (VIII) is preferably selected from the groups of formula (VIIIa) and (VIIIb): (VIIIa) (VIIIb)

For the compound of formula (VIIIb), the two R ⁷ groups may or may not be linked.

Preferably, when two ^R7 groups are not linked, each ^R7 is independently selected from H; _F ; CN; _NO2 ; _C1-20 alkyl, wherein one or more non-adjacent C atoms may be replaced by O, S, ^NR7 , CO, COO, ^NR6 , ^PR6 or Si( ^R10 ) ₂ , wherein ^R10 and ^R6 are described above and one or _more H atoms may be replaced by F; and aryl or heteroaryl, preferably phenyl, which may be unsubstituted or substituted by one or more substituents. The substituents of the aryl or heteroaryl group may be selected from one or more of the following: F; _{CN; NO 2 ; and C 1-20 alkyl , wherein} one or more non-adjacent C atoms may be replaced by O, S, NR ⁷ , CO, COO, and one or more H atoms may be replaced by F.

Preferably, when two ^R7 groups are linked, the group of formula (VIIIb) has formula (VIIIb-1) or (VIIIb-2): (VIIIb-1) (VIIIb-2)

Ar ² is an aromatic or heteroaromatic group, preferably benzene, which is unsubstituted or substituted by one or more substituents. Ar ² may be unsubstituted or substituted by one or more substituents R ² described above.

X is selected from O, S, SO ₂ , NR ⁶ , PR ⁶ , C(R ¹⁰ ) ₂ , Si(R ¹⁰ ) ₂ , C═O, C═S and C═C(R ⁵ ) ₂ , wherein R ¹⁰ , R ⁶ and R ⁵ are as described above.

Exemplary electron accepting groups of formula (VIII) include, but are not limited to: wherein Ak ¹ is a C _{1 - 20} alkyl group.

The divalent electron accepting group ^A2 other than the group of formula (VIII) is selected from the group of formula (IVa) to (IVj) as appropriate. (IVa) (IVb) (IVc) (IVd) (IVe) (IVf) (IVg) (IVh) (IVi) (IVj)

Y ^A1 is O or S, preferably S.

R ²³ at each occurrence is a substituent, optionally C _1-12 alkyl, wherein one or more non-adjacent C atoms other than the C atom to which Z ³ is attached may be _replaced by O, S, NR ⁶ , COO or _CO , and one or more H atoms of the alkyl group may be replaced by F.

_R ²⁵ is independently at each occurrence H; F; CN _; NO ₂ ; C _1-12 alkyl, wherein one or more non-adjacent C atoms may be replaced by O, S, NR ⁶ , COO or CO and one or more H atoms of the alkyl may be replaced by F; an aromatic group, optionally phenyl, which is unsubstituted or substituted by one or more substituents selected from F and C _1-12 alkyl, wherein one or more non-adjacent C atoms may be replaced by O, S, _NR ⁶ , COO or _CO ; or or wherein Z ⁴⁰ , Z ⁴¹ , Z ⁴² and Z ⁴³ are each independently CR ¹³ or N, wherein R ¹³ at each occurrence is H or a substituent, preferably a C _{1-20 alkyl} group; Y ⁴⁰ and Y ⁴¹ are each independently O, S, NX ⁷¹ , wherein X ⁷¹ is CN or COOR ⁴⁰ ; or CX ⁶⁰ X ⁶¹ , wherein X ⁶⁰ _and X ⁶¹ are each independently CN, CF ₃ or COOR ⁴⁰ ; W ⁴⁰ and W ⁴¹ are each independently O, S, NX ⁷¹ , wherein X ⁷¹ is CN or COOR ⁴⁰ ; or CX ⁶⁰ X ⁶¹ , wherein X ⁶⁰ and X ⁶¹ are each independently CN, CF ₃ or COOR ⁴⁰ ; and R ⁴⁰ at each occurrence is H or _{a substituent, preferably H or a C 1-20 alkyl group} .

Z ³ is N or P.

^T1 , ^T2 and ^T3 each independently represent an aryl or heteroaryl ring which may be fused to one or more other rings, optionally benzene. When present, substituents for ^T1 , ^T2 and ^T3 are optionally selected from non-H groups of ^R25 . In a preferred embodiment, ^T3 is benzothiadiazole.

_R ¹² at each occurrence is a substituent, preferably _a C _1-20 alkyl group.

Ar ⁵ is arylene or heteroarylene, 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 R ²⁵ .

Bridging Units The bridging units ^B1 , ^B2 and ^B3 are preferably each selected from vinylene, arylene, heteroarylene, arylene vinylene and heteroarylene vinylene, wherein the arylene and heteroarylene are monocyclic or bicyclic groups, each of which may be unsubstituted or substituted with one or more substituents.

As appropriate, B ¹ , B ² and B ³ are selected from units of formula (VIa)-(VIn): (VIa) (VIb) (VIc) (VId) (VIe) (VIf) (VIg) (VIh) (VIi) (VIj) (VIk) (VIl) (VIm) (VIn) wherein R ⁵⁵ is H or a substituent; _R ⁸ is independently H or a substituent at each occurrence, preferably H or a substituent selected from the following: F; CN; NO ₂ ; C _1-20 alkyl, wherein one or more non _- adjacent C atoms may be replaced by O, S, NR ⁶ , COO or CO and one or more H atoms of the alkyl may be replaced by F; phenyl, which is _{unsubstituted} or substituted by one or more substituents; and -B(R ¹⁴ ) ₂ , wherein R ¹⁴ is a substituent at each occurrence, optionally a C _1-20 alkyl. The R ⁸ groups of formula (VIa), (VIb) and (VIc ₎ may be linked to form a bicyclic ring, such as thienopyrrolidone. .

^R8 is preferably _{H , C1-20 alkyl or C1-19 alkoxy} .

The electron donating groups ^D1 , ^D2 and ^D3 are preferably fused aromatic or heteroaromatic groups, more preferably fused heteroaromatic groups containing three or more rings. Particularly preferred electron donating groups include fused thiophene or furan rings, optionally fused rings containing a thiophene or furan ring and one or more rings selected from the following: benzene, cyclopentadiene, tetrahydropyran, tetrahydrothiopyran and piperidine rings, each of which is unsubstituted or substituted with one or more substituents.

Exemplary electron donating groups D ¹ , D ² and D ³ include groups of formula (VIIa)-(VIIp): (VIIa) (VIIb) (VIIc) (VIId) (VIIe) (VIIf) (VIIg) (VIIh) (VIIi) (VIIj) (VIIk) (VIIl) (VIIm) (VIIn) (VIIo) (VIIp) wherein ^YA at each occurrence is independently O, S or ^NR55 , ^YA1 at each occurrence is independently O or S; ^XA is C or Si; ^ZA at each occurrence is O, CO, S, ^NR55 or C( ^R54 ) ₂ ; and ^R51 , ^R52 , ^R54 and ^R55 at each occurrence are independently H or a substituent; ^R53 at each occurrence is independently a substituent; and ^Ar4 is optionally a substituted monocyclic or fused heteroaromatic group.

Optionally, R ⁵¹ and R ⁵² are independently selected at each occurrence from H; F; C _1-20 alkyl, wherein one or more non _- adjacent C atoms may be _replaced by O, S, NR ⁷ , COO or CO and one or more H atoms of the alkyl may be replaced by F; an aromatic or heteroaromatic group Ar ³ which is unsubstituted or substituted by one or more substituents.

In some embodiments, Ar ³ can be an aromatic group, such as a phenyl group.

Ar ⁴ is the better choice and has been replaced according to the situation oxadiazole, thiadiazole, triazole and 1,4-diazole . In the case of Ar ⁴ being 1,4-di In this case, 1,4- Can be replaced with another heterocyclic group, or with another heterocyclic group as appropriate. oxadiazole, thiadiazole, triazole, 1,4-diazole And the group of succinimide is condensed.

If present, one or more substituents of Ar ³ may be selected from C _1-12 alkyl, wherein one or more non _- adjacent _C atoms may be replaced by O, S, NR ⁷ , COO or CO and one or more H atoms of the alkyl may be replaced by F.

Preferably, each R ⁵⁴ is selected from the group consisting of: H; F; a linear, branched or cyclic C _{1-20 alkyl} group, wherein one or more non-adjacent C atoms may be replaced by O, S, NR ⁷ , _CO or COO, wherein R ¹⁷ is a C _{1-12 alkyl} group, and one or more H atoms of _the C _{1-20 alkyl} group may be replaced by _F ; and

A group of formula (Ak)u-( _Ar ⁷ )v, wherein Ak is a C _1-20 alkylene chain, wherein one or more non _- adjacent C atoms may be replaced by O, S, NR ⁷ , CO or COO; u is 0 or 1; Ar ⁷ is independently, at each occurrence, an aromatic or heteroaromatic group, which is unsubstituted or substituted by one or more substituents; and v is at least 1, and optionally 1, 2 or 3.

The substituents of Ar ⁷ (if present) are preferably selected from F; _Cl ; NO ₂ ; CN; and C _1-20 alkyl, wherein one or more non-adjacent C atoms may be replaced by O, S, NR ⁷ , _CO or COO, and one or more H atoms may be replaced by F. Preferably, Ar ⁷ is phenyl.

Preferably, each R ⁵¹ is H.

Optionally, R ⁵³ is independently selected at each occurrence from C _1-20 alkyl, wherein one or more non _- adjacent C atoms may be _replaced by O, S, NR ⁷ , COO or CO and one or more H atoms of the alkyl _may be _{replaced by F; phenyl, which is unsubstituted or substituted with one or more substituents, optionally one or more C 1-12 alkyl} , wherein one or more non-adjacent C atoms may be replaced by O, S, NR ⁷ , COO or CO and one or more H atoms of the alkyl may be replaced by F.

Preferably, ^R55 as described anywhere _herein is H _{or C1-30} alkyl.

In a preferred embodiment, D ¹ , D ² and D ³ are each independently a group of formula (VIIa). Exemplary groups of formula (VIIa) include (but are not limited to): wherein Hc is independently at each occurrence a C _{1 - 20} alkyl group, such as a C _{1 - 20} alkyl group, an unsubstituted aryl group or an aryl group substituted with one or more C _{1 - 12} alkyl groups. Aryl is preferably phenyl.

In some embodiments, ^y1 in formula (I) is 1.

In some embodiments, ^y2 and ^y3 of formula (II) are each 1.

In some embodiments, at least one of ^y1 of formula (I) or ^y2 and y3 of formula (II ⁾ is greater than 1. In these embodiments, the chains of the ^D1 , ^D2 or ^D3 groups can be connected in any orientation. For example, when ^D1 is a group of formula (VIIa) and ^y1 is 2, -[ ^D1 ] _y1- can be selected from any of the following:

Exemplary compounds of formula (I) include (but are not limited to):

Electron Donating Materials The bulk heterojunction layers described herein comprise an electron donating material and a compound of formula (I) described herein.

Exemplary donor materials are disclosed, for example, in WO2013/051676, the contents of which are incorporated herein by reference.

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

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

Preferably, it is a non-crystalline or semi-crystalline conjugate organic polymer.

Also preferably, the electron donating polymer is a conjugated organic polymer having a band gap generally 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 energy level of no more than 5.5 eV from the vacuum energy level. Optionally, the electron donating polymer has a HOMO energy level of at least 4.1 eV from the vacuum energy level. As exemplary electron donating polymers, there can be mentioned polymers selected from conjugated hydrocarbon or heterocyclic polymers, including polyacene, polyaniline, polyazulene, polybenzofuran, polyfluorene, polyfuran, polyindole, polyphenylene, polypyrazoline, polypyrene, polyhedral ... , polypyridine, polytriarylamine, poly(phenylene vinylene), poly(3-substituted thiophene), poly(3,4-bissubstituted thiophene), polyselenophene, poly(3-substituted selenophene), poly(3,4-bissubstituted selenophene), poly(dithiophene), poly(terthiophene), poly(diselenophene), poly(triselenophene), polythieno[2,3-b]thiophene, polythieno[3,2-b]thiophene, polybenzothiophene, polybenzo[1,2-b:4,5-b']dithiophene, polyisobenzothiophene, poly(monosubstituted pyrrole), poly(3,4-bissubstituted pyrrole), poly-1,3,4- Oxadiazole, polyisobenzothiophene, their derivatives and copolymers.

Preferred examples of the donor polymer are copolymers of polyfluorene and polythiophene, each of which may be substituted; and polymers comprising benzothiadiazole-based and thiophene-based repeating units, each of which may be substituted.

Particularly preferred donor polymers comprise donor units (VIIa) provided as repeating units of the polymer, and most preferred polymers have electron accepting repeating units, such as divalent electron accepting units ^A1 as described herein provided as polymerized repeating units.

Another particularly preferred donor polymer comprises repeating units of formula (X): (X) wherein R ¹⁸ and R ¹⁹ are _each independently selected from H; F; C _{1-12 alkyl} , wherein one or more non-adjacent, non-terminal C atoms may be replaced by O, S, COO or CO, and one or more H atoms of the alkyl may be replaced by F; or an aromatic or _{heteroaromatic} group Ar ⁶ which is unsubstituted or substituted with one or more substituents selected from F and C _1-12 alkyl, wherein one or more non-adjacent, non-terminal _C atoms may be replaced by O, S, COO or CO.

The donor polymer is preferably a donor-acceptor (DA) copolymer comprising a donor repeat unit, such as a repeat unit of formula (VIIa) or (X), and an acceptor repeat unit.

Organic Electronic Devices The compound of formula (I) or (II) can be provided as an active layer of an organic electronic device. In a preferred embodiment, the bulk heterojunction layer of an organic photoresponsive device, more preferably an organic photodetector, comprises the composition described herein.

The bulk heterojunction layer comprises or consists of an electron donating material and an electron accepting compound of formula (I) or formula (II) described herein.

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

In some embodiments, the weight ratio of the electron donating material to the electron accepting material is about 1:0.5 to about 1:2, preferably about 1:1.1 to about 1:2.

Preferably, the electron donating material and the electron accepting material have a type II interface, that is, the electron donating material has a HOMO and a LUMO that are shallower than the corresponding HOMO and LUMO energy levels of the electron accepting material. Preferably, the compound of formula (I) or (II) has a HOMO energy level that is at least 0.05 eV deeper than the HOMO of the electron donating material, and optionally at least 0.10 eV deeper.

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

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

FIG1 shows an organic light responsive device according to some embodiments of the present invention. The organic light responsive device comprises a cathode 103, an anode 107 and a bulk heterojunction layer 105 disposed between the anode and the cathode. The organic light responsive device can be supported on a substrate 101, which can be a glass or plastic substrate.

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

At least one of the anode and cathode is transparent so that light incident on the device can reach the bulk heterojunction layer. In some embodiments, both the anode and cathode are transparent. The transmittance of the transparent electrode can be selected based on the emission wavelength of the light source used with the organic photodetector.

Figure 1 shows a configuration 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 photoresistor device may include layers other than the anode, cathode, and bulk heterojunction layer shown in FIG1 . In some embodiments, the hole transport layer is disposed between the anode and the bulk heterojunction layer. In some embodiments, the electron transport layer is disposed between the cathode and the bulk heterojunction layer. In some embodiments, the work function modification layer is disposed between the bulk heterojunction layer and the anode and/or between the bulk heterojunction layer and the cathode.

The area of the OPD may be 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 array of OPDs, wherein each OPD is a pixel of the array having an area as described herein, optionally less than 1 ^mm2 , optionally in the range of 0.5 ^microns2 to 900 ^microns2 .

The substrate may be, but is not limited to, a glass or plastic substrate. The substrate may be an inorganic semiconductor. In some embodiments, the substrate may be silicon. For example, the substrate may be a silicon wafer. In use, if incident light is transmitted through the substrate and the electrode is supported by the substrate, then the substrate is transparent.

The bulk heterojunction layer contains a compound of formula (I) or formula (II) described herein and an electron donating compound. The bulk heterojunction layer may be composed of these materials or may include one or more other materials, such as one or more other electron donating materials and/or one or more other electron accepting compounds.

Fullerenes In some embodiments, the compound of formula (I) or formula (II) is the only electron-accepting material of the bulk heterojunction layer described herein.

In some embodiments, the bulk heterojunction layer contains a compound of formula (I) or (II) and one or more other electron accepting materials. Preferably, the other electron accepting material is fullerene. The inventors have surprisingly found that the combination of a compound of formula (I) or (II) and fullerene can enhance the external quantum efficiency of the OPD with little or no increase in dark current.

The weight ratio of the compound of formula (I) or (II):fullerene acceptor may be in the range of about 1:0.1 to 1:1, preferably in the range of about 1:0.1 to 1:0.5. The fullerene may be selected from, but not limited to, C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ and C ₈₄ fullerenes or derivatives thereof, including but not limited to PCBM-type fullerene derivatives (including phenyl-C ₆₁ -butyric acid methyl ester (C ₆₀ PCBM)), TCBM-type fullerene derivatives (such as tolyl-C ₆₁ -butyric acid methyl ester (C ₆₀ TCBM)) and ThCBM-type fullerene derivatives (such as thienyl-C ₆₁ -butyric acid methyl ester (C ₆₀ ThCBM)).

The fullerene derivative may have formula (V): (V) wherein A together with the CC group of the fullerene forms a monocyclic or condensed ring group which may be unsubstituted or substituted with one or more substituents.

Exemplary fullerene derivatives include formula (Va), (Vb) and (Vc): (Va) (Vb) (Vc) wherein R ²⁰ to R ³² are each independently H or a substituent.

The substituents R ²⁰ to R ³² are optionally and independently selected at each occurrence from the group consisting of: aryl or heteroaryl, optionally phenyl, which may be unsubstituted or substituted with one or more substituents; and C _1-20 alkyl, wherein one or more non _- adjacent C atoms may be replaced by _O , S, NR ⁷ , CO or COO, and one or more H atoms may be replaced by F.

Substituents of the aryl or heteroaryl groups (when present) are optionally selected from C _{1-12 alkyl} groups, wherein one or more non-adjacent C atoms may be replaced by O, S, NR ⁷ , _CO or COO and one or more H atoms may be replaced by F.

The bulk heterojunction layer may be formed by any process including but not limited to thermal evaporation and solution deposition.

Preferably, the bulk heterojunction layer is formed by depositing a formulation comprising an electron donating material, an electron accepting material, and any other components of the bulk heterojunction layer dissolved or dispersed in a solvent or a mixture of two or more solvents. The formulation can be deposited by any coating or printing method including but not limited to spin coating, dip coating, roll coating, spray coating, doctor blade coating, wire rod coating, slit coating, inkjet printing, screen printing, gravure printing, and flexographic printing.

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, _{C1-10 alkyl} and _{C1-10 alkoxy} , wherein two or more substituents may be linked to form a ring, which _may be unsubstituted _or substituted with one or more _{C1-6 alkyl} , optionally toluene, xylene, trimethylbenzene, tetramethylbenzene, _anisole , indane and alkyl-substituted derivatives thereof, and tetrahydronaphthalene and alkyl-substituted derivatives thereof.

The formulation may comprise a mixture of two or more solvents, preferably a mixture comprising at least one benzene substituted with one or more of the substituents described above and one or more other solvents. The one or more other solvents may be selected from esters, optionally alkyl or aryl esters of alkyl or aryl carboxylic acids, optionally C _{1-10 alkyl} benzoates, benzyl benzoate or dimethoxybenzene. In a preferred embodiment, a mixture of trimethylbenzene and benzyl benzoate is used _as a solvent. In other preferred embodiments, a mixture of trimethylbenzene and dimethoxybenzene is used as a solvent.

The formulation may contain other components in addition to the electron accepting material, the electron donating material and the one or more solvents. As examples of such components, there may be mentioned adhesives, defoamers, deaerators, viscosity enhancers, diluents, adjuvants, flow improvers, colorants, dyes or pigments, sensitizers, stabilizers, nanoparticles, surface active compounds, lubricants, wetting agents, dispersants and inhibitors.

The application circuit may include an 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 includes a plurality of photodetectors as described herein, such as an image sensor of a camera.

In some embodiments, the sensor may include an OPD and a light source as described herein, 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, preferably in the range of 900 to 1500 nm.

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

The organic photo-responsive devices described herein may be organic photovoltaic devices or organic photodetectors. The organic photodetectors described herein may be used in a wide range of applications, including but not limited to detecting the presence and/or brightness of ambient light; and in sensors comprising an organic photodetector and a light source. The photodetector may be configured so that light emitted from the light source is incident on the photodetector, and changes in the wavelength and/or brightness of the light may be detected, for example, due to absorption, reflection and/or emission of light by an object (e.g., a target material in a sample disposed in an optical path between the light source and the organic photodetector). The sample may be a non-biological sample, such as a water sample; or a biological sample taken from a human or animal individual. 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 (e.g., used in security applications), a proximity sensor, or a fingerprint sensor. A 1D or 2D photo sensor array may include a plurality of photodetectors described herein in an image sensor. The photodetector may be configured to detect light emitted from a target analyte that emits light upon illumination by a light source, or to detect light emitted by a target analyte bound to a luminescent tag that emits light upon illumination by a light source. The photodetector may be configured to detect the wavelength of light emitted by a target analyte or a luminescent tag bound thereto.

Examples Example 1 The group of formula (III-1) can be formed according to the following reaction process:

Step 1 : 1 (250 g, 1.06 mol) was dissolved in 2.5 L of dichloroethane. N-bromosuccinimide (754 g, 4.24 mol) was added portionwise to the reaction mixture, and it was heated at 75 °C for 16 hours. Solid impurities were filtered out and washed with heptane. The filtrate was concentrated under vacuum to give 255 g of crude material. The product 2 was used in the next step without further purification.

Step 2 : 2 (99.9 g, 434 mmol) and 3 (55 g, 310 mmol) were dissolved in 1 L of ethanol. p-Toluenesulfonic acid (4.69 g, 24.7 mmol) was added to the reaction mixture and heated at 68 °C for 3 hours. The reactant was then concentrated under vacuum to give 105 g of a crude product, which was purified by column chromatography with dichloromethane to give 80 g of the desired product.

Step 3 : 4 (50 g, 134 mmol) was dissolved in 500 mL of methanol. Lithium hydroxide monohydrate (12.9 g, 308 mmol) was added to the reaction mixture and stirred at room temperature for 16 hours. The reaction mixture was filtered and the obtained solid was stirred in dilute hydrochloric acid for 3 hours. The solid was filtered to obtain 30 g of the desired product 5 .

Step 4 : 5 (30 g, 104 mmol) and acetic anhydride (600 mL) were combined in a flask. The reaction mixture was heated at 130 °C for 6 hours. Afterwards, it was cooled and concentrated under reduced pressure to obtain 30 g of crude product 6 , which was used directly in the next step without further purification.

Step 5 To a stirred solution of 6 (30 g, 111 mmol) in acetic anhydride (240 mL) was added triethylamine (11.2 g, 111 mmol). Tributyl acetoacetate (18.3 g, 116 mmol) was added dropwise thereto. The reaction mixture was stirred at room temperature for 16 hours and then slowly poured into another flask containing 1.5 N hydrochloric acid (400 mL) and 400 mL of ice water. This was then stirred at room temperature for 48 hours. The resulting solid was separated by filtration to give 15 g of the desired product 7 as a black solid, which was used in the next step without further purification.

Step 6 7 (5 g, 18.7 mmol) was dissolved in pyridine (90 ml). Malononitrile (3.08 g, 46.7 mmol) was added thereto and the mixture was stirred at room temperature for 2 hours. The reactant was concentrated under reduced pressure to give 9 g of crude material, which was purified by neutral alumina column chromatography using dichloromethane and 1% triethylamine/methanol. The obtained product was wet-triturated with hexane/dichloromethane and filtered to give 2.013 g of pure III - 1 product as triethylamine salt (98.81% by HPLC).

Example 2 The group of formula (III-2) can be formed according to the following reaction process:

Example 3 The group of formula (III-3) can be formed according to the following reaction process:

Step 1 is as in III-1.

Step 2 3 ( 150 g, 564 mmol) and 2 (181 g, 789 mmol) were dissolved in ethanol (2.5 L). p-Toluenesulfonic acid monohydrate (8.57 g, 45.1 mmol) was added to the reaction mixture, and it was heated at 65 °C for 4 hours. Subsequently, it was concentrated under vacuum to give 390 g of crude product 4 , which was used in the next step without further purification.

Step 3 4 (330 g, 717 mmol) was dissolved in 3 L of methanol. Lithium hydroxide monohydrate (68.8 g, 1.64 mol) dissolved in 250 mL of water was added dropwise thereto. The resulting solid was filtered and stirred with 1.5 N HCl solution (2 L) for 3 hours. The precipitate was separated by filtration, washed with 2 L of water and dried under vacuum to give 220 g of pure material 5 as an off-white solid.

Step 4 5 (150 g, 398 mmol) was dissolved in acetic anhydride (1.5 L, 14.6 mmol). The reaction mixture was heated at 130 °C for 16 hours. After completion, the reaction mixture was concentrated under vacuum to obtain 125 g of 6 , which was used in the next step by further purification.

Step 5 6 (50 g, 139 mmol) and acetic anhydride (50 g, 139 mmol) were combined and cooled to 0 °C. Triethylamine (20 mL, 0.197 mmol) was added followed by tributyl acetoacetate (16.8 g, 145 mmol) and the reaction mixture was stirred at room temperature for 16 hours. After this time, the mixture was concentrated under reduced pressure and stirred with 1.5 N hydrochloric acid (480 mL) and water (1920 mL) for 3 days. Upon completion, the mixture was filtered to give 35 g of the desired product 7. LCMS indicated 60% purity and this material was then used in the next step.

Step 6 7 (30 g, 84.2 mmol) was dissolved in toluene (1 L), and ethane-1,2-diol (104 g, 1.68 mol) and p-toluenesulfonic acid (3.19 g, 16.8 mmol) were added. The reaction mixture was heated to 135 °C for 16 hours. During this time, water was frequently removed using a Dean-Stark apparatus. Upon completion, the mixture was cooled to room temperature and filtered through a celite bed, washed with ethyl acetate followed by water, dried over sodium sulfate and concentrated under vacuum to give 38 g of crude product 8 .

Step 7 To o-xylene (150 mL) containing 8 (5 g, 11.2 mmol) were added potassium hexacyanoferrate (III) (4.93 g, 13.4 mmol), 1-butylimidazole (2.91 g, 23.5 mmol) and copper (I) iodide (1.27 g, 6.71 mmol). The reaction mixture was heated at 148 °C for 24 hours. Thereafter, potassium hexacyanoferrate (0.74 g), copper iodide (0.2 g) and 1-butylimidazole (0.46 mL) were added and the mixture was further heated to 148 °C for 24 hours. After completion, the mixture was cooled to room temperature and filtered through a diatomaceous earth pad, and the filtrate was washed with water and extracted with ethyl acetate. The organic phase was dried over sodium sulfate and concentrated under vacuum to give 7 g of the crude intermediate. This material was further purified by column chromatography using a mixture of ethyl acetate and hexanes to give 3.5 g of the desired product 9 as a yellow solid.

Step 8 9 (3 g, 8.92 mmol) was dissolved in trifluoroacetic acid (21 mL). The reaction mixture was heated at 40 °C for 3 h. It was then concentrated under vacuum at 30 °C to give the crude material 10 , 50% desired product by LCMS, which was used as is in the next step.

Step 9 To ethanol (120 mL) containing malononitrile (0.304 g, 4.61 mmol) and sodium acetate (9.18 g, 112 mmol) was added dropwise 10 (1.5 g, 5.13 mmol) dissolved in 250 ml of ethanol. The reaction mixture was stirred at room temperature for 3 hours and then concentrated under vacuum to obtain a crude product. The crude product was purified by column chromatography using a dichloromethane/methanol solvent system. The obtained product was suspended in ethyl acetate and stirred for 30 minutes and filtered to obtain 0.5 g of III-3 product (purity 88%) as a dark solid.

Compound Example 1 Compound Example 1 can be formed according to the following reaction scheme:

Compounds 2 to 4 shown in Table 1 were formed. Comparative compounds 2-4 are also shown. Table 1 Compound Structure Compound Example 1 Comparison with compound 1 Compound Example 2 Comparison with compound 2 Compound Example 3 Comparison with compound 3 Compound Example 4 Comparison with compound 4

Measurement Methods HOMO and LUMO energy levels were measured by square wave voltammetry (SWV).

In SWV, the current at the working electrode is measured while the potential between the working electrode and the reference electrode is swept linearly over time. The differential current between the forward pulse and the reverse pulse is plotted according to the change in potential to obtain a voltammogram. The CHI 660D potentiostat can be used for measurement.

The apparatus used to measure the HOMO or LUMO energy level by SWV may include the following: a cell containing 0.1 M tertiary butylammonium hexafluorophosphate in acetonitrile; a 3 mm diameter glassy carbon working electrode; a platinum counter electrode and a leak-free Ag/AgCI reference electrode.

At the end of the experiment, ferrocene was added directly to the existing cell for calculation purposes, where the potential for oxidation and reduction of ferrocene relative to Ag/AgCI was determined using cyclic voltammetry (CV).

The samples were dissolved in toluene (3 mg/ml) and spun directly onto a glassy carbon working electrode at 3000 rpm.

LUMO = 4.8 - E Ferrocene (peak to peak average) - E Sample reduced (peak maximum).

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

A typical SWV experiment was run at 15 Hz frequency; 25 mV amplitude and 0.004 V increment step. Results were calculated from three freshly centrifuged film samples for both HOMO and LUMO data.

Absorption spectra were measured using a Cary 5000 UV-VIS-NIR spectrometer. For optimal control over data resolution, measurements were acquired from 175 nm to 3300 nm using a PbSmart NIR detector with variable slit width (down to 0.01 nm) for extended photometric range.

Unless otherwise stated, absorbance values are for solutions. Absorption data are obtained by measuring the intensity of transmitted radiation through a sample of a solution. The absorption intensity is plotted against the incident wavelength to produce an absorption spectrum. A method for measuring absorbance may include measuring a 15 mg/ml solution in a quartz cell and comparing it to a cell containing only solvent.

Unless otherwise stated, the solution absorbance data provided herein were measured in toluene solutions.

The material data is shown in Table 2. The compound examples have longer peak absorption wavelengths than the corresponding comparative compounds. Table 2 Compound Membrane HOMO ( eV ) Membrane LUMO ( eV ) Membrane absorptivity λ ( nm ) Solution absorbance λ ( nm ) Comparison with compound 1 -5.26 -4.23 1150 (o-DCB) 954 (o-DCB) Compound Example 1 -5.45 -4.27 1304 (Toluene) 1035 (Toluene) Compound Example 2 -5.46 -4.21 1081 (TMB) 996 (Toluene) Comparison with compound 2 -5.41 -4.09 1039 (Toluene) 965 (Toluene) Compound Example 3 -5.41 -4.23 1102 (TMB) 971 (TMB) Comparison with compound 3 -5.28 -4.23 998 (TMB) 901 (TMB) Compound Example 4 -5.44 -4.21 1152 (TMB) 1028 (TMB) Comparison with compound 4 -5.38 -4.14 1068 (Toluene) 1038 (Toluene) o-DCB : o - dichlorobenzeneTMB : 1,3,4- trimethylbenzene

2 , Compound Example 1 has a higher absorption intensity than Comparative Compound 1 under the same absorption conditions.

3 and as shown in Table 1, the film of Compound Example 1 formed by spin coating from o-dichlorobenzene absorbs at about 1300 nm, which is about 150 nm longer than the film of Comparative Compound 1 formed by spin coating from toluene.

Device Example 1 A glass substrate coated with a 150 nm thick indium tin oxide (ITO) layer was coated with an aqueous solution containing 0.2% polyethyleneimine (PEIE) to form a film of about 5 nm, thereby modifying the work function of ITO. A bulk heterojunction layer of about 500 nm thick of a mixture of donor polymer 1: compound example 1 (1:0.7, by weight) was deposited on top of the modified ITO layer by rod coating from a 10 mg/ml solution of o-dichlorobenzene/butyl benzoate solvent mixture (90:10 v/v). An anode stack of MoO ₃ (10 nm) and ITO (50 nm) was formed on the bulk heterojunction by thermal evaporation (MoO ₃ ) and sputtering (ITO).

Device Example 1A The device was prepared as described for Device Example 1, except that in addition to Donor Polymer 1 and Compound Example 1, the solution used to form the bulk heterojunction layer containing fullerene PCBM had a weight ratio of Donor Polymer 1: Compound Example 1:PCBM of 1:0.7:0.3.

Comparative Device 1 The device was prepared as described for Device Example 1A, except that Comparative Compound 1 was used instead of Compound Example 1.

Referring to Figure 4, the external quantum efficiency of device examples 1 and 1A peaks at about 1300 nm. Including PCBM increases the EQE.

Referring to FIG. 5 , the EQE of comparative device 1 reaches a peak at about 900 nm.

6 , the dark currents of the device examples 1 and 2 under a reverse bias voltage of -3 V are much lower than the dark current of the comparative device 1.

Device Examples 2 to 4 Device Examples 2 to 4 were prepared as described for Device Example 1A, except that: - Compound Examples 2 to 4 were used instead of Compound Example 1, respectively - The solvents used to form the bulk heterojunction layer were as described in Table 3 - For Device Examples 2 and 4, the weight ratio of donor polymer 1: Compound Example: PCBM was 1:0.875:0.625

Comparative Devices 2 to 4 containing Comparative Compounds 2 to 4 were formed in the same manner as in the corresponding device examples. Table 3 Device Solvent External quantum efficiency ( % ) Dark current ( mA / cm2 ) Comparison device 1 o-DCB : BB (90:10 v/v) 33 (1300nm) 17 (1400nm) 90 Device Example 1A o-DCB : BB (90:10 v/v) 10 (1300nm) 5 (1400nm) 12 Device Example 2 TMB : BB (90:10 v/v) 33 (1100nm) 20 Comparison device 2 TMB : BB (90:10 v/v) 27 (1100nm) 11 Device Example 3A TMB:DMOB (95:5 v/v) 7 (1250nm) 10 Device Example 3B oDCB:1-ClNp (80:20) 10 (1250nm) 40 Comparison device 3A TMB:DMOB (95:5 v/v) 7 (1250nm) 4 Comparison device 3B oDCB:1-ClNp (80:20) 2.5 (1250nm) 2 Device Example 4A TMB : BB (90:10 v/v) 14 (1300nm) 3 (1400nm) 37 Device Example 4B o-DCB : BB (90:10 v/v) 20 (1300nm) 27 (1400nm) 103 Comparison device 4 TMB : BB (90:10 v/v) 7 (1300nm) 58 o-DCB: o-dichlorobenzene BB: butyl benzoate TMB: 1,3,4-trimethylbenzene DMOB: 1,2-dimethoxybenzene 1-ClNp: 1-chloronaphthalene

Modeling The HOMO and LUMO energy levels of the NFA of formula (I) containing the group of formula (III) and the comparative NFA without the group of formula (III) were modeled. The results are shown in Table 4, where S1f corresponds to the oscillator intensity (predicted absorption intensity) shifted from S1 and Eopt is the modeled optical gap.

Compared with NFAs with relatively electron-accepting end groups, NFAs with electron-accepting end groups of formula (III) have smaller modeled band gaps and longer wavelength modeled optical gaps. Table 4 Structure HOMO /eV LUMO /eV Eg /nm S1f Eopt/nm Comparison with model compound 1 -5.28 -3.84 864 2.95 923 Comparison with model compound 2 -5.22 -3.80 860 3.54 922 Comparison with model compound 3 -5.66 -4.06 776 2.56 823 Comparison with model compound 4 -5.27 -3.56 732 2.65 780 Model compound 1 -5.37 -4.10 979 3.26 1030 Model compound 2 -5.32 -4.02 952 3.02 1017 Model compound 3 -5.06 -3.67 894 3.22 952 Model compound 4 -5.11 -3.75 913 3.29 972 Model compound 5 -5.10 -3.74 911 3.33 974 Model compound 6 -5.36 -4.15 1021 3.17 1090 Model compound 7 -5.11 -4.13 1265 3.48 1263 Model compound 8 -5.01 -4.09 1349 2.61 1434 Model compound 9 -5.38 -3.85 811 2.81 858 Model compound 10 -5.73 -4.31 875 2.81 920

101: Substrate 103: Cathode 105: Body heterojunction layer 107: Anode

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

FIG. 1 illustrates an organic light responsive device according to some embodiments;

FIG2 is a graph showing the wavelength versus extinction coefficient of a toluene solution of Example Compound 1 and a toluene solution of Comparative Compound 1;

FIG3 is a graph showing the wavelength phase of the film of Compound Example 1 and the film of Comparative Compound 1 compared to the normalized absorbance;

FIG4 is a graph of external quantum efficiency (EQE) versus wavelength for OPD device Example 1 in which the only acceptor is Compound Example 1 and OPD device Example 2 in which the acceptors are Compound Example 1 and PCBM;

FIG5 is a graph of external quantum efficiency (EQE) versus wavelength for OPD Comparison Device 2 containing Comparison Compound 1 and PCBM; and

FIG. 6 shows the dark current of the OPD device containing Compound Example 1 and the OPD device containing Comparative Compound 1 under a reverse bias voltage of -3V.

The drawings are not drawn to scale and have various viewpoints and perspectives. The drawings are some embodiments and examples. In addition, for the purpose of discussing some embodiments of the disclosed technology, some components and/or operations may be separated into different blocks or combined into a single block. In addition, although the technology is suitable for various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and described in detail below. However, it is not desired to limit the technology to the specific embodiments described. Instead, it is desired that the technology cover all modifications, equivalents and alternatives that fall within the scope of the technology as defined by the attached application scope.

Claims (15)

A compound of formula (I) or (II): A ¹ - (B ¹ )x ¹ - (D ¹ )y ¹ - (B ¹ )x ² - A ¹ (I) A ¹ - (B ² )x ⁵ - (D ² )y ² - (B ³ )x ³ - A ² - (B ³ )x ⁴ - (D ³ )y ³ - (B ² )x ⁶ - A ¹ (II) wherein: A ² is a divalent heteroaromatic electron accepting group; D ¹ , D ² and D ³ are independently electron donating groups at each occurrence; B ¹ , B ² and B ³ are independently bridging groups at each occurrence; x ¹ to x ⁶ are independently 0, 1, 2 or 3; y ¹ , y ² and y ³ are independently at least 1; ^A1 is independently at each occurrence a group of formula (III), (III) wherein: each R ¹ is independently a substituent; R ² is H or a substituent; each R ³ is independently H or a substituent; J is C=O, C=S, NR ¹¹ or CR ¹² R ¹³ , wherein R ¹¹ is CN or COOR ⁴⁰ , and R ⁴⁰ is H or a substituent and R ¹² and R ¹³ are each independently CN, CF ₃ or COOR ⁴⁰ ; and each Z ¹ is N and each Z ² is CR ⁴ , or each Z ¹ is CR ⁴ and each Z ² is N, wherein each R ⁴ is independently H or a substituent. The compound of claim 1, wherein each Z ¹ is N and each Z ² is CR ⁴ . The compound of claim 1, wherein each Z ² is N and each Z ¹ is CR ⁴ . The compound of any one of claims 1 to 3, wherein each R ¹ is independently selected from CN, CF ₃ and COOR ⁴⁰ , wherein R ⁴⁰ at each occurrence is H or a substituent. The compound of any one of claims 1 to 3, wherein each R ³ is an electron withdrawing group. The compound of claim 5, wherein the electron-withdrawing group is selected from Cl, F, CN, C _{1 - 12} fluoroalkyl and COOR ¹⁵ , wherein R ¹⁵ is C _{1 - 20} alkyl. The compound of any one of claims 1 to 3, wherein each R ⁴ is independently selected from H or an electron withdrawing group. A composition comprises an electron donating material and an electron accepting material, wherein the electron accepting material is a compound as claimed in any one of the preceding claims. An organic electronic device comprises an active layer comprising the compound or composition of any of the preceding claims. An organic electronic device as claimed in claim 9, wherein the organic electronic device is an organic photo-responsive device, the organic photo-responsive device comprises a bulk heterojunction layer disposed between an anode and a cathode, and wherein the bulk heterojunction layer comprises the composition as claimed in claim 8. An organic electronic device as claimed in claim 10, wherein the organic light responsive device is an organic light detector. A photo sensor comprises a light source and an organic photodetector as claimed in claim 11, wherein the organic photodetector is configured to detect light emitted from the light source. A photosensor as claimed in claim 12, wherein the light source emits light having a peak wavelength greater than 900 nm. A formulation comprising the compound or composition of any one of claims 1 to 8 dissolved or dispersed in one or more solvents. A method of forming an organic electronic device as claimed in any one of claims 9 to 11, wherein the formation of the active layer comprises depositing the formulation of claim 14 onto a surface and evaporating the one or more solvents.