WO2016078744A1 - Semiconducting mixtures - Google Patents

Abstract

The invention relates to novel semiconducting mixtures comprising a conjugated polymer and a substituted fullerene, to their use in organic electronic (OE) devices, especially organic photovoltaic (OPV) devices and organic photodetectors (OPD), and to OE, OPV and OPD devices comprising these mixtures.

Description

Semiconducting Mixtures

Technical Field The invention relates to novel semiconducting mixtures comprising a conjugated polymer and a substituted fullerene, to their use in organic electronic (OE) devices, especially organic photovoltaic (OPV) devices and organic photodetectors (OPD), and to OE, OPV and OPD devices comprising these mixtures.

Background

The photoactive layer in an organic photovoltaic (OPV) or an organic photodetector (OPD) device is composed of at least two components, a p- type semiconductor (or electron donor), such as a polymer, an oligomer or a defined molecular unit as first component, and a n-type semiconductor (or electron acceptor) such as a fullerene, substituted fullerene, graphene, metal oxide, or quantum dots as second component. In recent years, the stability of OPV devices has been investigated. The interactions which take place during OPV operation are complicated which generates many pathways for OPV device degradation.

A promising type of OPV device is the bulk heteroj unction (BHJ) OPV, wherein the p-type and the n-type semiconductor are mixed to form a blend. The p-type and n-type semiconductor in BHJ OPV devices should be selected such that they enable both effective charge generation and the creation of well formed and stable bulk heterojunctions.

However, the properties of donor-acceptor blends hitherto available for BHJ OPV devices, such as solubility, light stability, power conversion efficiency and thermal stability limit their broad commercial application.

Thus there is still a need for improved combinations of p-type and n-type semiconductors which are suitable for use in OPV devices, and in particular in BHJ OPV devices, which show good structural organization and film-forming properties, exhibit good electronic properties, especially high charge carrier mobility, a good processability, a high solubility in organic solvents, and high light and thermal stability.

It was an aim of the present invention to provide a combination of a p-type and n-type semiconductor which provides one or more of the above- mentioned advantageous properties. Another aim of the invention was to extend the pool of p-type/n-type semiconductor combinations available to the expert. Other aims of the present invention are immediately evident to the expert from the following detailed description.

The inventors of the present invention have found that one or more of the above aims can be achieved by providing a semiconducting mixture as disclosed and claimed hereinafter. Summary

The invention relates to a mixture comprising a conjugated polymer comprising one or more units of formula 1 and one or more units of formula 2

and a substituted fullerene of formula F

wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings

H, straight-chain or branched alkyl with 1 to 30 C atoms, in which one or more Chb groups are optionally replaced by - 0-, -S-, -C(O)-, -C(S)-, -C(0)-0-, -O-C(O)-, -NR°- - SiR°R⁰⁰-, -CF2-, -CHR°=CR⁰⁰-, -CY¹=CY²- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, CI or CN, a fullerene composed of n carbon atoms, optionally with one or more atoms trapped inside, an integer > 1 or a non-integer > 1 , an alkyl group with 7 to 20 C atoms, which is straight- chain or branched, and in which one or more Chb groups are optionally replaced by -0-, -S-, -C(=O)-, -C(=S)-, - C(=O)-0-, -0-C(=0)-, -NR⁰-, -C(=O)-NR⁰-, -NR°-C(=0)-, - SiR°R⁰⁰-, -CF2-, -CR°=CR⁰⁰-, -CR°=N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more atoms are optionally replaced by F, CI or CN,

Ar an aryl or heteroaryl group selected from formulae C1 to

C9, which is optionally substituted by one or more identical or different groups L

(C1) C3)

C5) (C6)

F, CI, -CN, or an alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group, each of which has 1 to 20 C atoms and is optionally fluorinated,

R° and R⁰⁰ H or alkyl with 1 to 12 C-atoms,

Y¹ and Y² H, F, CI or CN,

Ad an adduct, or a combination of adducts, appended to the fullerene Cn with any connectivity, m 0, an integer > 1 , or a non-integer > 0.

The invention further relates to a mixture as described above and below, further comprising one or more compounds which are selected from compounds having one or more of a semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting, photoactive and light emitting property. The invention further relates to a semiconducting, charge transport, electrically conducting, photoconducting, photoactive, thermoelectric or light emitting material, which comprises or consists of a mixture as described above and below.

The invention further relates to the use of a mixture as described above and below as semiconducting, charge transport, electrically conducting, photoconducting, photoactive, thermoelectric or light emitting material in an organic electronic (OE) device, or in a component of such an OE device, or in an assembly comprising such an OE device or such a component.

The invention further relates to a formulation comprising a mixture as described above and below, and further comprising one or more solvents, preferably selected from organic solvents, very preferably from non- chlorinated organic solvents, most preferably from non-halogenated organic solvents. The invention further relates to an OE device, or a component thereof, or an assembly comprising it, which is prepared using a formulation as described above and below.

The invention further relates to an OE device, or a component thereof, or an assembly comprising it, which comprises a mixture or a

semiconducting, charge transport, electrically conducting,

photoconducting, photoactive or light emitting material as described above and below. The OE device is preferably an optical, electrooptical, electronic, photoactive, electroluminescent or photoluminescent device.

The OE device includes, without limitation, organic field effect transistors (OFET), organic thin film transistors (OTFT), organic light emitting diodes (OLED), organic light emitting transistors (OLET), organic photovoltaic devices (OPV), organic photodetectors (OPD), organic solar cells, dye sensitized solar cells (DSSC), perovskite-based solar cells, laser diodes, Schottky diodes, photoconductors, photodetectors and thermoelectric devices. Preferred OE devices are OFETs, OTFTs, OPVs, OPDs and OLEDs, in particular bulk heterojunction (BHJ) OPVs or inverted BHJ OPVs.

Further preferred is the use of a mixture as described above and below as dye in a DSSC or perovskite-based solar cell comprising a mixture as described above and below.

The components of the above OE devices include, without limitation, charge injection layers, charge transport layers, interlayers, planarising layers, antistatic films, polymer electrolyte membranes (PEM), conducting substrates and conducting patterns.

The assemblies comprising such OE devices or components include, without limitation, integrated circuits (IC), radio frequency identification (RFID) tags or security markings or security devices containing them, flat panel displays or backlights thereof, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, biosensors and biochips.

In addition the mixture of the present invention can be used as electrode material in batteries and in components or devices for detecting and discriminating DNA sequences.

The invention further relates to a bulk heterojunction (BHJ) which comprises, or is being formed from, a mixture as described above and below, and to a BHJ OPV device, or an inverted BHJ OPV device, comprising such a bulk heterojunction.

Terms and Definitions As used herein, any reference to a formula, like for example "formula 1", is understood to be inclusive of any specific subformula of said formula as shown hereinafter.

As used herein, the term "fullerene" will be understood to mean a compound composed of an even number of carbon atoms, which form a cage-like fused-ring having a surface which comprises six-membered rings and five-membered rings, usually with twelve five-membered rings and the rest six-membered rings, optionally with one or more atoms trapped inside. The surface of the fullerene may also contain hetero atoms like B or N. As used herein, the term "endohedral fullerene" will be understood to mean a fullerene with one or more atoms trapped inside.

As used herein, the term "metallofullerene" will be understood to mean an endohedral fullerene wherein the atoms trapped inside are selected from metal atoms.

As used herein, the term "carbon based fullerene" will be understood to mean a fullerene without any atoms trapped inside, and wherein the surface is comprised only of carbon atoms.

As used herein, the term "polymer" will be understood to mean a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass (Pure Appl. Chem., 1996, 68, 2291). The term "oligomer" will be understood to mean a molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecular mass (Pure Appl. Chem., 1996, 68, 2291). In a preferred meaning as used herein present invention a polymer will be understood to mean a compound having > 1 , i.e. at least 2 repeat units, preferably > 5 repeat units, and an oligomer will be understood to mean a compound with > 1 and < 10, preferably < 5, repeat units.

Further, as used herein, the term "polymer" will be understood to mean a molecule that encompasses a backbone (also referred to as "main chain") of one or more distinct types of repeat units (the smallest constitutional unit of the molecule) and is inclusive of the commonly known terms

"oligomer", "copolymer", "homopolymer" and the like. Further, it will be understood that the term polymer is inclusive of, in addition to the polymer itself, residues from initiators, catalysts and other elements attendant to the synthesis of such a polymer, where such residues are understood as not being covalently incorporated thereto. Further, such residues and other elements, while normally removed during post polymerization purification processes, are typically mixed or co-mingled with the polymer such that they generally remain with the polymer when it is transferred between vessels or between solvents or dispersion media.

As used herein, in a formula showing a polymer or a repeat unit, an asterisk (*) will be understood to mean a chemical linkage to an adjacent unit or to a terminal group in the polymer backbone. In a ring, like for example a benzene or thiophene ring, an asterisk (^*) will be understood to mean a C atom that is fused to an adjacent ring.

As used herein, the terms "repeat unit", "repeating unit" and "monomeric unit" are used interchangeably and will be understood to mean the constitutional repeating unit (CRU), which is the smallest constitutional unit the repetition of which constitutes a regular macromolecule, a regular oligomer molecule, a regular block or a regular chain (Pure Appl. Chem., 1996, 68, 2291). As further used herein, the term "unit" will be understood to mean a structural unit which can be a repeating unit on its own, or can together with other units form a constitutional repeating unit.

As used herein, a "terminal group" will be understood to mean a group that terminates a polymer backbone. The expression "in terminal position in the backbone" will be understood to mean a divalent unit or repeat unit that is linked at one side to such a terminal group and at the other side to another repeat unit. Such terminal groups include endcap groups, or reactive groups that are attached to a monomer forming the polymer backbone which did not participate in the polymerisation reaction, like for example a group having the meaning of R³³ or R³⁴ as defined below. As used herein, the term "endcap group" will be understood to mean a group that is attached to, or replacing, a terminal group of the polymer backbone. The endcap group can be introduced into the polymer by an endcapping process. Endcapping can be carried out for example by reacting the terminal groups of the polymer backbone with a

monofunctional compound ("endcapper") like for example an alkyl- or arylhalide, an alkyl- or arylstannane or an alkyl- or arylboronate. The endcapper can be added for example after the polymerisation reaction. Alternatively the endcapper can be added in situ to the reaction mixture before or during the polymerisation reaction. In situ addition of an endcapper can also be used to terminate the polymerisation reaction and thus control the molecular weight of the forming polymer. Typical endcap groups are for example H, phenyl and lower alkyl. As used herein, the term "small molecule" will be understood to mean a monomeric compound which typically does not contain a reactive group by which it can be reacted to form a polymer, and which is designated to be used in monomeric form. In contrast thereto, the term "monomer" unless stated otherwise will be understood to mean a monomeric compound that carries one or more reactive functional groups by which it can be reacted to form a polymer.

As used herein, the terms "donor" or "donating" and "acceptor" or

"accepting" will be understood to mean an electron donor or electron acceptor, respectively. "Electron donor" will be understood to mean a chemical entity that donates electrons to another compound or another group of atoms of a compound. "Electron acceptor" will be understood to mean a chemical entity that accepts electrons transferred to it from another compound or another group of atoms of a compound. See also International Union of Pure and Applied Chemistry, Compendium of

Chemical Technology, Gold Book, Version 2.3.2, 19. August 2012, pages 477 and 480.

As used herein, the term "n-type" or "n-type semiconductor" will be understood to mean an extrinsic semiconductor in which the conduction electron density is in excess of the mobile hole density, and the term "p- type" or "p-type semiconductor" will be understood to mean an extrinsic semiconductor in which mobile hole density is in excess of the conduction electron density (see also, J. Thewlis, Concise Dictionary of Physics, Pergamon Press, Oxford, 1973).

As used herein, the term "leaving group" will be understood to mean an atom or group (which may be charged or uncharged) that becomes detached from an atom in what is considered to be the residual or main part of the molecule taking part in a specified reaction (see also Pure AppI. Chem., 1994, 66, 1134).

As used herein, the term "conjugated" will be understood to mean a compound (for example a polymer) that contains mainly C atoms with sp²- hybridisation (or optionally also sp-hybridisation), and wherein these C atoms may also be replaced by hetero atoms. In the simplest case this is for example a compound with alternating C-C single and double (or triple) bonds, but is also inclusive of compounds with aromatic units like for example 1 ,4-phenylene. The term "mainly" in this connection will be understood to mean that a compound with naturally (spontaneously) occurring defects, or with defects included by design, which may lead to interruption of the conjugation, is still regarded as a conjugated compound.

As used herein, unless stated otherwise the molecular weight is given as the number average molecular weight Mn or weight average molecular weight Mw, which is determined by gel permeation chromatography (GPC) against polystyrene standards in eluent solvents such as tetrahydrofuran, trichloromethane (TCM, chloroform), chlorobenzene or 1,2,4-trichloro- benzene. Unless stated otherwise, 1 ,2,4-trichlorobenzene is used as solvent. The degree of polymerization, also referred to as total number of repeat units, n, will be understood to mean the number average degree of polymerization given as n = Mn/Mu, wherein M_n is the number average molecular weight and Mu is the molecular weight of the single repeat unit, see J. M. G. Cowie, Polymers: Chemistry & Physics of Modern Materials, Blackie, Glasgow, 1991.

As used herein, the term "carbyl group" will be understood to mean any monovalent or multivalent organic moiety which comprises at least one carbon atom either without any non-carbon atoms (like for

example -C≡C-), or optionally combined with at least one non-carbon atom such as B, N, O, S, P, Si, Se, As, Te or Ge (for example carbonyl etc.).

As used herein, the term "hydrocarbyl group" will be understood to mean a carbyl group that does additionally contain one or more H atoms and optionally contains one or more hetero atoms like for example B, N, O, S, P, Si, Se, As, Te or Ge.

As used herein, the term "hetero atom" will be understood to mean an atom in an organic compound that is not a H- or C-atom, and preferably will be understood to mean B, N, O, S, P, Si, Se, As, Te or Ge. A carbyl or hydrocarbyl group comprising a chain of 3 or more C atoms may be straight-chain, branched and/or cyclic, and may include spiro-connected and/or fused rings.

Preferred carbyl and hydrocarbyl groups include alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy, each of which is optionally substituted and has 1 to 40, preferably 1 to 25, very preferably 1 to 18 C atoms, furthermore optionally substituted aryl or aryloxy having 6 to 40, preferably 6 to 25 C atoms, furthermore

alkylaryloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and

aryloxycarbonyloxy, each of which is optionally substituted and has 6 to 40, preferably 7 to 40 C atoms, wherein all these groups do optionally contain one or more hetero atoms, preferably selected from B, N, O, S, P, Si, Se, As, Te and Ge. Further preferred carbyl and hydrocarbyl group include for example: a Ci- C40 alkyl group, a C1-C40 fluoroalkyl group, a C1-C40 alkoxy or oxaalkyl group, a C2-C40 alkenyl group, a C2-C40 alkynyl group, a C3-C40 allyl group, a C4-C40 alkyldienyl group, a C4-C40 polyenyl group, a C2-C40 ketone group, a C2-C40 ester group, a C6-C18 aryl group, a C6-C40 alkylaryl group, a C6-C40 arylalkyl group, a C4-C40 cycloalkyl group, a C4-C40 cycloalkenyl group, and the like. Preferred among the foregoing groups are a C1-C20 alkyl group, a C1-C20 fluoroalkyl group, a C2-C20 alkenyl group, a C2 -C20 alkynyl group, a C3-C20 allyl group, a C4-C20 alkyldienyl group, a C2-C20 ketone group, a C2-C20 ester group, a C6-C12 aryl group, and a C4-C20 polyenyl group, respectively.

Also included are combinations of groups having carbon atoms and groups having hetero atoms, like e.g. an alkynyl group, preferably ethynyl, that is substituted with a silyl group, preferably a trialkylsilyl group. The carbyl or hydrocarbyl group may be an acyclic group or a cyclic group. Where the carbyl or hydrocarbyl group is an acyclic group, it may be straight-chain or branched. Where the carbyl or hydrocarbyl group is a cyclic group, it may be a non-aromatic carbocyclic or heterocyclic group, or an aryl or heteroaryl group.

A non-aromatic carbocyclic group as referred to above and below is saturated or unsaturated and preferably has 4 to 30 ring C atoms. A non- aromatic heterocyclic group as referred to above and below preferably has 4 to 30 ring C atoms, wherein one or more of the C ring atoms are optionally replaced by a hetero atom, preferably selected from N, O, S, Si and Se, or by a -S(O)- or -S(O)2- group. The non-aromatic carbo- and heterocyclic groups are mono- or polycyclic, may also contain fused rings, preferably contain 1 , 2, 3 or 4 fused or unfused rings, and are optionally substituted with one or more groups L, wherein

L is selected from halogen, -CN, -NC, -NCO, -NCS, -OCN, -SCN,

-C(=0)NR°R⁰⁰, -C(=0)X°, -C(=0)R°, -NH2, -NR°R⁰⁰, -SH, -SR°, -SOsH, -SO2R⁰, -OH, -NO2, -CF3, -SF5, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, and is preferably alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with 1 to 20 C atoms that is optionally fluorinated, X° is halogen, preferably F, CI or Br, and R°, R⁰⁰ have the meanings given above and below, and preferably denote H or alkyl with 1 to 12 C atoms. Preferred substituents L are selected from halogen, most preferably F, or alkyl, alkoxy, oxaalkyi, thioalkyi, fluoroalkyi and fluoroalkoxy with 1 to 12 C atoms, or alkenyl or alkynyl with 2 to 12 C atoms. Preferred non-aromatic carbocyclic or heterocyclic groups are

tetrahydrofuran, indane, pyran, pyrrolidine, piperidine, cyclopentane, cyclohexane, cycloheptane, cyclopentanone, cyclohexanone, dihydro- furan-2-one, tetrahydro-pyran-2-one and oxepan-2-one. An aryl group as referred to above and below preferably has 4 to 30 ring C atoms, is mono- or polycyclic and may also contain fused rings, preferably contains 1 , 2, 3 or 4 fused or unfused rings, and is optionally substituted with one or more groups L as defined above and below. A heteroaryl group as referred to above and below preferably has 4 to 30 ring C atoms, wherein one or more of the C ring atoms are replaced by a hetero atom, preferably selected from N, O, S, Si and Se, is mono- or polycyclic and may also contain fused rings, preferably contains 1, 2, 3 or 4 fused or unfused rings, and is optionally substituted with one or more groups L as defined above and below.

As used herein, "arylene" will be understood to mean a divalent aryl group, and "heteroarylene" will be understood to mean a divalent heteroaryl group, including all preferred meanings of aryl and heteroaryl as given above and below.

Preferred aryl and heteroaryl groups are phenyl in which, in addition, one or more CH groups may be replaced by N, naphthalene, thiophene, selenophene, thienothiophene, dithienothiophene, fluorene and oxazole, all of which can be unsubstituted, mono- or polysubstituted with L as defined above. Very preferred rings are selected from pyrrole, preferably N-pyrrole, furan, pyridine, preferably 2- or 3-pyridine, pyrimidine, pyridazine, pyrazine, triazole, tetrazole, pyrazole, imidazole, isothiazole, thiazole, thiadiazole, isoxazole, oxazole, oxadiazole, thiophene, preferably 2-thiophene, selenophene, preferably 2-selenophene, thieno[3,2- b]thiophene, thieno[2,3-b]thiophene, furo[3,2-b]furan, furo[2,3-b]furan, seleno[3,2-b]selenophene, seleno[2,3-b]selenophene, thieno[3,2- b]selenophene, thieno[3,2-b]furan, indole, isoindole, benzo[b]furan, benzo[b]thiophene, benzo[1 ,2-b;4,5-b']dithiophene, benzo[2,1-b;3,4- b']dithiophene, quinole, 2- methylquinole, isoquinole, quinoxaline, quinazoline, benzotriazole, benzimidazole, benzothiazole, benzisothiazole, benzisoxazole, benzoxadiazole, benzoxazole, benzothiadiazole, 4H- cyclopenta[2,1-b;3,4-b']dithiophene, 7H-3,4-dithia-7-sila- cyclopenta[a]pentalene, all of which can be unsubstituted, mono- or polysubstituted with L as defined above and below. Further examples of aryl and heteroaryl groups are those selected from the groups shown hereinafter.

An alkyl group or an alkoxy group, i.e., where the terminal CH2 group is replaced by -O-, can be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6, 7, 8, 12 or 16 carbon atoms and

accordingly is preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, dodecyl or hexadecyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, dodecoxy or hexadecoxy, furthermore methyl, nonyl, decyl, undecyl, tridecyl, tetradecyl, pentadecyl, nonoxy, decoxy, undecoxy, tridecoxy or tetradecoxy, for example.

An alkenyl group, i.e., wherein one or more CH2 groups are replaced by - CH=CH- can be straight-chain or branched. It is preferably straight-chain, has 2 to 10 C atoms and accordingly is preferably vinyl, prop-1-, or prop- 2-enyl, but-1-, 2- or but-3-enyl, pent-1-, 2-, 3- or pent-4-enyl, hex-1-, 2-, 3-,

4- or hex-5-enyl, hept-1-, 2-, 3-, 4-, 5- or hept-6-enyl, oct-1-, 2-, 3-, 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, dec-1-, 2-, 3-, 4-,

5- , 6-, 7-, 8- or dec-9-enyl. Especially preferred alkenyl groups are C2-C7-1 E-alkenyl, C4-C7-3E- alkenyl, C5-C7-4-alkenyl, C6-C7-5-alkenyl and C7-6-alkenyl, in particular C2-C7-I E-alkenyl, C4-C7-3E-alkenyl and Cs-C7-4-alkenyl. Examples for particularly preferred alkenyl groups are vinyl, 1 E-propenyl, 1 E-butenyl, 1 E-pentenyl, 1 E-hexenyl, 1 E-heptenyl, 3-butenyl, 3E-pentenyl,

3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5 C atoms are generally preferred.

An oxaalkyl group, i.e., where one Chb group is replaced by -O-, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-

(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7- oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-,7-, 8- or 9- oxadecyl, for example.

In an alkyl group wherein one Chb group is replaced by -O- and one Chb group is replaced by -C(O)-, these radicals are preferably neighboured. Accordingly these radicals together form a carbonyloxy group -C(O)-O- or an oxycarbonyl group -O-C(O)-. Preferably this group is straight-chain and has 2 to 6 C atoms. It is accordingly preferably acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl,

propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl,

2- acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetyloxypropyl,

3- propionyloxypropyl, 4-acetyloxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl,

methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl,

2- (propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl,

3- (ethoxycarbonyl)propyl, 4-(methoxycarbonyl)-butyl.

An alkyl group wherein two or more CH2 groups are replaced by -O- and/or -C(O)O- can be straight-chain or branched. It is preferably straight- chain and has 3 to 12 C atoms. Accordingly it is preferably bis-carboxy- methyl, 2,2-bis-carboxy-ethyl, 3,3-bis-carboxy-propyl, 4,4-bis-carboxy- butyl, 5,5-bis-carboxy-pentyl, 6,6-bis-carboxy-hexyl, 7,7-bis-carboxy- heptyl, 8,8-bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 0,10-bis-carboxy- decyl, bis-(methoxycarbonyl)-methyl, 2,2-bis-(methoxycarbonyl)-ethyl, 3,3-bis-(methoxycarbonyl)-propyl, 4,4-bis-(methoxycarbonyl)-butyl, 5,5-bis- (methoxycarbonyl)-pentyl, 6,6-bis-(methoxycarbonyl)-hexyl, 7,7-bis- (methoxycarbonyl)-heptyl, 8,8-bis-(methoxycarbonyl)-octyl, bis- (ethoxycarbonyl)-methyl, 2,2-bis-(ethoxycarbonyl)-ethyl, 3,3-bis- (ethoxycarbonyl)-propyl, 4,4-bis-(ethoxycarbonyl)-butyl, 5,5-bis- (ethoxycarbonyl)-hexyl.

A thioalkyi group, i.e., where one CH2 group is replaced by -S-, is preferably straight-chain thiomethyl (-SCH₃), 1-thioethyl (-SCH2CH3),

1-thiopropyl (= -SCH2CH2CH3), 1- (thiobutyl), l-(thiopentyl), l-(thiohexyl), l-(thioheptyl), l-(thiooctyl), l-(thiononyl), l-(thiodecyl), l-(thioundecyl) or

1- (thiododecyl), wherein preferably the CH2 group adjacent to the sp² hybridised vinyl carbon atom is replaced.

A fluoroalkyI group is perfluoroalkyi CiF2i+i , wherein i is an integer from 1 to 15, in particular CF3, C2F5, C3F7, C4F9, C5F11, C6F13, C7F15 or CsFi7, very preferably C6F13, or partially fluorinated alkyl, preferably with 1 to 15 C atoms, in particular ,1-difluoroalkyl, all of the aforementioned being straight-chain or branched.

Preferably "fluoroalkyl" means a partially fluorinated (i.e. not

perfluorinated) alkyl group. Alkyl, alkoxy, alkenyl, oxaalkyi, thioalkyi, carbonyl and carbonyloxy groups can be achiral or chiral groups. Particularly preferred chiral groups are

2- butyl (=1-methylpropyl), 2-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-butyloctyl, 2-hexyldecyl, 2-octyldodecyl, 2-propylpentyl, in particular 2-methylbutyl, 2-methylbutoxy, 2-methylpentoxy, 3-methyl- pentoxy, 2-ethyl-hexoxy, 2-butyloctoxyo, 2-hexyldecoxy, 2-octyldodecoxy,

1- methylhexoxy, 2-octyloxy, 2-oxa-3-methylbutyl, 3-oxa-4-methyl-pentyl, 4-methylhexyl, 2-hexyl, 2-octyl, 2-nonyl, 2-decyl, 2-dodecyl, 6-methoxy- octoxy, 6-methyloctoxy, 6-methyloctanoyloxy, 5-methylheptyloxy-carbonyl,

2- methylbutyryloxy, 3-methylvaleroyloxy, 4-methylhexanoyloxy, 2-chloro- propionyloxy, 2-chloro-3-methylbutyryloxy, 2-chloro-4-methyl-valeryl-oxy,

2-chloro-3-methylvaleryloxy, 2-methyl-3-oxapentyl, 2-methyl-3-oxa-hexyl, 1 -methoxypropyl-2-oxy, 1 -ethoxypropyl-2-oxy, 1 -propoxypropyl-2-oxy, 1-butoxypropyl-2-oxy, 2-fluorooctyloxy, 2-fluorodecyloxy, 1 ,1 ,1-trifluoro-2- octyloxy, 1 ,1 ,1-trifluoro-2-octyl, 2-fluoromethyloctyloxy for example. Very preferred are 2-ethylhexyl, 2-butyloctyl, 2-hexyldecyl, 2-octyldodecyl, 2-hexyl, 2-octyl, 2-octyloxy, 1 ,1 ,1 -trifluoro-2-hexyl, 1,1 ,1 -trifluoro-2-octyl and 1 ,1 , 1 -trifluoro-2-octyloxy.

Preferred achiral branched groups are isopropyl, isobutyl (=methylpropyl), isopentyl (=3-methylbutyl), tert. butyl, isopropoxy, 2-methyl-propoxy and 3- methylbutoxy.

In a preferred embodiment, the alkyl groups are independently of each other selected from primary, secondary or tertiary alkyl or alkoxy with 1 to 30 C atoms, wherein one or more H atoms are optionally replaced by F, or aryl, aryloxy, heteroaryl or heteroaryloxy that is optionally alkylated or alkoxylated and has 4 to 30 ring atoms. Very preferred groups of this type are selected from the group consisting of the following formulae

wherein "ALK" denotes optionally fluorinated, preferably linear, alkyl or alkoxy with 1 to 20, preferably 1 to 12 C-atoms, in case of tertiary groups very preferably 1 to 9 C atoms, and the dashed line denotes the link to the ring to which these groups are attached. Especially preferred among these groups are those wherein all ALK subgroups are identical.

As used herein, "halogen" or "hal" includes F, CI, Br or I, preferably F, CI or Br.

As used herein, -CO-, -C(=O)- and -C(O)- will be understood to

O

I I

carbonyl group, i.e. a group having the structure As used herein, C=CR¹R² will be understood to mean an ylidene group,

group having the structure

Above and below, Y¹ and N^ are independently of each other H, F, CI or CN.

Above and below, R° and R⁰⁰ are independently of each other H or an optionally substituted carbyl or hydrocarbyl group with 1 to 40 C atoms, and preferably denote H or alkyl with 1 to 12 C-atoms.

Detailed Description

The fullerenes of formula F demonstrate one or more of the following improved properties compared to previously disclosed fullerene

derivatives and mixtures for OPV/OPD application: i) The substituent R¹, which comprises an extended alkyl chain with 7 or more C atoms, and, if present, the substituent L which can possess any number of solubilising groups, enable greater light stability of the bulk heterojunction through mediation of the fullerene 2+2 Diels Alder dimerisation/oligomerisation reaction, as described, for example in Adv. Energy Mater. 2014, 4, 1300693 and ACS Nano 2014, 8 (2j, 1297-1308. ii) The substituent R¹ and, if present, the substituent L, enable greater stability towards light illumination of the bulk heterojunction through mediation of the fullerene crystallisation and/or phase separation kinetic, thus stabilising the initial equilibrium thermodynamics in the BHJ.

The substituent R¹ and, if present, the substituent L, enable greater thermal stability of the bulk heterojunction through mediation of the fullerene crystallisation and/or phase separation kinetic, thus

stabilising the initial equilibrium thermodynamics in the BHJ. iv) Electron accepting and/or donating unit(s) in positions Ar and R¹ of the fullerene reduce the fullerene band-gap and therefore the potential for improved light absorption. v) Additional fine-tuning of the electronic energies (HOMO/LUMO

levels) can be achieved by careful selection of the electron accepting and/or donating unit(s) in positions Ar and R¹ to increase the open circuit potential (Voc). vi) Additional fine-tuning of the electronic energies (HOMO/LUMO

levels) may result by careful selection of the electron accepting and/or donating unit(s) in positions Ar and R¹ to reduce the energy loss in the electron transfer process between the fullerene and the p- type material (i.e. polymer, oligomer, a define molecular unit) in the active layer. vii) The substituent R¹ and, if present, the substituent L, enable higher fullerene solubility in non-halogenated solvents due to the increased number of solubilising groups. viii) The substituent R¹ and, if present, the substituent L, increase the solubility and mutual compatibility (miscibility) of the fullerene with the polymer, minimizing heat and light induced phase separation which leads to an improvement in device operational stability.

The fullerene Cn in formula F and its subformulae may be composed of any number n of carbon atoms Preferably, in the compounds of formula F and its subformulae the number of carbon atoms n of which the fullerene Cn is composed is 60, 70, 76, 78, 82, 84, 90, 94 or 96, very preferably 60 or 70.

The mixture according to the present invention may also comprise two or more compounds of formula F which are differing in their number n of carbon atoms forming the fullerene. The mixture according to the present invention may also comprise two or more compounds of formula F which are differing in the structure and/or the number of carbon atoms of their substituent R¹. The mixture according to the present invention may also comprise two or more compounds of formula F which are differing in the structure of their substituent Ar.

Thus, in a further preferred embodiment of the present invention the fullerene mixture comprises a C60 fullerene and a higher fullerene, which is preferably selected from C70, C76, C78, C82, C84, C90, C94 or C96, and is very preferably C70, wherein optionally the C60 fullerene and the higher fullerene differ in at least one of

- the structure and/or number of carbon atoms of their substituent R , - the structure of their substituents Ar.

In a further preferred embodiment of the present invention the fullerene mixture comprises two or more fullerenes, which are preferably selected from C70, C76, C78, C82, C84, C90, C94 or C96, and are very preferably C60 or C70, wherein the two or more fullerenes differ in at least one of

- the structure and/or the number of carbon atoms of their substituent R¹,

- the structure of their substituent Ar.

The fullerene Cn in formula F and its subformulae is preferably selected from carbon based fullerenes, endohedral fullerenes, or mixtures thereof, very preferably from carbon based fullerenes.

Suitable and preferred carbon based fullerenes include, without limitation, (C60-ih)[5,6]fullerene, (C70-D5h)[5,6]fullerene, (C76-D2*)[5,6]fullerene, (Cs4- D2*)[5,6]fullerene, (C84-D2d)[5,6]fullerene, or a mixture of two or more of the aforementioned carbon based fullerenes.

The endohedral fullerenes are preferably metallofullerenes. Suitable and preferred metallofullerenes include, without limitation, La@C6o, La@Cs2, Y@C82, Sc3N@C8o, Y3N@C8o, Sc3C2@Ceo or a mixture of two or more of the aforementioned metallofullerenes. In the compound of formula F, the adduct -C(Ar)(R¹)- is preferably appended to the fullerene C_n by a [6,6]-bond and/or [5,6]-bond. Preferably the compound of formula F the adduct -C(Ar)(R¹)- is appended to the fullerene Cn by a [6,6]-bond, to form a [6,6]-Aryl-methanofullerene.

In case Cn is a less symmetric fullerene, like for example C70, the compound of formula F may also comprise a mixture of regioisomers in which the adduct -C(Ar)(R¹)- is appended to different bonds of the fullerene, as disclosed for example in C. Thilgen and F. Diederich, Top. Curr. Chem. 1999, 199, 135-171.

The compounds of formula F may also undergo fullerene 2+2 Diels Alder dimerisation/oligomerisation reaction, as described, for example in Adv. Energy Mater. 2014, 4, 1300693 and ACS Nano 2014, 8 (2), 1297-1308.

In the compounds of formula F and its subformulae, o preferably denotes 1 , 2, 3 or 4, very preferably 1 or 2. In another preferred embodiment, o is a non-integer > 1 like 1.5.

In the compounds of formula F and its subformulae, R¹ preferably denotes alkyl with 7 to 20, preferably 7 to 15, C atoms, in which one or more Chb groups are optionally replaced by -0-, -C(O)-, -C(0)-0- or -O-C(O)-, and in which one or more H atoms are optionally replaced by F.

Very preferably R¹ is selected from the following formulae:

R2

wherein the individual radicals have independently of each other the following meanings a, b 0 or an integer from 1 to 15, with a+b >5, c, d, e 0 or an integer from 1 to 15, with c+d+e >4, f an integer from 6 to 15, g 0 or an integer from 1 to 15,

R¹¹ straight-chain or branched alkyl with 5 to 15 C atoms wherein one or more H atoms are optionally replaced by F, or, in case g≥ 5, R¹¹ may also denote H, F, CN or alkyl with 1 to 4 C atoms wherein one or more H atoms are optionally replaced by F.

Very preferred are substituents of formula R1 , R2, R3 and R4 wherein a is 3 or more. Further preferred are substituents of formula R1 , R2, R3 and R4 wherein b is 5 or more.

Very preferred are substituents of formula R5 and R6 wherein d is 3 or more. Further preferred are substituents of formula R5 and R6 wherein e is 5 or more.

Very preferred are substituents of formula R10 and R11 wherein g is 3 or more.

In the compounds of formula F and its subformulae, Ar is preferably selected from formula C1 and C2, which are optionally substituted by or more groups L as defined above.

Very preferably Ar denotes benzene that is optionally substituted by one or more groups L as defined above.

In addition to the adduct -C(Ar)(R¹)- in formula F, the fullerene C_n may have any number (m) of second adducts Ad different from -C(Ar)(R¹)-. The second adduct Ad may be any possible adduct or combination of adducts with any connectivity to the fullerene.

The adduct Ad is preferably appended to the fullerene Cn by the [6,6]-bond and/or [5,6]-bond, preferably on at least one [6,6]-bond.

In the compounds of formula F and its subformulae, the number m of second adducts Ad appended to the fullerene C_n is 0, an integer > 1 , or a non-integer > 0 like 0.5 or 1.5, and is preferably 0, 1 or 2.

In a preferred embodiment the number m of the second adducts Ad appended to the fullerene Cn is 0.

In another preferred embodiment the number m of the second adducts Ad appended to the fullerene C_n is >0, preferably 1 or 2.

The second adduct Ad in formula I and its subformulae is preferably selected from the following formulae

S-14 wherein

R^S1, R^S2, R^S3, R^S4 and R^S5 independently of each other denote H, halogen or CN, or have one of the meanings of R¹ or L as given above and below, and Ar³¹ and Ar^S2 independently of each other denote an aromatic or heteroaromatic group with 4 to 30 ring C atoms that is mono- or polycyclic, optionally contains fused rings, and is optionally substituted with one or more groups L as defined above and below. Preferably Ar⁵¹ and Ar⁵² are selected form the following formulae

(A10) which are optionally substituted by one or more groups R¹¹ or L as defined above and below.

In the compounds of formula F and its subformulae, all adducts -C(Ar)(R¹)- and Ad may be connected to one another in any combination in the finished product or during synthesis, to facilitate preferred properties in the finished product. Further preferred compounds of formula F and its subformulae are selected from the following preferred embodiments, including any combination thereof:

- m is 0,

- o is 1 or 2,

- m is 0 and o is 1 or 2,

- n is 60 or 70,

- n is 60,

- Ar denotes benzene or thiophene, very preferably benzene, which is optionally substituted by one or more groups L.

- R¹ is selected from formulae R1 to R11 , very preferably from formula R1 or R10.

Examples of preferred compounds of formula F are listed below

(PCBC6-C60)

(PCBC8-C60)

(PCBEH-C60)

wherein the fullerene is C60. Further preferred compounds are those of formula F1 to F6 shown above, wherein the fullerene is C70 instead of C60.

The compounds of formula F are easy to synthesize, especially by methods suitable for mass production, and exhibit advantageous properties, for example good structural organization and film-forming properties, good electronic properties, especially high charge carrier mobility, good processability, especially high solubility in organic solvents, and high light and thermal stability.

The compounds of formula F can be synthesized according to or in analogy to methods that are known to the skilled person and are described in the literature. For example, synthesis paths towards various fullerenes of formula I have been previously outlined in literature: J. Mater. Chem., 1997, 7(7), 1097-1109; Chem. Soc. Rev., 1999, 28, 263-277; Chem. Rev. 2013, 113, 5262-5321; J. Am. Chem. Soc. 2011 , 133, 2402-2405; and Chem. Rev., 2006, 106(12), 5049-5135.

The conjugated polymer as used in a mixture of the present invention (hereinafter also shortly referred to as "polymer") comprises one or more units of formula 1 and one or more units of formula 2

wherein the individual radicals are as defined above. Preferably the polymer comprises, in addition to the units of formula 1 and 2, one or more spacer units Sp selected from the group consisting of the following formulae

wherein R¹¹ and R ² are as defined in formula 1. Preferred spacer units are selected from formula Sp1, Sp4 and Sp6, wherein preferably one of R¹¹ and R¹² is H or both R¹¹ and R¹² are H.

Preferred polymers comprise, very preferably consist of, one or more units of the formula 1a and one or more units of the formula 2a

-(D-Sp)- 1a

-(A-Sp)- 2a wherein D denotes a unit of formula 1 , A denotes a unit of formula 2 and Sp denotes a unit selected from formulae Sp1 to Sp16, very preferably from formulae Sp1 and Sp6. Preferred polymers consist of one or more units of formula 1 , one or more units of formula 2 and optionally one or more spacer units selected from formulae Sp1 to Sp16.

Very preferred are polymers of formula P

-[(D-Sp)x-(A-S_P)y]n- P wherein A, D and Sp are as defined in formula 1a and 2a, x denotes the molar fraction of the units (D-Sp), y denotes the molar fraction of the units (A- Sp), x and y are each, independently of one another > 0 and <1 , with x+y=1 , and n is an integer >1.

Preferred polymers of formula P are selected from the following subformulae

wherein R^11"16, x, y and n are as defined in formula 1 , 2 and P.

Preferably R¹¹ and R¹² in formulae Sp1 to Sp16, P1 and P2 are H. Preferably R¹³ and R ⁴ in formula 1 , P1 and P2 are different from H.

Preferably R¹⁵ and R¹⁶ in formula 1 , P1 and P2 are H.

Preferably R¹⁷ and R¹⁸ in formula 2, P1 and P2 are different from H.

Preferably R¹ , R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷ and R¹⁸ in formulae 1 , 2, Sp1- Sp16, P1 and P2, when being different from H, are selected from the following groups:

- the group consisting of straight-chain or branched alkyl with 1 to 30, preferably 1 to 20, C atoms that is optionally fluorinated,

- the group consisting of straight-chain or branched alkyl, alkoxy or

sulfanylalkyl with 1 to 30, preferably 1 to 20, C atoms, and straight- chain or branched alkylcarbonyl, alkylcarbonyloxy or alkyloxycarbonyl with 2 to 30, preferably 2 to 20, C atoms, each of the aforementioned groups being unsubstituted or substituted by one or more F atoms.

Very preferably R¹³ and R¹⁴ in formula 1 , P1 and P2 denote -CO-0-R^x, with R^x being straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated.

Very preferably R¹⁷ and R¹⁸ in formula 2, P1 and P2 denote R^x or -OR^x, with R^x being straight-chain or branched alkyl with 1 to 20 C atoms that is optionally fluorinated.

In the polymers of formulae P, P1 and P2, x and y are preferably from 0.1 to 0.9, very preferably from 0.3 to 0.7, most preferably from 0.4 to 0.6.

In the polymers according to the present invention, the total number of repeating units n is preferably from 2 to 10,000. The total number of repeating units n is preferably > 5, very preferably > 10, most preferably > 50, and preferably < 500, very preferably < 1 ,000, most preferably < 2,000, including any combination of the aforementioned lower and upper limits of n. The polymers of the present invention are preferably statistical or random copolymers.

Further preferred is conjugated polymer according to the present invention selected of formula PT

R³¹-chain-R³² PT wherein "chain" denotes a polymer chain selected of formula P, P1 or P2, and R³¹ and R³² have independently of each other one of the meanings of R ¹ as defined above, or denote, independently of each other, H, F, Br, CI, I, -CH2CI, -CHO, -CR^CR^, -SiR^,R"R^,,, _I -SiRXX", -SiR'R'X, -SnR'R"R^m, - BR'R", -B(OR')(OR"), -B(OH)₂, -0-SO₂-R', -C≡CH, -C≡C-SiR'3, -ZnX' or an endcap group, X' and X" denote halogen, R', R" and R'" have

independently of each other one of the meanings of R° given in formula 1 , and preferably denote alkyl with 1 to 12 C atoms, and two of R', R" and R"' may also form a cyclosilyl, cyclostannyl, cycloborane or cycloboronate group with 2 to 20 C atoms together with the respective hetero atom to which they are attached.

Preferred endcap groups R³¹ and R³² are H, Ci-2o alkyl, or optionally substituted C6-12 aryl or C2-10 heteroaryl, very preferably H or phenyl.

The conjugated polymer can be prepared for example by copolymerising one or more monomers selected from the following formulae in an aryl-aryl coupling reaction

R³³-D-R³⁴ Ml R^-A-R³⁴ MM

R³³-Sp-R³⁴ Mill wherein at least one monomer is selected of formula Ml and at least one monomer is selected of formula Mil, D denotes a unit of formula 1 ,

A denotes a unit of formula 2, Sp denotes a spacer unit selected from formulae Sp1 to Sp16,

R³³ and R³⁴ are, independently of each other, selected from the group consisting of H which is preferably an activated C-H bond, CI, Br, I, O- tosylate, O-triflate, O-mesylate, O-nonaflate, -SiMe2F, -SiMeF₂, -O-SO2Z¹, - B(OZ²)2 , -CZ³=C(Z³)₂, -C≡CH, - C≡CSi(Z¹)₃, -ZnX⁰⁰ and -Sn(Z⁴)₃, wherein X⁰⁰ is halogen, preferably CI, Br or I, Z^1"4 are selected from the group consisting of alkyl, preferably Ci-ioalkyl and aryl, preferably C6-i2 aryl, each being optionally substituted, and two groups Z² may also form a

cycloboronate group having 2 to 20 C atoms with the B- and O-atoms.

The monomers of formula MI-MIII can be co-polymerised with each other and/or with other suitable co-monomers.

The polymer according to the present invention can be synthesized according to or in analogy to methods that are known to the skilled person and are described in the literature. Other methods of preparation can be taken from the examples.

For example, the polymers can be suitably prepared by aryl-aryl coupling reactions, such as Yamamoto coupling, C-H activation coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling or Buchwald coupling. Suzuki coupling, Stille coupling and Yamamoto coupling are especially preferred. The monomers which are polymerised to form the repeat units of the polymers can be prepared according to methods which are known to the person skilled in the art.

Preferably the polymer is prepared from monomers selected from formulae MI-MVI as described above. Another aspect of the invention is a process for preparing a polymer by coupling one or more identical or different monomers selected from formula MI-MIII with each other and/or with one or more co-monomers in a polymerisation reaction, preferably in an aryl-aryl coupling reaction.

Preferred aryl-aryl coupling and polymerisation methods used in the processes described above and below are Yamamoto coupling, Kumada coupling, Negishi coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling, C-H activation coupling, Ullmann coupling or Buchwald coupling. Especially preferred are Suzuki coupling, Negishi coupling, Stille coupling and Yamamoto coupling. Suzuki coupling is described for example in WO 00/53656 A1. Negishi coupling is described for example in J. Chem. Soc, Chem. Commun., 1977, 683-684.

Yamamoto coupling is described in for example in T. Yamamoto ef a/., Prog. Polym. Sci., 1993, 17, 1153-1205, or WO 2004/022626 A1. Stille coupling is described for example in Z. Bao et al., J. Am. Chem. Soc, 1995, 117, 12426-12435. C-H activation is described for example for example in M. Leclerc et al, Angew. Chem. Int. Ed. 2012, 51, 2068 - 2071. For example, when using Yamamoto coupling, monomers having two reactive halide groups are preferably used. When using Suzuki coupling, monomers having two reactive boronic acid or boronic acid ester groups or two reactive halide groups are preferably used. When using Stille coupling, monomers having two reactive stannane groups or two reactive halide groups are preferably used. When using Negishi coupling, monomers having two reactive organozinc groups or two reactive halide groups are preferably used. When synthesizing a linear polymer by C-H activation polymerisation, preferably a monomer as described above is used wherein at least one reactive group is an activated hydrogen bond.

Preferred catalysts, especially for Suzuki, Negishi or Stille coupling, are selected from Pd(0) complexes or Pd(ll) salts. Preferred Pd(0) complexes are those bearing at least one phosphine ligand such as Pd(Ph3P)4. Another preferred phosphine ligand is tris(orf/70-tolyl)phosphine, i.e. Pd(o-To P)4. Preferred Pd(ll) salts include palladium acetate, i.e. Pd(OAc)2 or trans-di(p- acetato)-bis[o-(di-o-tolylphosphino)benzyl]dipalladium(ll). Alternatively the Pd(0) complex can be prepared by mixing a Pd(0) dibenzylideneacetone complex, for example tris(dibenzyl-ideneacetone)dipalladium(0),

bis(dibenzylideneacetone)palladium(0), or Pd(ll) salts e.g. palladium acetate, with a phosphine ligand, for example triphenylphosphine, iris(ortho- tolyl)phosphine, tris(o-methoxyphenyl)phosphine or tri(tert-butyl)phosphine. Suzuki polymerisation is performed in the presence of a base, for example sodium carbonate, potassium carbonate, cesium carbonated, lithium hydroxide, potassium phosphate or an organic base such as

tetraethylammonium carbonate or tetraethylammonium hydroxide.

Yamamoto polymerisation employs a Ni(0) complex, for example bis(1 ,5- cyclooctadienyl) nickel(O). Suzuki, Stille or C-H activation coupling polymerisation may be used to prepare homopolymers as well as statistical, alternating and block random copolymers. Statistical, random block copolymers or block copolymers can be prepared for example from the above monomers, wherein one of the reactive groups is halogen and the other reactive group is a C-H activated bond, boronic acid, boronic acid derivative group or and alkylstannane.

The synthesis of statistical, alternating and block copolymers is described in detail for example in WO2003/048225 A2 or WO 2005/014688 A2.

As alternatives to halogen as described above, leaving groups of formula - O-SO2Z¹ can be used wherein Z¹ is as defined above. Particular examples of such leaving groups are tosylate, mesylate and triflate.

The generic preparation of the BTZ-F2 monomers of formula A has been described for example in WO 2011/060526 A1.

The synthesis of the bithiophene monomers of formula D has been described for example in Macromolecules, 2007, 40(26), Organometallics 2011 , 30, 3233-3236, Macromolecules, 2007, 40(6) and J. Am. Chem. Soc. 2008, 130, 13167-13176.

In a mixture according to the present invention (i.e. excluding solvents), the concentration of the compounds of formula F is preferably from 40 to 90% by weight, very preferably from 50 to 70% by weight. In a mixture according to the present invention (i.e. excluding solvents), the concentration of the conjugated polymer is preferably from 10 to 60% by weight, very preferably from 30 to 50% by weight.

In a mixture according to the present invention, the ratio polymenfullerene is preferably from 5:1 to 1 :5 by weight, more preferably from 1 :0.5 to 1 :3 by weight, most preferably 1 :1 to 1 :2 by weight.

In another preferred embodiment of the present invention, the mixture further comprises one or more binders to adjust the rheological properties as described for example in WO 2005/055248A1. Suitable and preferred binders are polymeric binders, like for example polystyrene (PS), polypropylene (PP) and polymethylmethacrylate (PMMA). The binder may be added to the mixture in a concentration from 5 to 95% by weight of total solids (i.e. without solvents). The mixture according to the present invention can be used together with other monomeric compounds, or polymers, having one or more of a semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting and light emitting property

Thus, another aspect of the invention relates to a mixture comprising a conjugated polymer and a fullerene as defined above, and further comprising one or more additional compounds, preferably having one or more of a semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting and light emitting property.

Another aspect of the present invention relates to a formulation comprising a mixture of a conjugated polymer and a fullerene compound of formula F as described above, and further comprising one or more solvents, preferably selected from organic solvents.

Such a formulation is preferably used as a carrier for the preparation of a semiconducting layer of an OE device, like an OPV or OPD device, wherein the fullerene derivative or fullerene composition is for example used in the photoactive layer. in a formulation according to the present invention (i.e. including solvents), the concentration of the mixture of this invention is preferably from 0.1 to 10% by weight, more preferably 0.5 to 5% by weight.

The formulation according to the present invention preferably forms a solution.

The invention additionally provides an OE device comprising a mixture according to the present invention, and an OE device comprising a semiconducting or photoactive layer (hereinafter also referred to as "active layer"), comprising a mixture according to the present invention as described above and below. Preferred OE devices are OFETs, TFTs, ICs, logic circuits, capacitors, RFID tags, OLEDs, OLETs, OPEDs, OPVs, OPDs, organic solar cells, DSSCs, perovskite based solar cells, laser diodes, photoconductors, photodetectors, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates and conducting patterns.

Especially preferred electronic device are OFETs, OLEDs, OPV and OPD devices, in particular bulk heterojunction (BHJ) OPV devices and OPD devices. In an OPV or OPD device, for example, the photoactive layer may comprise a mixture according to the present invention. In an OFET, for example, the active semiconductor channel between the drain and source may comprise a semiconducting layer comprising a mixture according to the present invention. As another example, in an OLED device, the charge (hole or electron) injection or transport layer may comprise may comprise a mixture according to the present invention.

The mixture according to the present invention is especially suitable as photoactive material for use in the photoactive layer of an OPV, BHJ OPV or OPD device. Therein the conjugated polymer(s) comprising units of formula 1 and 2 act as electron donor or p-type semiconductor component, and the fullerene(s) of formula F act as electron acceptor or n- type semiconductor component. The fullerene(s) and conjugated polymer(s) are preferably selected such that the mixture forms a bulk heterojunction.

The OPV or OPD device preferably further comprises a first transparent or semi-transparent electrode on a transparent or semi-transparent substrate on one side of the active layer, and a second metallic or semi-transparent electrode on the other side of the active layer.

In another prefered embodiment, the photoactive layer comprises a mixture according to the present invention that further comprises one or more organic or inorganic compounds or materials to enhance the device properties. Suitable and preferred example of such additional compounds or materials are selected from metal particles, such as Au or Ag

nanoparticules or Au or Ag nanoprism for enhancements in light harvesting due to near-field effects (i.e. plasmonic effect) as described, for example in Adv. Mater. 2013, 25 (17), 2385-2396 and Adv. Ener. Mater. 10.1002/aenm.201400206, a molecular dopant such as 2,3,5,6-tetrafluoro- 7,7,8,8-tetracyanoquinodimethane for enhancement in photoconductivity as described, for example in Adv. Mater. 2013, 25(48), 7038-7044, or a stabilising agent consisting of a UV absorption agent and/or anti-radical agent and/or antioxidant agent such as 2-hydroxybenzophenone, 2- hydroxyphenylbenzotriazole, oxalic acid anilides, hydroxyphenyl triazines, merocyanines, hindered phenol, N-aryl-thiomorpholine, N-aryl- thiomorpholine-1 -oxide, N-aryl-thiomorpholine-1 ,1 -dioxide, N-aryl- thiazolidine, N-aryl-thiazolidine-1 -oxide, N-aryl-thiazolidine-1 ,1 -dioxide and 1 ,4-diazabicyclo[2.2.2]octane as described, for example, in

WO20 2095796 A1 and in WO2013021971 A1.

The OPV or OPD device preferably further comprises a UV to visible photo-conversion layer such as described, for example, in J. Mater. Chem. 2011 , 21, 12331 or a NIR to visible or IR to NIR photo-conversion layer such as described, for example, in J. Appl. Phys. 2013, 113, 124509.

The OPV or OPD device may further comprise, between the active layer and an electrode, additional interfacial layer(s) acting as hole blocking layer, hole transporting layer, electron blocking layer and/or electron transporting layer, typically comprising a metal oxide (for example, ZnOx, TiOx, ZTO, MoOx, NiOx), a salt (example: LiF, NaF), a conjugated polymer electrolyte (for example: PEDOTPSS or PFN), a conjugated polymer (for example: PTAA) or an organic compound (for example: NPB, Alq3, TPD), can be inserted.

Preferably the OPV or OPD device comprises, between the active layer and the first or second electrode, one or more additional buffer layers acting as hole transporting layer and/or electron blocking layer, which comprise a material such as metal oxides, like for example, ZTO, MoOx, NiOx, a doped conjugated polymer, like for example PEDOT:PSS and polypyrrole-polystyrene sulfonate (PPy:PSS), a conjugated polymer, like for example polytriarylamine (PTAA), an organic compound, like for example substituted triaryl amine derivatives such as N,N'-diphenyl-N,N'- bis(1-naphthyl)(1 ,1'-biphenyl)-4,4'diamine (NPB), N.N'-diphenyl-N.N'-iS- methylphenyl)-1 ,1'-biphenyl-4,4'-diamine (TPD), graphene based materials, like for example, graphene oxide, reduced graphene oxide, graphene, graphene nanoribbons and graphene quantum dots or alternatively as hole blocking layer and/or electron transporting layer, which comprise a material such as metal oxide, like for example, ZnOx, TiOx, AZO (aluminium doped zinc oxide), a salt, like for example LiF, NaF, CsF, a conjugated polymer electrolyte, like for example poly[3-(6- trimethylammoniumhexyl)thiophene], poly(9,9-bis(2-ethylhexyl)- fluorene]-i)-poly[3-(6-trimethylammoniumhexyl)thiophene], or poly[(9,9- bis(3^'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9- dioctylfluorene)], a polymer, like for example poly(ethyleneimine) or crosslinked N-containing compound derivatives or an organic compound, like for example tris(8-quinolinolato)-aluminium(lll) (Alq3), phenanthroline derivative or C60 or C70 based fullerenes, like for example, as described in Adv. Energy Mater. 2012, 2, 82-86.

To produce thin layers in OE devices, like BHJ OPV devices, a mixture or formulation according to the present invention may be deposited by any suitable method. Liquid coating of devices is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. The formulations of the present invention enable the use of a number of liquid coating techniques. Preferred deposition techniques include, without limitation, dip coating, spin coating, ink jet printing, nozzle printing, letter-press printing, screen printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, dry offset lithography printing, flexographic printing, web printing, spray coating, curtain coating, brush coating, slot dye coating or pad printing. For the fabrication of OPV devices and modules area printing method compatible with flexible substrates are preferred, for example slot dye coating, spray coating and the like.

When preparing a suitable solution or formulation containing a mixture with a fullerene (as n-type component) and a polymer (as p-type

component) according to the present invention, a suitable solvent should be selected so as to ensure full dissolution of both the p-type and the n- type component, and to take into account the boundary conditions (for example rheological properties) introduced by the chosen printing method. Organic solvents are generally used for this purpose. Typical solvents can be aromatic solvents, halogenated solvents or chlorinated solvents, including chlorinated aromatic solvents. Preferred solvents are aliphatic hydrocarbons, chlorinated hydrocarbons, aromatic hydrocarbons, ketones, ethers and mixtures thereof. Examples include, but are not limited to dichloromethane, trichloromethane, tetrachloromethane, chlorobenzene, o-dichlorobenzene, 1 ,2,4-trichlorobenzene, 1 ,2-dichloroethane, 1 ,1,1- trichloroethane, 1 ,1 ,2,2-tetrachloroethane, 1 ,8-diiodooctane, 1- chloronaphthalene, 1 ,8-octane-dithiol, anisole, 2-methylanisole, phenetol, 4-methyl-anisole, 3-methylanisole, 2,6-dimethylanisole, 2,5-di- methylanisole, 2,4-dimethylanisole, 3,5-dimethyl-anisole, 4-fluoroanisole, 3-fluoro-anisole, 3-trifluoro-methylanisole, 4-fluoro-3-methylanisole, 2- fluoroanisole, toluene, o-xylene, m-xylene, p-xylene, mixture of xylene o-, m-, and p-isomers, 1 ,2,4-trimethylbenzene, 1 ,2,3,4-tetra-methyl benzene, pentylbenzene, mesitylene, cumene, cymene, cyclohexylbenzene, diethylbenzene, cyclohexane, 1-methylnaphthalene, 2-methylnaphthalene, 1 ,2-dimethylnaphthalene, tetraline, decaline, indane, 1-methyl-4-(1- methylethenyl)-cyclohexene (d-Limonene), 6,6-dimethyl-2- methylenebicyclo[3.1.1]heptanes (β -pinene), 2,6-lutidine, 2-fluoro-m- xylene, 3-fluoro-o-xylene, 2-chloro-benzotrifluoride, 2-chloro-6- fluorotoluene, 2,3-dimethylpyrazine, 2-fluorobenzonitrile, 4-fluoroveratrol, 3-fluorobenzo-nitrile, 1-fluoro-3,5-dimethoxy-benzene, 3-fluorobenzo- trifluoride, benzotrifluoride, trifluoromethoxy-benzene, 4- fluorobenzotrifluoride, 3-fluoropyridine, toluene, 2-fluoro-toluene, 2- fluorobenzotrifluoride, 3-fluorotoluene, 4-isopropylbiphenyl, phenyl ether, pyridine, 4-fluorotoluene, 2,5-difluorotoluene, 1-chloro-2,4- difluorobenzene, 2-fluoropyridine, 3-chlorofluoro-benzene, 1-chloro-2,5- difluorobenzene, 4-chlorofluorobenzene, 2-chlorofluorobenzene, methyl benzoate, ethyl benzoate, nitrobenzene, benzaldehyde, benzonitrile, tetrahydrofuran, 1 ,4-dioxane, 1,3-dioxane, morpholine, acetone, methylethylketone, ethyl acetate, n-butyl acetate, N,N-dimethylaniline, Ν,Ν-dimethylformamide, N-methylpyrrolidinone, dimethylacetamide, dimethylsulfoxide and/or mixtures thereof.

Especially preferred are solvents selected from aliphatic or aromatic hydrocarbons, or mixtures thereof, which are non-chlorinated.

Further preferred are solvents selected from non-chlorinated aliphatic or aromatic hydrocarbons, or mixtures thereof, which contain less than 5% of halogenated but non-chlorinated (e.g. fluorinated, brominated or iodinated) aliphatic or aromatic hydrocarbons, like e.g. 1 ,8-diiodooctane.

Preferred solvents of this type are selected from 1 ,2,4-trimethylbenzene, 1 ,2,3,4-tetra-methyl benzene, pentylbenzene, mesitylene, cumene, cymene, cyclohexylbenzene, diethylbenzene, tetralin, decalin, 2,6-lutidine, Ν,Ν-dimethylformamide, 2,3-dimethylpyrazine, 2-methylanisole, phenetol, 4-methyl-anisole, 3-methylanisole, 2,5-dimethyl-anisole, 2,4- dimethylanisole, 3,5-dimethyl-anisole, Ν,Ν-dimethylaniline, ethyl benzoate, 1 -methylnaphthalene, 2-methylnaphthalene, N-methylpyrrolidinone, dioxane, 4-isopropylbiphenyl, phenyl ether, 2-methylthiophene, pyridine, 1,8-octanedithiol, nitrobenzene, 1-chloronaphthalene, p-xylene, m-xylene, o-xylene or mixture of o-, m-, and p-isomers. The OPV device can be of any OPV device type known from the literature (see e.g. Waldauf er a/., Appl. Phys. Lett, 2006, 89, 233517).

A first preferred OPV device according to the invention comprises the following layers (in the sequence from bottom to top):

- optionally a substrate,

- a high work function electrode, preferably comprising a metal oxide, like for example ITO, serving as anode or a conducting grid

- an optional conducting polymer layer or hole transport layer, preferably comprising an organic polymer or polymer blend, for example

PEDOT.PSS (poly(3,4-ethylenedioxythiophene): poly(styrene- sulfonate), substituted triaryl amine derivatives, for example.TBD (Ν,Ν'- dyphenyl-N-N'-bis(3-methylphenyl)-1 ,1'biphenyl-4,4'-diamine) or NBD (N,N'-dyphenyl-N-N'-bis(1-napthylphenyl)-1 ,1'biphenyl-4,4'-diamine), - a layer, also referred to as "photoactive layer", comprising a p-type and an n-type organic semiconductor, which can exist for example as a p- type/n-type bilayer or as distinct p-type and n-type layers, or as blend or p-type and n-type semiconductor, forming a BHJ,

- optionally a layer having electron transport properties, for example comprising LiF, TiOx, ZnOx, PFN, a poly(ethyleneimine) or crosslinked nitrogen containing compound derivatives or a phenanthroline derivatives

- a low work function electrode, preferably comprising a metal like for example aluminum, serving as cathode,

wherein at least one of the electrodes, preferably the anode, is at least partially transparent to visible light, and

wherein the photoactive layer contains a mixture according to the present invention.

A second preferred OPV device according to the invention is an inverted OPV device and comprises the following layers (in the sequence from bottom to top):

- optionally a substrate,

- a high work function metal or metal oxide electrode, comprising for example ITO, serving as cathode, or a conducting grid - a layer having hole blocking properties, preferably comprising a metal oxide like TiOx or ZnOx, or comprising an organic compound such as polymer like poly(ethyleneimine) or crosslinked nitrogen containing compound derivatives or phenanthroline derivatives,

- a photoactive layer comprising a p-type and an n-type organic

semiconductor, situated between the electrodes, which can exist for example as a p-type/n-type bilayer or as distinct p-type and n-type layers, or as blend or p-type and n-type semiconductor, forming a BHJ,

- an optional conducting polymer layer or hole transport layer, preferably comprising an organic polymer or polymer blend, for example of PEDOT:PSS or substituted triaryl amine derivatives, for example, TBD or NBD,

- an electrode comprising a high work function metal like for example silver, serving as anode,

wherein at least one of the electrodes, preferably the cathode, is at least partially transparent to visible light, and

wherein the photoactive layer contains a mixture according to the present invention.

In the OPV devices of the present invention the p-type and n-type semiconductor materials are preferably selected from the materials, like the polymer/fullerene systems, as described above

When the photoactive layer is deposited on the substrate, it forms a BHJ that phase separates at nanoscale level. For discussion on nanoscale phase separation see Dennler et al, Proceedings of the IEEE, 2005, 93 (8), 1429 or Hoppe et al, Adv. Func. Mater, 2004, 14(10), 1005. An optional annealing step may be then necessary to optimize blend morpohology and consequently OPV device performance.

Another method to optimize device performance is to prepare formulations for the fabrication of OPV(BHJ) devices that may include additives with variable boiling points to promote phase separation in the right way. 1 ,8- Octanedithiol, 1 ,8-diiodooctane, nitrobenzene, 1-chloronaphthalene, N,N- dimethylformamide, dimethylacetamide, dimethylsulfoxide and other additives have been used to obtain high-efficiency solar cells. Examples are disclosed in J. Peet, ef al, Nat. Mater., 2007, 6, 497 or Frechet et al. J. Am. Chem. Soc, 2010, 132, 7595-7597. As further illustrated in the non-limiting working examples, photovoltaic devices can be prepared which have a power conversion efficiency (PCE) of, for example, at least 2.5%, or at least 3.0%, or at least 4.0%, or at least 5.0%. While there is no particular upper limit on the PCE, the PCE can be, for example, less than 20%, or less than 15%, or less than 10%.

Another preferred embodiment of the present invention relates to the use of a mixture according to the present invention as dye, hole transport layer, hole blocking layer, electron transport layer and/or electron blocking layer in a DSSC or a perovskite-based solar cells, and to a DSSC or perovskite-based solar cells comprising a mixture according to the present invention.

DSSCs and perovskite-based solar cells can be manufactured as described in the literature, for example in Chem. Rev. 2010, 110, 6595- 6663, Angew. Chem. Int. Ed. 2014, 53, 2-15 or in WO2013171520A1.

The mixtures of the present invention can also be used as dye or pigment in other applications, for example as an ink dye, laser dye, fluorescent marker, solvent dye, food dye, contrast dye or pigment in coloring paints, inks, plastics, fabrics, cosmetics, food and other materials.

The mixtures and semiconducting layers of the present invention are also suitable for use as n-type semiconductor in other OE devices or device components, for example in the semiconducting channel of an OFET device, or in the buffer layer, electron transport layer (ETL) or hole blocking layer (HBL) of an OLED or OPV device.

Accordingly, the invention also provides an OFET comprising a gate electrode, an insulating (or gate insulator) layer, a source electrode, a drain electrode and an organic semiconducting channel connecting the source and drain electrodes, wherein the organic semiconducting channel comprises a mixture according to the present invention as semiconductor. Other features of the OFET are well known to those skilled in the art.

OFETs where an OSC material is arranged as a thin film between a gate dielectric and a drain and a source electrode, are generally known, and are described for example in US 5,892,244, US 5,998,804, US 6,723,394 and in the references cited in the background section. Due to the advantages, like low cost production using the solubility properties of the compounds according to the invention and thus the processibility of large surfaces, preferred applications of these FETs are such as integrated circuitry, TFT displays and security applications.

The gate, source and drain electrodes and the insulating and

semiconducting layer in the OFET device may be arranged in any sequence, provided that the source and drain electrode are separated from the gate electrode by the insulating layer, the gate electrode and the semiconductor layer both contact the insulating layer, and the source electrode and the drain electrode both contact the semiconducting layer. An OFET device according to the present invention preferably comprises:

- a source electrode,

- a drain electrode,

- a gate electrode,

- a semiconducting layer,

- one or more gate insulator layers,

- optionally a substrate. wherein the semiconductor layer comprises a mixture according to the present invention.

The OFET device can be a top gate device or a bottom gate device.

Suitable structures and manufacturing methods of an OFET device are known to the skilled in the art and are described in the literature, for example in US 2007/0102696 A1.

The gate insulator layer preferably comprises a fluoropolymer, like e.g. the commercially available Cytop 809M® or Cytop 107M® (from Asahi Glass). Preferably the gate insulator layer is deposited, e.g. by spin-coating, doctor blading, wire bar coating, spray or dip coating or other known methods, from a formulation comprising an insulator material and one or more solvents with one or more fluoro atoms (fluorosolvents), preferably a perfluorosolvent. A suitable perfluorosolvent is e.g. FC75® (available from Acros, catalogue number 12380). Other suitable fluoropolymers and fluorosolvents are known in prior art, like for example the

perfluoropolymers Teflon AF® 1600 or 2400 (from DuPont) or Fluoropel® (from Cytonix) or the perfluorosolvent FC 43® (Acros, No. 12377).

Especially preferred are organic dielectric materials having a low

permittivity (or dielectric contant) from 1.0 to 5.0, very preferably from 1.8 to 4.0 ("low k materials"), as disclosed for example in US 2007/0102696 A1 or US 7,095,044.

In security applications, OFETs and other devices with semiconducting materials according to the present invention, like transistors or diodes, can be used for RFID tags or security markings to authenticate and prevent counterfeiting of documents of value like banknotes, credit cards or ID cards, national ID documents, licenses or any product with monetry value, like stamps, tickets, shares, cheques etc.

Alternatively, the mixtures and semiconducting layers according to the invention can be used in OLEDs, for example in the buffer layer, ETL or HBL of an OLED. The OLED device can be used for example as the active display layer in a flat panel display device, or as the backlight of a flat panel display like for example a liquid crystal display. Common OLEDs are realized using multilayer structures. An emission layer is generally sandwiched between one or more electron-transport and/or hole-transport layers. By applying an electric voltage electrons and holes as charge carriers move towards the emission layer where their recombination leads to the excitation and hence luminescence of the lumophor units contained in the emission layer. The mixture or semiconducting layer according to the present invention may be employed in one or more of the ETL, HBL or buffer layer, especially their water-soluble derivatives (for example with polar or ionic side groups) or ionically doped forms. The processing of such layers, comprising a semiconductor material of the present invention, for the use in OLEDs is generally known by a person skilled in the art, see, e.g., Muller ef al, Synth. Metals, 2000, 111-112, 31-34, Alcala, J. Appl. Phys., 2000, 88, 7124-7128, O'Malley ef al, Adv. Energy Mater. 2012, 2, 82-86 and the literature cited therein.

According to another use, the mixtures according to this invention, especially those showing photoluminescent properties, may be employed as materials of light sources, e.g. in display devices, as described in EP 0 889 350 A1 or by C. Weder et al., Science, 1998, 279, 835-837.

A further aspect of the invention relates to both the oxidised and reduced form of a mixture according to this invention. Either loss or gain of electrons results in formation of a highly delocalised ionic form, which is of high conductivity. This can occur on exposure to common dopants.

Suitable dopants and methods of doping are known to those skilled in the art, e.g. from EP 0 528 662, US 5,198,153 or WO 96/21659.

The doping process typically implies treatment of the semiconductor material with an oxidating or reducing agent in a redox reaction to form delocalised ionic centres in the material, with the corresponding

counterions derived from the applied dopants. Suitable doping methods comprise for example exposure to a doping vapor in the atmospheric pressure or at a reduced pressure, electrochemical doping in a solution containing a dopant, bringing a dopant into contact with the semiconductor material to be thermally diffused, and ion-implantantion of the dopant into the semiconductor material.

When electrons are used as carriers, suitable dopants are for example halogens (e.g., h, CI2, Βτ2, ICI, ICb, IBr and IF), Lewis acids (e.g., PF5, AsF5, SbFs, BF3, BCb, SbC , BBr3 and SO3), protonic acids, organic acids, or amino acids (e.g., HF, HCI, HNO3, H2SO4, HCIO₄, FSO3H and CISO3H), transition metal compounds (e.g., FeC , FeOCI, Fe(CIO4)3,

Fe(4-CH3C₆H4SO3)3, TiCU, ZrCU, HfCU, NbF₅, NbCIs, TaCIs, M0F5, M0CI5, WF5, WC , UF6 and LnC (wherein Ln is a lanthanoid), anions (e.g., CI^", Br, I^", Is^", HSO4-, SO4²-, NO3-, CI04-, BF4-, PFe-, AsFe^", SbFe^", FeC ^",

Fe(CN)6^3", and anions of various sulfonic acids, such as aryl-SO₃ ). When holes are used as carriers, examples of dopants are cations (e.g., FT, Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺), alkali metals (e.g., Li, Na, K, Rb, and Cs), alkaline- earth metals (e.g., Ca, Sr, and Ba), O2, XeOF₄, (N0₂ ⁺) (SbFe ), (N0₂ ⁺) (SbCle^"), (N0₂ ⁺) (BF4-), AgCIO₄, H₂lrCI₆, La(NO₃)₃ 6H2O, FSO2OOSO2F, Eu, acetylcholine, R4N⁺, (R is an alkyl group), R P⁺ (R is an alkyl group), R6As⁺ (R is an alkyl group), and R₃S⁺ (R is an alkyl group).

The conducting form of a mixture of the present invention can be used as an organic "metal" in applications including, but not limited to, charge injection layers and ITO planarising layers in OLED applications, films for flat panel displays and touch screens, antistatic films, printed conductive substrates, patterns or tracts in electronic applications such as printed circuit boards and condensers.

According to another use, the mixtures according to the present invention can be used alone or together with other materials in or as alignment layers in LCD or OLED devices, as described for example in US

2003/0021913. The use of charge transport compounds according to the present invention can increase the electrical conductivity of the alignment layer. When used in an LCD, this increased electrical conductivity can reduce adverse residual dc effects in the switchable LCD cell and suppress image sticking or, for example in ferroelectric LCDs, reduce the residual charge produced by the switching of the spontaneous polarisation charge of the ferroelectric LCs. When used in an OLED device comprising a light emitting material provided onto the alignment layer, this increased electrical conductivity can enhance the electroluminescence of the light emitting material. The mixtures according to the present invention may also be combined with photoisomerisable compounds and/or

chromophores for use in or as photoalignment layers, as described in US 2003/0021913 A1.

According to another use the mixtures according to the present invention, especially their water-soluble derivatives (for example with polar or ionic side groups) or ionically doped forms, can be employed as chemical sensors or materials for detecting and discriminating DNA sequences. Such uses are described for example in L. Chen, D. W. McBranch, H. Wang, R. Helgeson, F. Wudl and D. G. Whitten, Proc. Natl. Acad. Sci. U.S.A., 1999, 96, 12287; D. Wang, X. Gong, P. S. Heeger, F. Rininsland, G. C. Bazan and A. J. Heeger, Proc. Natl. Acad. Sci. U.S.A., 2002, 99, 49; N. DiCesare, M. R. Pinot, K. S. Schanze and J. R. Lakowicz, Langmuir, 2002, 18, 7785; D. T. McQuade, A. E. Pullen, T. M. Swager, Chem. Rev., 2000, 100, 2537. Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example

"comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other components.

It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

Above and below, unless stated otherwise percentages are percent by weight and temperatures are given in °C. The values of the dielectric constant ε ("permittivity") refer to values taken at 20°C and 1 ,000 Hz. The invention will now be described in more detail by reference to the following examples, which are illustrative only and do not limit the scope of the invention. Example 1

Bulk heterojunction organic photovoltaic devices for fullerene mixtures

Organic photovoltaic (OPV) devices are fabricated on pre-patterned ITO- glass substrates (13Q/sq.) purchased from LUMTEC Corporation.

Substrates are cleaned using common solvents (acetone, iso-propanol, deionized-water) in an ultrasonic bath. A layer of commercially available PV-E002 (Merck) was applied as a uniform coating by doctor blade at 80°C. The PV-E002 Films are then annealed at 100°C for 10 minutes in air and then transferred into a Nitrogen atmosphere. Active material solutions (i.e. polymer + fullerene) are prepared to fully dissolve the solutes at a 30 mg-cnrr³ solution concentration. Thin films are blade-coated in a nitrogen atmosphere to achieve active layer thicknesses between 50 and 800 nm as measured using a profilometer. A short drying period follows to ensure removal of any residual solvent

Typically, blade-coated films are dried between 70°C and 90°C for 2 minutes on a hotplate. Next the devices are transferred into an air atmosphere. On top of the active layer 0.9 ml_ of a conducting polymer poly(ethylene dioxythiophene) doped with poly(styrene sulfonic acid)

[PEDOT:PSS Clevios HTL Solar SCA 246-12 (Heraeus)] was spread and uniformly coated by spin-coating at 1100 rpm for 130 seconds. Afterwards Ag (100 nm) cathodes are thermally evaporated through a shadow mask to define the cells. For the last step of the device fabrication, the devices were each encapsulated with a glass cover slide using UV-curing epoxy glue.

Current-voltage characteristics are measured using a Keithley 2400 SMU while the solar cells are illuminated by a Newport Solar Simulator at 100 mW.cm^-2 white light. The solar simulator is equipped with AM1.5G filters. The illumination intensity is calibrated using a Si photodiode. All the device preparation and characterization is done in a dry-nitrogen atmosphere

Power conversion efficiency is calculated using the following expression oc x J sc x

η = where FF is defined as

pp _ V max x / max

The above devices were prepared using formulations containing a blend of Polymer 1 with the structure shown below and various fullerenes of prior art or the present invention. The formulation characteristics are shown in Table 1 below. The total solid concentration in the organic solution was 3 wt%. Polymer 1 and its preparation are disclosed in WO 2011/131280 A1.

Polymer 1

Table 1 : Formulation characteristics

Fullerene Ratio Ratio

No. Polymer 1 : Solvent Solvent 1:

Solvent 1

Fullerene 2 Solvent 2

C1 PCBM-Ceo 1.00:2.00 1MN

1 PCBC6-C60 1.00:2.00 1 MN

2 PCBC6-C60 1.00:2.00 1 N oXylene 75.0:25.0 Formulation C1 is a comparison example, containing fullerene PCBM-C60 wherein the ester substituent is butyric acid methyl ester, and which is not covered by formula F. Formulations 1 and 2 represent examples according to the present invention, containing the fullerene PCBC6-C60 wherein the ester substituent is butyric acid hexyl ester, and which is covered by formula F.

Initial device properties

BHJ OPV devices were prepared from these formulations and the OPV device characteristics were measured as described above.

Table 2 shows the device characteristics for the individual OPV devices comprising a photoactive layer with a BHJ formed from the active material (fullerene/polymer) solutions of Table 1.

Table 2: Photovoltaic cell characteristics after continuous simulated solar irradiation (AM1.5G)

It can be seen that the BHJs containing a fullerene of the present invention with an extended alkyl chain maintain increased device stability after 9 days of AM1.5G 1 sun simulated solar irradiation (Table 1 & 2).

Claims

Claims

A mixture comprising

a conjugated polymer comprising one or more units of formula 1 and one or more units of formula 2

and a substituted fullerene of formula F

wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings

R 13-18 H, straight-chain or branched alkyl with 1 to 30 C atoms, in which one or more CH2 groups are optionally replaced by -O- , -S-, -C(O)-, -C(S)-, -C(0)-O-, -O-C(O)-, -NR⁰-, -SiR°R⁰⁰-, - CF₂-, -CHR^CR⁰⁰-, -CY =CY²- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, CI or CN, a fullerene composed of n carbon atoms, optionally with one or more atoms trapped inside, o an integer > 1 or a non-integer > 1,

R¹ an alkyl group with 7 to 20 C atoms, which is straight-chain or branched, and in which one or more CH2 groups are optionally replaced by -0-, -S-, -C(=0)-, -C(=S)-, -C(=0)-0-, - 0-C(=O)-, -NR⁰-, -C(=0)-NR°-, -NR°-C(=O)-, -SiR⁰R⁰⁰-, -CF2- , -CR°=CR⁰⁰-, -CR°=N-, -N=N- or -C≡C- in such a manner that O and/or S atoms are not linked directly to one another, and/or in which one or more H atoms are optionally replaced by F, CI or CN,

Ar an aryl or heteroaryl group selected from formulae C1 to C9, which is optionally substituted by one or more identical or different groups L

(C2)

(C1) (C3)

(C4)

(C5) (C6)

(C7) (C8)

(C9) L F, CI, -CN, or an alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group, each of which has 1 to 20 C atoms and is optionally fluorinated,

R°, R⁰⁰ H or alkyl with 1 to 12 C-atoms,

Y¹, Y² H, F, CI or CN,

Ad an adduct, or a combination of adducts, appended to the fullerene Cn with any connectivity, m 0, an integer > , or a non-integer > 0.

2. The mixture of claim 1 , wherein n is 60 or 70.

3. The mixture according to claim 1 or 2, wherein m is 0 and o is 1 or 2. 4. The mixture according to any of claims 1 to 3, wherein R¹ in formula F denotes alkyl with 7 to 20 C atoms, in which one or more Chb groups are optionally replaced by -0-, -C(O)-, -C(0)-0- or -O-C(O)-, and in which one or more H atoms are optionally replaced by F. 5. The mixture according to any one of claims 1 to 4, wherein R¹ in formula F is selected from the following formulae:

R8

Jr

wherein the individual radicals have independently of each other the following meanings

0 or an integer from 1 to 15, with a+b >5, c, d, e 0 or an integer from 1 to 15, with c+d+e >4, f an integer from 6 to 15, g 0 or an integer from 1 to 15,

R¹¹ straight-chain or branched alkyl with 5 to 15 C atoms wherein one or more H atoms are optionally replaced by F, or, in case g> 5, R¹¹ may also denote H, F, CN or alkyl with 1 to 4 C atoms wherein one or more H atoms are optionally replaced by F.

The mixture according to any one of claims 1 to 5, wherein Ar in formula F is selected from formula C1 and C2, which are optionally substituted by one or more groups L as defined in claim 1.

The mixture according to any of claims 1 to 6, wherein the

compounds of formula F are selected from the following formulae

(PCBC6-C60)

(PCBC8-C60)

(PCBEH-C60)

8. The mixture according to any one of claims 1 to 5, wherein the conjugated polymer comprises, in addition to the units of formula 1 and 2, one or more units selected from the group consisting of the following formulae

wherein R¹¹ and R¹² are as defined in claim 1. 9. The mixture according to any one of claims 1 to 8, wherein the conjugated polymer comprises one or more units of the formula 1a and one or more units of the formula 2a

(D-Sp)- 1a (A-Sp)- 2a wherein D denotes a unit of formula 1 as defined in claim 1, A denotes a unit of formula 2 as defined in claim 1 , and Sp denotes a unit selected from formulae Sp1 to Sp16 as defined in claim 8.

10. The mixture according to any one of claims 1 to 9, wherein the conjugated polymer is of formula P

-[(D-Sp)x-(A-Sp)_y]n- P wherein A, D and Sp are as defined in claim 9, x denotes the molar fraction of the units (D-Sp), y denotes the molar fraction of the units (A- Sp), x and y are each, independently of one another > 0 and <1, with x+y=1 , and n is an integer >1.

11. The mixture according to any one of claims 1 to 11 , wherein the

conjugated polymer is selected from the following subformulae

wherein R ^{1 16}, x, y and n are as defined in claim 1 and 10.

The mixture according to any one of claims 1 to 11 , wherein R ¹ and R¹² in formulae Sp1 to Sp16, P1 and P2 are H, R¹³ and R¹⁴ in formula 1 , P1 and P2 are different from H, R¹⁵ and R¹⁶ in formula 1 , P1 and P2 are H, and R¹⁷ and R¹⁸ in formula 2, P1 and P2 are different from H.

The mixture according to any one of claims 1 to 12, wherein R¹¹, R¹², R¹³, R ⁴, R¹⁵, R¹⁶, R ⁷ and R¹⁸ in formulae 1 , 2, Sp1-Sp16, P1 and P2, when being different from H, are selected from the following groups: the group consisting of straight-chain or branched alkyl with 1 to 30, preferably 1 to 20, C atoms that is optionally fluorinated,

the group consisting of straight-chain or branched alkyl, alkoxy or sulfanylalkyl with 1 to 30, preferably 1 to 20, C atoms, and straight- chain or branched alkylcarbonyl, alkylcarbonyloxy or

alkyloxycarbonyl with 2 to 30, preferably 2 to 20, C atoms, each of the aforementioned groups being unsubstituted or substituted by one or more F atoms.

The mixture according to any one of claims 1 to 13, wherein the conjugated polymer is selected of formula PT

R³¹-chain-R³² PT wherein "chain" denotes a polymer chain selected of formula P, P1 or P2 as defined in claim 10 or 11 , and R³¹ and R³² have independently of each other one of the meanings of R ¹ as defined in claim 1 , or denote, independently of each other, H, F, Br, CI, I, -CH2CI, -CHO, -CR^CR^, - SiR'^'R'", -SiR'X'X", -SiR'R"X', -SnR'^'R'", -BR'R", -B(OR')(OR"), - B(OH)₂, -0-S02-R', -C≡CH, -C^C-SiR'a, -ZnX' or an endcap group, X' and X" denote halogen, R^*, R" and R"' have independently of each other one of the meanings of R° given in claim 1, and two of R', R" and R'" may also form a cyclosilyl, cyclostannyl, cycloborane or cycloboronate group with 2 to 20 C atoms together with the respective hetero atom to which they are attached.

15. A mixture according to any one of claims 1 to 14, further comprising one or more compounds which are selected from compounds having one or more of a semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting, photoactive and light emitting property.

16. A semiconducting, charge transport, electrically conducting,

photoconducting, photoactive, thermoelectric or light emitting

material, which comprises or consists of a mixture according to any one of claims 1 to 14.

17. Use of a mixture according to any one of claims 1 to 15 as

semiconducting, charge transport, electrically conducting,

photoconducting, photoactive, thermoelectric or light emitting material in an organic electronic (OE) device, or in a component of such an OE device, or in an assembly comprising such an OE device or such a component.

18. A formulation comprising a mixture according to any one of claims 1 to 15, and further comprising one or more solvents selected from organic solvents.

19. An OE device, or a component thereof, or an assembly comprising it, which is prepared using a formulation according to claim 18.

20. An OE device, or a component thereof, or an assembly comprising it, which comprises a mixture according to any one of claims 1 to 15 or a semiconducting, charge transport, electrically conducting, photoconducting, photoactive or light emitting material according to claim 16.

The OE device according to claim 20, which is an optical,

electrooptical, electronic, photoactive, electroluminescent or photoluminescent device.

The OE device according to claim 21, which is an organic field effect transistor (OFET), organic thin film transistor (OTFT), organic light emitting diode (OLED), organic light emitting transistor (OLET), organic photovoltaic device (OPV), organic photodetector (OPD), organic solar cell, dye sensitized solar cell (DSSC), perovskite based solar cell, laser diode, Schottky diode, photoconductor, photodetector or thermoelectric device.

23. The component according to claim 21 , which is a charge injection layer, charge transport layer, interlayer, planarising layer, antistatic film, polymer electrolyte membrane (PEM), conducting substrate or conducting pattern.

24. The assembly according to claim 21, which is an integrated circuit (IC), radio frequency identification (RFID) tag, security marking or security device, flat panel display, backlight, electrophotographic device, electrophotographic recording device, organic memory device, sensor device, biosensor or biochip.

25 The OE device according to claim 22, which is a bulk heterojunction (BHJ) OPV device, or an inverted BHJ OPV device.

26. A BHJ which comprises, or is being formed from, a mixture according to any one of claims 1 to 15.