WO2024115332A1

WO2024115332A1 - Compounds for organic electronic devices

Info

Publication number: WO2024115332A1
Application number: PCT/EP2023/083064
Authority: WO
Inventors: Helen BENJAMIN; Michal MACIEJCZYK
Original assignee: Cambridge Display Technology Limited; Sumitomo Chemical Co., Ltd
Priority date: 2022-11-28
Filing date: 2023-11-24
Publication date: 2024-06-06
Also published as: GB2624714A; GB202217854D0

Abstract

A compound of formula (I) or (II): A¹ − (B¹)x¹ − (D¹)y¹ − (B¹)x² − A¹(I), A¹ − (B²)x⁵ − (D²)y²− (B³)x³ − A²− (B³)x⁴ − (D³)y³ − (B²)x⁶ − A¹(II). A² is a divalent heteroaromatic electron-accepting group; D¹, D² and D³ independently in each occurrence is an electron-donating group; B¹, B², and B³ independently in each occurrence is a bridging group; x ¹− x⁶ are each independently 0, 1, 2 or 3; y ¹, y² and y³ are each independently at least 1; and A¹ in each occurrence is independently a group of formula (III) wherein: R¹⁰ is H or a substituent; G is SO or SO₂; Ar^A is optionally present; and each of R^A, R^B, R^C and R^D is independently H or a substituent with the proviso that at least one of least one of R^A, R^B, R^C and R^D is CN in the case where Ar^A is absent.

Description

COMPOUNDS FOR ORGANIC ELECTRONIC DEVICES

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 (OPD) may contain a photoactive layer of a blend of an electrondonating material and an electron- accepting material between an anode and a cathode. Known electron-accepting materials include fullerenes and non-fullerene acceptors (NFAs).

WO 2018/065350A1 discloses the preparation of organic semiconductor compounds for the preparation of organic electronic (OE) devices, perovskite-based solar cell (PSC) devices, organic photodetectors (OPD), organic field effect transistors (OFET) and organic light emitting diodes (OLED).

WO 2018/065352A1 discloses an OPD having a photoactive layer that contains a small molecule acceptor which does not contain a fullerene moiety and a conjugated copolymer electron donor having donor and acceptor units.

WO 2018/232358A1 discloses visibly transparent photovoltaic devices that make use of transparent electrodes and visibly transparent photoactive compounds.

WO 2020/052194A1 discloses an organic solar battery device comprising a fused ring benzothiadiazole NFA material.

CN109232604A discloses an NFA material and organic solar battery.

Cao et al, “End-cap Group Engineering of a Small Molecule Non-Fullerene Acceptor: The Influence of Benzo thiophene Dioxide”

ACS Appl. Energy Mater. 2018, 1, 12, 7146-7152, discloses end-cap group engineering of nonfullerene acceptor ITBC.

Song et al, “Sulfonyl-based non-fullerene electron acceptor-assisted grain boundary passivation for efficient and stable perovskite solar cells”, J. Mater. Chem. A, 2019,7, 19881- 19888, discloses NFA-assisted grain boundary passivation. Tao et al, “Highly Efficient Nonfullerene Acceptor with Sulfonyl-Based Ending Groups”, ACS Appl. Mater. Interfaces 2020, 12, 44, 49659-49665 discloses an acceptor-donor-acceptor (A- D-A) type NFA which has a 2,1,3-benzothiadiazole-based core and sulfonyl-based ending groups.

Deng et al, “Fused ring non-fullerene acceptors with benzothiophene dioxide end groups and their side chain effect investigations”, Dyes and Pigments, 180,2020,108452,0143-7208, discloses fused ring NFA and their side chain effect investigations.

Khalid et al, “Exploration of the interesting photovoltaic behavior of the fused benzothiophene dioxide moiety as a core donor with modification in acceptors for high-efficacy organic solar cells”, RSC Adv., 2022,12, 29010-29021 discloses benzothiophene-based non-fullerene acceptors for organic solar cells.

SUMMARY

The present disclosure provides a compound of formula (I) or (II):

A¹ - (BV - (D')y¹ - (B^x)x² - A¹

(I)

A¹ - (B²)X⁵ - (D²)y² - (B³)X³- A² - (B³)x⁴ - (D³)y³ - (B²)x⁶ - A¹

(II) wherein:

A² is a divalent heteroaromatic electron- accepting group;

D¹, D² and D³ independently in each occurrence is an electron-donating group;

B¹, 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;

A¹ in each occurrence is independently a group of formula (III):

wherein:

R¹⁰ is H or a substituent;

G is SO or SO₂;

Ar^A is optionally present; and each of R^A, R^B, R^c and R^D is independently H or a substituent with the proviso that at least one of least one of R^A, R^B, R^c and R^D is CN in the case where Ar^A is absent.

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.

Optionally, the organic electronic device is an organic photoresponsive device comprising a photoactive layer disposed between an anode and a cathode and wherein the photoactive layer comprises a compound 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 material.

Optionally, the organic photoresponsive device is an organic photodetector.

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

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

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 photoresponsive 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. 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, 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 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, 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. 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 formulae (I) and (II) are

(II)

A¹ is a monovalent electron- accepting group.

A² is a divalent heteroaromatic electron- accepting group.

D¹, D² and D³ independently in each occurrence is an electron-donating group.

B¹, B², and B³ independently in each occurrence is a bridging group. x¹ - x⁶ 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^xand A² 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 D¹, D² or D³, preferably at least 1 eV deeper. The LUMO levels of electronaccepting groups and electron-donating groups may be as determined by modelling the LUMO level of these groups, in which 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).

Electron-Accepting Groups A¹

A¹ of formula (I) or formula (II) may be the same or different, preferably the same. A¹ is bound directly to D¹ of formula (I) or D² or D³ of formula (II) or, if present to B¹ of formula (I) or B² of formula (II).

A¹ is a group of formula (III):

wherein:

G is SO or SO2, preferably SO2;

R¹⁰ is H or a substituent, preferably H or a substituent selected from the group consisting of Ci- 12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, 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 Ci-12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, COO or CO.

Optionally, each R⁶ of any NR⁶ described herein is independently selected from H; Ci-20 alkyl wherein one or more non-adjacent C atoms other than the C atom bound to N may be replaced with O, S, NR¹¹, 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 Ci-12 alkyl groups wherein one or more non-adjacent C atoms of the alkyl may be replaced with O, S, NR¹¹, COO or CO and one or more H atoms of the alkyl may be replaced with F wherein R¹¹ is H or a Ci-2ohydrocarbyl group.

A Ci -20 hydrocarbyl group as described anywhere is preferably selected from Ci-20 alkyl; unsubstituted phenyl; and phenyl substituted with one or more Ci-12 alkyl groups.

In some embodiments, Ar^A is present. In these embodiments, each of R^A, R^B, R^c and R^D is optionally and independently selected from H or a substituent selected from C 1-20 hydrocarbyl and an electron withdrawing group. Exemplary electron-withdrawing groups are Cl, F, CN, Ci-nfluoroalkyl and COOR¹⁵ wherein R¹⁵ is a C 1-20 hydrocarbyl group. Preferably, at least one of R^A, R^B, R^C and R^D is CN. Preferably, R^B and R^c are both electron-withdrawing groups, preferably both CN. Preferably, R^A and R^D are each H.

The Ci -20 hydrocarbyl group R^A, R^B, R^c or R^D may be selected from Ci-20 alkyl; unsubstituted phenyl; and phenyl substituted with one or more Ci-12 alkyl groups.

In some embodiments, Ar^A is absent. According to these embodiments, at least one of R^A, R^B, R^c and R^D is CN. Non-CN groups R^A, R^B, R^c and R^D of these embodiments are preferably selected from H or a substituent selected from C 1-20 hydrocarbyl and an electron withdrawing group other than CN, for example Cl, F, Ci-12 fluoroalkyl and COOR¹⁵ wherein R¹⁵ is a Ci-20 hydrocarbyl group. Preferably, R^B and R^c are both CN. Preferably, R^A and R^D are each H.

Acceptor Unit A²

A² is preferably a fused heteroaromatic group comprising at least 2 fused rings, preferably at least 3 fused rings.

In some embodiments, A² of formula (II) is a group of formula (VIII):

wherein:

Ar¹ is an aromatic or heteroaromatic group; and

Y is O, S, NR⁶ or R⁷-C=C-R⁷ wherein R⁷ in each occurrence is independently H or a substituent wherein two substituents R⁷ may be linked to form a monocyclic or polycyclic ring; and R⁶ is H or a substituent.

In the case where A² is a group of formula (VIII), Ar¹ may be a monocyclic or polycyclic heteroaromatic group which is unsubstituted or substituted with one or more R⁹ groups wherein R⁹ in each occurrence is independently a substituent.

Preferred R⁹ groups are selected from

F;

CN;

NO₂;

C1-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR¹⁷ wherein R¹⁷ is a Ci-nhydrocarbyl, 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

wherein Z⁴⁰, Z⁴¹, Z⁴² and Z⁴³ are each independently CR¹³ or N wherein R¹³ in each occurrence is H or a substituent, preferably a Ci-2ohydrocarbyl group; Y⁴⁰ and Y⁴¹ are each independently O, S, NX⁷¹ wherein X⁷¹ is CN or COOR⁴⁰; or CX⁶⁰X⁶¹ wherein X⁶⁰ and X⁶¹ is independently CN, CF3 or COOR⁴⁰; W⁴⁰ and W⁴¹ are each independently O, S, NX⁷¹ or CX⁶⁰X⁶¹ wherein X⁶⁰ and X⁶¹ is independently CN, CF3 or COOR⁴⁰; and R⁴⁰ in each occurrence is H or a substituent, preferably H or a Ci-20 hydrocarbyl group. Exemplary substituents of an aromatic or heteroaromatic group R⁹ are F, CN, NO2, and Ci-12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F.

R¹⁷ as described anywhere herein may be, for example, Ci-12 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-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 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 described anywhere herein is preferably a non-terminal C atom, and the resultant substituent group is preferably non-ionic. Exemplary monocyclic heteroaromatic groups Ar¹ 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 Ar¹ are groups of formula (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 as described above.

X³, X⁴, X⁵ and X⁶ are each independently selected from N and CR¹⁰ with the proviso that at least one of X³, X⁴, X⁵ and X⁶ is CR¹⁰.

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 in each occurrence is an electronwithdrawing group.

Preferably, each R⁵ is CN, COOR⁴⁰; or CX⁶⁰X⁶¹ wherein X⁶⁰ and X⁶¹ is independently CN, CF3 or COOR⁴⁰ and R⁴⁰ in each occurrence is H or a substituent, preferably H or a Ci-₂ohydrocarbyl group.

A² groups of formula (VIII) are preferably selected from groups of formulae (Villa) and (Vlllb):

(Villa) (Vlllb)

For compounds of formula (Vlllb), the two R⁷ groups may or may not be linked.

Preferably, when the two R⁷ groups are not linked each R⁷ is independently selected from H; F; CN; NO₂; Ci -20 alkyl wherein one or more non- adjacent C atoms may be replaced with O, S, NR⁶, CO, COO, NR⁶, PR⁶, or Si(R¹⁰)₂ wherein R¹⁰ and R⁶ are as described above and one or more H atoms may be replaced with F; and aryl or heteroaryl, preferably phenyl, which may be unsubstituted or substituted with one or more substituents. Substituents of the aryl or heteroaryl group may be selected from one or more of F; CN; NO₂; and Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, CO, COO and one or more H atoms may be replaced with F.

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

(VIIIb-1) (VIIIb-2)

Ar² is an aromatic or heteroaromatic group, preferably benzene, which is unsubstituted or substituted with one or more substituents. Ar² may be unsubstituted or substituted with one or more substituents R² as described above.

X 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, R⁶ and R⁵ are as described above.

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

wherein Ak¹ is a Ci-20 alkyl group

Divalent electron-accepting groups A² other than formula (VIII) are optionally selected from formulae (IVa)-(IVk)

R²³ in each occurrence is a substituent, optionally Ci-12 alkyl wherein one or more non-adjacent C atoms other than the C atom attached to Z³ may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F.

R²⁵ in each occurrence is independently H; F; CN; NO2; Ci-12 alkyl wherein one or more non- adjacent C atoms may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F; an aromatic group, optionally phenyl, which is unsubstituted or substituted with one or more substituents selected from F and Ci-12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, COO or CO; or

wherein Z⁴⁰, Z⁴¹, Z⁴² and Z⁴³ are each independently CR¹³ or N wherein R¹³ in each occurrence is H or a substituent, preferably a Ci-2ohydrocarbyl group;

Y⁴⁰ and Y⁴¹ are each independently O, S, NX⁷¹ wherein X⁷¹ is CN or COOR⁴⁰; or CX⁶⁰X⁶¹ wherein X⁶⁰ and X⁶¹ is independently CN, CF3 or COOR⁴⁰;

W⁴⁰ and W⁴¹ are each independently O, S, NX⁷¹ wherein X⁷¹ is CN or COOR⁴⁰; or CX⁶⁰X⁶¹ wherein X⁶⁰ and X⁶¹ is independently CN, CF3 or COOR⁴⁰; and

R⁴⁰ in each occurrence is H or a substituent, preferably H or a Ci-20 hydrocarbyl group.

Z³ 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, T³ is benzo thiadiazole .

R¹² in each occurrence is a substituent, preferably a Ci-20 hydrocarbyl group.

Ar⁵ 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.

Bridging units

Bridging unit B¹ is preferably each selected from vinylene, arylene, heteroarylene, arylenevinylene and heteroarylenevinylene wherein the arylene and heteroarylene groups are monocyclic or bicyclic groups, each of which may be unsubstituted or substituted with one or more substituents.

Optionally, B¹ is selected from units of formulae (Via) - (VIo):

(Vim) (VIn) (VIo) wherein R⁵⁵ is H or a substituent; R⁸ in each occurrence is independently H or a substituent, preferably H or a substituent selected from F; CN; NO2; Ci-20 alkyl wherein one or more non- adjacent C atoms may be replaced with O, S, NR⁶, 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(R¹⁴)2 wherein R¹⁴ in each occurrence is a substituent, optionally a Ci-2ohydrocarbyl group. R⁸ groups of formulae (Via), (Vlb) and (Vic) may be linked to form a bicyclic ring which may be substituted with one or more substituents, optionally one or more substituents selected from F; CN; NO2; Ci -20 alkyl wherein one or more non- adjacent C atoms may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F.

R⁸ is preferably H, Ci-20 alkyl or Ci-19 alkoxy.

In compounds of formula (I), x¹ is preferably 0 or 1.

In compounds of formula (II), x³ and x⁴ are preferably 0 and x⁵ and x⁶ are preferably 0 or 1.

Electron-Donating Groups D¹, D² and D³

Electron-donating groups preferably are fused aromatic or heteroaromatic groups, more preferably fused heteroaromatic groups, containing three or more rings. Particularly preferred electron-donating groups comprise fused thiophene or furan rings, optionally fused rings 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 D¹, D² and D³ include groups of formulae (Vlla)-(VIIm):

wherein Y^A in each occurrence is independently O, S or NR⁵⁵; X^A is C or Si; Z^A in each occurrence is O, CO, S, NR⁵⁵ or C(R⁵⁴ ; R⁵¹, R⁵² R⁵⁴ and R⁵⁵ independently in each occurrence is H or a substituent; R⁵³ independently in each occurrence is a substituent; and Ar⁴ is an optionally substituted monocyclic or fused heteroaromatic group.

Optionally, R⁵¹ and R⁵² independently in each occurrence are selected from H; F; Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F; and an aromatic or heteroaromatic group Ar³ which is unsubstituted or substituted with one or more substituents.

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

Ar⁴ is preferably selected from optionally substituted oxadiazole, thiadiazole, triazole, and 1,4- diazine. In the case where Ar⁴ is 1,4-diazine, the 1,4-diazine may be fused to a further heterocyclic group, optionally a group selected from optionally substituted oxadiazole, thiadiazole, triazole, 1,4-diazine and succinimide.

The one or more substituents of Ar³, if present, may be selected from Ci-12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, 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:

H;

F; linear, branched or cyclic Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced by O, S, NR¹⁷, CO or COO wherein R¹⁷ is a C1-12 hydrocarbyl and one or more H atoms of the Ci-20 alkyl may be replaced with F; and 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 O, S, NR⁶, 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. Substituents of Ar⁷, if present, are preferably selected from F; Cl; NO2; CN; and Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, CO or COO and one or more H atoms may be replaced with F. Preferably, Ar⁷ is phenyl.

Preferably, each R⁵¹ is H.

Optionally, R⁵³ independently in each occurrence is selected from Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, 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 Ci-12 alkyl groups wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, COO or CO and one or more H atoms of the alkyl may be replaced with F.

Preferably, R⁵⁵ as described anywhere herein is H or Ci-3ohydrocarbyl group.

In a preferred embodiment, D¹ of the compound of formula (I) or D² and D³ of the compound of formula (II) is a group of formula (Vile). In a preferred embodiment of formula (Vile), Y^A is S and R⁵¹ is H.

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

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

In some embodiments, y¹ of formula (I) or at least one of y² and y³ of formula (II) is greater than 1. In these embodiments, the chain of D¹, D² or D³ groups, respectively, may be linked in any orientation.

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

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) or (II) 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.

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

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

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 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, polytriarylamine, poly(phenylene vinylene), poly(3-substituted thiophene), poly(3,4-bisubstituted thiophene), polyselenophene, poly(3-substituted selenophene), poly(3,4-bisubstituted selenophene), poly(bisthiophene), poly(terthiophene), poly(bisselenophene), poly(terselenophene), polythieno[2,3-b]thiophene, poly thieno [3, 2-b] thiophene, polybenzothiophene, polybenzo [1,2- b:4,5-b']dithiophene, polyisothianaphthene, poly(monosubstituted pyrrole), poly(3,4- bisubstituted pyrrole), poly-1, 3, 4-oxadiazoles, polyisothianaphthene, derivatives and copolymers thereof may be mentioned.

Preferred examples of donor polymers are copolymers of polyfluorenes and poly thiophenes, each of which may be substituted, and polymers comprising benzothiadiazole-based and thiophene-based repeating units, each of which may be substituted.

A particularly preferred donor polymer comprises a repeat unit of formula (X):

wherein Y^A, Z^A, R⁵¹ and R⁵⁴ are as described above.

Another particularly preferred donor polymer comprises repeat units of formula (XI):

wherein R¹⁸ and R¹⁹ are each independently selected from H; F; Ci-12 alkyl wherein one or more non-adjacent, non-terminal C atoms may be replaced with O, S, COO or CO and one or more H atoms of the alkyl may be replaced with F; or an aromatic or heteroaromatic group Ar⁶ which is unsubstituted or substituted with one or more substituents selected from F and Ci-12 alkyl wherein one or more non-adjacent, non-terminal C atoms may be replaced with O, S, COO or CO.

The donor polymer is preferably a donor-acceptor (DA) copolymer comprising a donor repeat unit, for example a repeat unit of formula (X) or (XI), and an acceptor repeat unit, for example divalent electron- accepting units A² as described herein provided as polymeric repeat units.

Organic Electronic Device

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

The bulk heterojunction layer comprises or consists of an electron-donating material and an electron-accepting compound of formula (I) or (II) as 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 of the 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, i.e. the electron-donating material has a shallower HOMO and LUMO that the corresponding HOMO and LUMO levels of the electron- accepting material. Preferably, the compound of formula (I) or (II) 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) or (II) is less than 1.4 eV.

Organic photoresponsive device

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 photoactive layer 105 disposed between the anode and the cathode. The organic photoresponsive device may be supported on a substrate 101, optionally a glass or plastic substrate.

In some embodiments, the photoactive layer is a bulk heterojunction layer. The bulk heterojunction layer contains an electron-donating compound and an electron- accepting compound of formula (I) or (II). The bulk heterojunction layer may consist of these materials or may comprise one or more further materials, for example one or more further electrondonating materials and / or one or more further electron- accepting compounds.

In some embodiments, the photoactive layer comprises or consists of an electron-accepting sub-layer comprising or consisting of a compound of formula (I) or (II) and an electrondonating sub-layer comprising or consisting of an electron-donating material.

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 photoactive layer. In some embodiments, both of the anode and 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 photoactive layer shown in Figure 1. In some embodiments, a hole-transporting layer is disposed between the anode and the photoactive layer. In some embodiments, an electrontransporting layer is disposed between the cathode and the photoactive layer. In some embodiments, a work function modification layer is disposed between the photoactive layer and the anode, and/or between the photoactive 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 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 in the range of 0.5 micron² - 900 micron².

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.

Fullerene

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

In some embodiments, an electron-accepting sub-layer or a bulk heterojuction layer contains a compound of formula (I) or (II) and one or more further electron- accepting materials. Preferred further electron-accepting materials are fullerenes. The compound of formula (I) or (II) : fullerene acceptor weight ratio may be in the range of about 1 : 0.1 - 1 : 1, preferably in the range of about 1 : 0.1 - 1 : 0.5.

Fullerenes may be selected from, without limitation, Ceo, C70, C76, C78 and Cs4 fullerenes or a derivative thereof, including, without limitation, PCBM-type fullerene derivatives including phenyl-Cei-butyric acid methyl ester (CeoPCBM), TCBM-type fullerene derivatives (e.g. tolyl- Cei-butyric acid methyl ester (CeoTCBM)), and ThCBM-type fullerene derivatives (e.g. thienyl-Cei -butyric acid methyl ester (CeoThCBM).

Fullerene derivatives may have formula (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):

wherein R²⁰-R³² 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 Ci-20 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, 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-12 alkyl wherein one or more non-adjacent C atoms may be replaced with O, S, NR⁶, CO or COO and one or more H atoms may be replaced with F.

Formulations

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

Preferably, the photoactive layer comprising the compound of formula (I) or (II) 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, rollcoating, spray coating, doctor blade coating, wire bar coating, slit coating, ink jet printing, screen printing, gravure printing and flexographic 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, Ci-io 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, optionally toluene, xylenes, trimethylbenzenes, tetramethylbenzenes, anisole, 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 substituents 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 Ci-io 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 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, defoaming 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 one or more of a voltage source for applying a reverse bias to the device; a device configured to measure photocurrent; and an amplifier configured to amplify an output signal of the OPD. 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. The present inventors have found that compounds of formula (I) or (II) as described herein may absorb at wavelengths of 900 nm or more or 1000 nm or more, making them suitable for use in organic photodetectors for detection of near-infrared emission. 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.

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 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 ID 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

The acceptor groups of Compound Example 1 may be prepared according to the following reaction scheme:

Step 1 :

W02001081340 A2

Journal of Organic Chemistry, 83(22), 13834-13846; 2018

Step 2

Dyes and Pigments, 2020, vol 180, 108452

The acceptor group may be reacted to form Compound Example 1 following the method disclosed in WO 2022/129137, the contents of which are incorporated herein by reference.

Modelling data

Energy levels of Model Compound Example 1 and Model Comparative Compounds 1 and 2 were modelled using Gaussian09 software available from Gaussian using Gaussian09 with B3LYP (functional). Results are set out in Table 1 in which in which Slf corresponds to oscillator strength of the transition from SI (predicting absorption intensity) and Eopt is the modelled optical gap. As set out in Table 1, Model Compound Example 1 has a deeper LUMO, smaller band gap and longer absorbance wavelength than Model Comparative Compounds 1 and 2.

Model Compound Structure:

Table 1

Claims

CLAIMS A compound of formula (I) or (II):

A¹ - (BV - (D')y¹ - (B^x)x² - A¹

(I)

(II) wherein:

A² is a divalent heteroaromatic electron- accepting group;

B¹, B², and B³ independently in each occurrence is a bridging group; x¹ - x⁶ are each independently 0, 1, 2 or 3; y¹, y² and y³ are each independently at least 1.

A¹ in each occurrence is independently a group of formula (III):

wherein:

R¹⁰ is H or a substituent;

G is SO or SO₂;

Ar^A is optionally present; and each of R^A, R^B, R^c and R^D is independently H or a substituent with the proviso that at least one of least one of R^A, R^B, R^c and R^D is CN in the case where Ar^A is absent. A compound according to claim 1 Ar^A is present and wherein at least one of R^A, R^B, R^c and R^D is an electron withdrawing group. A compound according to claim 2 wherein the electron withdrawing group is selected from Cl, F, CN, Ci -12 fluoroalkyl and COOR¹⁵ wherein R¹⁵ is a Ci-2ohydrocarbyl group. A compound according to claim 3 wherein the electron withdrawing group is CN. A compound according to claim 1 wherein Ar^A is absent. A compound according to any preceding claim wherein R^A and R^D is H and R^B and R^c is CN. A compound according to any one of the preceding claims wherein the compound is a compound of formula (I) and D¹ is a group of formula (Vile):

wherein Y^A in each occurrence is independently O, S or NR⁵⁵; R⁵¹ and R⁵⁵ independently in each occurrence is H or a substituent; and R⁵³ independently in each occurrence is a substituent. A compound according to claim 7 wherein Y^A is S. 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. An organic electronic device comprising an active layer comprising a compound or composition according to any one of the preceding claims. An organic electronic device according to claim 10 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 1-9 disposed between the anode and cathode. The organic electronic device according to claim 11 wherein the photoactive layer is a bulk heterojunction layer comprising a composition according to claim 9. An organic electronic device according to claim 11 or 12 wherein the organic photoresponsive device is an organic photodetector. A photosensor comprising a light source and an organic photodetector according to claim 13 wherein the organic photodetector is configured to detect light emitted from the light source. The photosensor according to claim 14, wherein the light source emits light having a peak wavelength of greater than 900 nm. A formulation comprising a compound or composition according to any one of claims 1 to 9 dissolved or dispersed in one or more solvents. A method of forming an organic electronic device according to any one of claims 11-13 wherein formation of the active layer comprises deposition of a formulation according to claim 16 onto a surface and evaporation of the one or more solvents.