WO2013052153A1

WO2013052153A1 - Blends of organic semiconductor compounds and electrically insulating amorphous polymers, methods and devices

Info

Publication number: WO2013052153A1
Application number: PCT/US2012/032559
Authority: WO
Inventors: Do Kyung Hwang; Bernard Kippelen; Lauren E. POLANDER; Raghunath R. DASARI; Seth R. Marder
Original assignee: Georgia Tech Research Corporation
Priority date: 2011-10-05
Filing date: 2012-04-06
Publication date: 2013-04-11

Abstract

Blends of selected organic semiconductor compounds with an electrically insulating, amorphous polymer matrix material which can be used in organic electronic devices including field-effect transistors. The organic semiconductor compound can have a molecular weight of 2,500 or less and can be a rylene compound such as a naphthalene diimide compound comprising a bridging moiety. Examples of bridging moieties include tetrazine and dithienopyrrole. The electrically insulating polymer can be organic polymer such as polystyrene or derivative thereof. The mobility remains high despite the blending with an insulating polymer. Good moisture and oxygen stability are observed.

Description

BLENDS OF ORGANIC SEMICONDUCTOR COMPOUNDS AND ELECTRICALLY INSULATING AMORPHOUS POLYMERS, METHODS AND DEVICES

BACKGROUND

Organic semiconductors are an important example of an electronic material which can be used in devices such as, for example, transistors, light emitting devices, photovoltaic devices, and sensors. Particularly important embodiments include organic semiconductors which can be processed at low cost from solution using methods such as, for example, ink jet printing. The morphology of the organic semiconductor is also an important aspect as this can determine important parameters such as charge carrier mobility. Stability to air (including oxygen and moisture) and thermal stability are further important characteristics.

When placed between electrodes to which an electrical bias is applied, some organic semiconductors with electron-donating properties (low ionization energy) can accept and transport primarily positive charges (holes), whereas other organic semiconductors with electron-attractive properties (high electron affinity) can accept and transport primarily negative charges (electrons). Still further, some organic semiconductors can be ambipolar materials, capable of accepting and transporting both positive and negative charges. In general, far more progress has been made in positive charge transporting materials than in negative charge transporting materials.

A review article is Shirota and Kageyama, Chem. Rev., 2007, 107, 953-1010.

A need exists to develop better organic semiconductor materials, particularly those which can accept and transport easily electrons and which are stable when exposed to oxygen and humidity. A balance of properties are needed including, for example, ease of solubility and processability, stability to ambient and electrical stressing, and high carrier mobility. Good performance and uniformity of transistors, including field-effect transistors, is particularly important including parameters such as high carrier mobility, high current on-off ratio, low and stable threshold voltage. In addition, a strong need exists to be able to carry out high throughput printing of circuits on flexible substrates. SUMMARY

Embodiments described herein include, for example, compounds,

compositions, devices, and methods of making and using the same.

One embodment provides, for example, a semiconducting blend comprising at least one electrically insulating and amorphous organic polymer and at least one organic semiconducting compound having a molecular weight below 2,500

wherein: moieties CI and C2 independently are chosen from polycyclic hydrocarbon moieties consisting of from 2 to 10 fused benzene rings, said benzene rings being independently from each other unsubstituted or substituted by one or more electron- withdrawing groups, Al, A2, A3, and A4 are independently chosen from a hydrogen atom, solubilizing groups and mixtures thereof, and hAr is a bridging moiety consisting of from 1 to 5 rings which are fused together and/or interconnected through at least one single bond, -CH=CH- bond, or -C≡C- bond, said rings being independently chosen from hydrocarbon rings and heterocyclic rings and said rings being independently from each other unsubstituted or substituted by one or more solubilizing groups or electron-withdrawing groups.

In other embodiments, moieties CI and C2 are independently chosen from unsubstituted naphthalene, unsubstituted perylene, unsubstituted coronene, naphthalene substituted by one or more electron-withdrawing groups, perylene substituted by one or more electron-withdrawing groups, and coronene substituted by one or more electron-withdrawing groups. In other embodiments, (i) the electron-withdrawing groups, if present, are, independently from each other, chosen from cyano, Ci-C₃₀ acyls, halogenos, C₁-C30 perhalogenocarbyls, C₁-C30 partially halogenated hydrocarbyls having a halogen atom over hydrogen atom molar ratio of at least 0.50 and mixtures thereof, and (ii) the solubilizing groups, if present, are, independently from each other, chosen from Ci- C₃₀ hydrocarbyls, Ci-C₃₀ partially halogenated hydrocarbyls having a halogen atom over hydrogen molar ratio below 0.50 and mixtures thereof.

In other embodiments, Al, A2, A3, and A4, independently, are a C₂-Ci₅ alkyl.

wherein

i) "a" is an integer 1, 2, 3, or 4;

ii) each X and X' is independently selected from O, S, Se, or NR⁶, wherein R⁶ is a C₁-C30 organic group independently selected from normal, branched, or cyclic alkyl, fluoroalkyl, aryl, heteroaryl, alkyl-aryl, and alkyl-heteroaryl groups optionally substituted with one or more fluoro, cyano, alkyl, alkoxy groups;

iii) each Y, Y', Y" and Y'" is independently selected from N, and CR⁷, where R⁷ is hydrogen, fluoro, or a C₁-C30 organic group independently selected from cyano, normal, branched, or cyclic alkyl, perfluoroalkyl, alkoxy, perfluoroalkoxy, aryl, heteroaryl, alkyl-aryl, and alkyl-heteroaryl groups, optionally substituted with one or more fluoride, cyano, alkyl, alkoxy groups;

iv) each Z and Z' is independently selected from 0, S, Se, C( ⁸)2, Si(R⁸)₂, NR⁸, (CO), (CO)₂ or C=C(CN)₂, wherein R⁸ is a C1-C30 organic group independently selected from normal, branched, or cyclic alkyl,

perfluoroalkyl, aryl, heteroaryl, alkyl-aryl, and alkyl-heteroaryl groups, optionally substituted with one or more fluoro, cyano, alkyl, alkoxy groups.

In other embodiments, the organic semiconducting compound is represented by.

wherein each R is independently selected from a hydrogen atom and electron- withdrawing groups, and each A is independently chosen from a hydrogen atom and solubilizing groups.

In other embodiments, the electrically insulating amorphous polymer and the organic semiconductor are soluble in a common organic solvent or mixture of solvents.

In other embodiments, the electrically insulating amorphous polymer is a homopolymer or copolymer selected from polymers of vinyl monomers bearing an optionally substituted aryl group, polymers of vinyl monomers bearing an optionally substituted cycloalkyi group, polymers comprising bicyclic repeat units derived from a cycloalkene, polymers comprising bicyclic repeat units derived from a

cycloalkadiene, polyalkylacrylar.es, polyalkylalkacrylar.es, polypropylenes,

polyurethanes, polyphenylene ethers, polyarylenes, polycarbonates, poly(aryl ether sulfone)s and polyetherimides. In other embodiments, more than 50 mol. % of the repeat units of the electrically insulating, amorphous polymer are repeat units R* of formula :

-CRaRb-CRc p- wherein R_a, Rb and R_c are independently chosen from a hydrogen atom, a halogen atom, and a C1-C30 organic group, and φ is optionally substituted phenyl.

In other embodiments, the electrically insulating amorphous polymer is a homopolymer with repeat units R** of formula

-CH₂-CHcp-

In other embodiments, the electrically insulating amorphous polymer is atactic. Atactic electrically insulating amorphous polymers in accordance with the present embodiments can be notably selected from the above cited electrically insulating amorphous polymers insofar as such polymers can be synthesized, and include, inter alia, atactic polymers of vinyl monomers bearing an optionally substituted aryl group (such as atactic polystyrene), atactic polymers of vinyl monomers bearing an optionally substituted cycloalkyl group and atactic polypropylene.

In other embodiments, the electrically insulating amorphous polymer has a number average degree of polymerization of at least 5,000, as determined by GPC using polystyrene calibration standards.

Other embodiments provide for the exception of a blend of

with poly(oc-methyl styrene).

Other embodiments provide a blend of

with poly(a-methyl styrene).

In other embodiments, the wt. % of the semiconductor organic compound is from about 10 wt.% to about 90 wt.% and the wt.% of the electrically insulating amorphous polymer is from about 10 wt.% to about 90 wt.%.

In other embodiments, the blend is free of dopant.

Other embodiments provide a method of making the semiconductor blend comprising mixing the organic semiconductor compound with the amorphous polymer in the presence of at least one common solvent and forming a solution with a solids content of at least 1% by weight.

Other embodiments provide a method of solution depositing films onto a substrate using the semiconductor blend.

Other embodiments provide a method of solution depositing patterned films by inkjet printing using the semiconductor blend.

Other embodiments provide an organic semi-conducting film, wherein the electrically insulating amorphous polymer forms the matrix of the blend and the organic semiconductor compound is at least partially phase-segregated from the matrix.

Other embodiments provide for an electronic device, which is a field-effect transistor, organic light emitting diode, photo-detector, sensor, photo-voltaic cell or memory device and comprising the semiconducting blend as described herein, or the semiconducting blend made by the methods described herein, or the film deposited by the methods described herein, or the films described herein.

Other embodiments provide for an n-channel field-effect transistor with an electron-mobility higher than 10^"2 cm²/V.sec comprising an organic semiconductor layer comprising the blends as described herein, or the blend made by methods described herein, or the film deposited by the methods as described herein, or the films as described herein, wherein the electrically insulating amorphous polymer has a field-effect electron mobility of less than 10^"6 cm²/V.sec and the organic

semiconductor compound has a field-effect electron mobility of at least 10^"2 cm²/V.sec. Alternatively, the electrically insulating amorphous polymer can have a field-effect electron mobility of less than 10^"7 cm²/V.sec, or the electrically insulating amorphous polymer can have a field-effect electron mobility of less than 10^"8 cm²/V.sec

At least one advantage for at least one embodiment includes good solution processing, especially for the preparation of organic electronic devices including organic field-effect transistors, including high throughput printing on large surface substrates with high homogeneity and device reproducibility. At least one additional advantage for at least some embodiments includes high carrier mobility, including electron transport mobility, even when blended with substantial amounts of polymer. At least one additional advantage for at least some embodiments includes good material stability in air and under electrical stressing. At least some additional advantages for at least some embodiments includes the ability to provide highly efficient n-channel field-effect transistors, in particular n-channel field-effect transistors exhibiting good stability in air and under electrical stressing.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates cross-sectional view of a transistor embodiment described in working example 1.

DETAILED DESCRIPTION

INTRODUCTION

All references cited herein are incorporated by reference in their entirety.

Description and examples of blends and transistors, as described herein, are also described in PCT application PCT/US2011/054989 filed October 5, 2011.

Organic semiconductor materials and applications, including transistors and field-effect transistors are described in Bao, Locklin, Organic Field-Effect Transistors, CRC Press, 2007, with particular note to pages 191-202 and the description of "N- Channel Organic Semiconductors" including imide compounds. Hole accepting and transporting semiconductors blended with polymers are described in J. Smith et al., Advanced Functional Materials, 2010, 20, 2330 and in Hwang et al., J. Mater. Chem., 2012, 22, 5531.

Doping of blends of organic semiconductors and amorphous polymers are described in U.S. provisional serial no. 61/582,037 filed December 30, 2011.

ORGANIC SEMICONDUCTING COMPOUND

Organic semiconductors, including ambipolar and electron transporting organic semiconductors, are known in the art.

The organic semiconductors can have a molecular weight of, for example, 2,500 g/mol or less, or 2,000 g/mol or less, or 1,500 g/mol or less, or 1,000 g/mol or less. Alternatively, the semiconductors can have a molecular weight of, for example, 500 g/mol to 2,500 g/mol, or 750 g/mol to 2,000 g/mol.

Organic semiconductors can comprise one or more rylene moieties, including two or more rylene moieties, and rylene moieties are known in the art. In another embodiment, the electron transport organic semiconductor comprises at least two rylene moieties which are the same and are linked by a bridging moiety.

In another embodiment, the organic semiconductor is represented by:

wherein Ryi and Ry₂ each represent independently of each other a rylene moiety and hAr is a bridging moiety representing a single bond or representing a moiety comprising at least one aryl or heteroaryl ring.

One embodiment provides, for example, at least one organic semiconducting compound having a molecular weight below 2,500 represented by formula (I):

wherein :

the moieties CI and C2 (including the surrounding circles in the symbol of I) are independently chosen from polycyclic hydrocarbon moieties consisting of from 2 to 10 fused benzene rings, said benzene rings being independently from each other unsubstituted or substituted by one or more electron-withdrawing groups,

Al, A2, A3, and A4, at each occurrence, is independently chosen from a hydrogen atom, solubilizing groups and mixtures thereof, and

hAr is a bridging moiety consisting of from 1 to 5 rings which are fused together and/or interconnected through at least one single bond, -CH=CH- bond or -C≡ C- bond, said rings being independently chosen from hydrocarbon rings and heterocyclic rings and said rings being independently from each other unsubstituted or substituted by one or more solubilizing groups or electron-withdrawing groups.

In one embodiment, each © (CI or C2) is independently chosen from unsubstituted naphthalene, unsubstituted perylene, unsubstituted coronene, naphthalene substituted by one or more electron-withdrawing groups, perylene substituted by one or more electron-withdrawing groups, and coronene substituted by one or more electron-withdrawing groups.

In one embodiment, (i) the monovalent electron-withdrawing groups, if present, are, independently from each other, chosen from cyano, C1-C30 acyls, halogenos, C1-C30 perhalogenocarbyls, C1-C30 partially halogenated hydrocarbyls having a halogen atom over hydrogen atom molar ratio of at least 0.50 and mixtures thereof, and (ii) the monovalent solubilizing groups, if present, are, independently from each other, chosen from C1-C30 hydrocarbyls, C1-C30 partially halogenated hydrocarbyls having a halogen atom over hydrogen molar ratio below 0.50 and mixtures thereof.

In one embodiment, Al, A2, A3, and A4, at each occurrence, is a C2-C₁₅ a Compounds can include the following:

"NDI-hAr-NDI" wherein hAr is a bridging moiety comprising at least one aryl or heteroaryl ring and the rylene at each end is a naphthalene diimide compound (as described in US provisional application serial no. 61/475,888 filed April 15, 2011). The R², R³, and R⁴ groups are typically independently selected terminal substituent groups for ring carbon atoms of the NDI groups. They can be, for example, hydrogen or electron- withdrawing groups. The R², R³, and R⁴ groups can be independently selected from hydrogen, halide, or a C1-C30 , C1-C20, or C1-C12 organic group, such as for example independently selected cyano, normal, branched, or cyclic alkyl, fluoroalkyl, aryl, heteroaryl, alkyl-aryl, acyl- and alkyl-heteroaryl groups, optionally substituted with one or more fluoro, cyano, alkyl, alkoxy groups. Variation of the R², R³, and R⁴ groups can also be used to "tune" the electronic characteristics of the NDI groups, as well as the solubility, solution processability, and solid state properties of the final resulting compounds.

Each R¹ and R¹ group can be an independently selected terminal substituent organic group for the nitrogen atoms of the NDI groups described herein, although in many embodiments, R¹ and R¹ can be the same terminal group. Variation of the R¹ and/or R¹ groups can be used to "tune" the electronic characteristics of the NDI or PDI groups, as well as the solubility, solution processability, and solid state properties of the final resulting oligomeric compounds. R¹ and R¹ can potentially be any organic group that is chemically, thermally, and electrochemically stable under the conditions of operation of an OFET device containing the compounds, but are often selected from a normal, branched, or cyclic alkyl, aryl, heteroaryl, alkyl-aryl, or alkyl-heteroaryl group optionally substituted with one or more halide, cyano, alkyl, or alkoxy groups. In many embodiments, R¹ and R¹ can be normal, branched, or cyclic alkyl or perfluoroalkyl groups.

The R², R³, and R⁴ groups are typically independently selected terminal substituent groups for ring carbon atoms of the NDI groups. The R², R³, and R⁴ groups can be independently selected from hydrogen, halide, or a C1-C30 , Ci-C₂o, or C1-C12 organic group, such as for example independently selected cyano, normal, branched, or cyclic alkyl, fluoroalkyl, aryl, heteroaryl, alkyl-aryl, acyl- and alkyl- heteroaryl groups, optionally substituted with one or more fluoro, cyano, alkyl, alkoxy groups. Variation of the R², R³, and R⁴ groups can also be used to "tune" the electronic characteristics of the NDI groups, as well as the solubility, solution processability, and solid state properties of the final resulting compounds.

In many embodiments of the NDI-hAr-NDI oligomers, R⁴ which is near the bridging "hAr" heteroaryl groups, is hydrogen, a halogen, or another sterically small and undemanding group, so as minimize unfavorable steric interactions with the bridging hAr groups, which could inhibit the ability of the NDI and bridging hAr groups to adopt coplanar or nearly coplanar conformations that maximize electronic conjugation between the NDI and bridging hAr groups. In many embodiments, R², R³, and R⁴ are independently selected from hydrogen, fluoro and cyano groups. In many embodiments, the R¹ groups are the same, R⁴ is hydrogen, and the point of attachment to the hAr ring relative to the R² and R³ groups is the same in both NDI groups, as shown in the diagram below:

In such compounds, R³ is a favored point of attachment for an electron withdrawing substituent, such as fluoride, cyano, or trifluoroalkyi groups, which can desirably lower the energy of the Lowest Unoccupied Molecular Orbital (LUMO) of the NDI groups and/or the oligomers, and increase the air stability of the resulting compounds.

The brid ing moiety, hAr, can be represented by one of the following:

wherein i) each X and X' is independently selected from 0, S, Se, or NR⁵, wherein R⁵ is a terminal organic group;

ii) each Y, Y', Y" and Y'" is independently selected from N, and CR⁷, where R⁷ is hydrogen, halide, or a terminal organic group;

iii) each Z and Z" is independently selected from 0, S, Se, C(R⁸)₂, Si(R⁸)₂, NR⁸, (CO), (CO)₂ or C=C(CN)₂, wherein R⁸ is a terminal organic group.

In particular, bridging groups which comprise a tetrazine or a dithienopyrrole moiety can be used, as exemplified below in the working examples. The bridging groups can also comprise a combination of tetrazine and thiophene moieties as illustrated in the working examples below.

In one embodiment, the rylene moiety can be represented by general formula

II:

(Π)

wherein © (C2 as illustrated in II) is a polycyclic hydrocarbon moiety consisting of from 2 to 20 fused benzene rings, which are optionally substituted by one or more monovalent electron-withdrawing groups; and A3 and A4 is independently chosen from a hydrogen atom, monovalent solubilizing groups and mixtures thereof. The structure illustrated in formula II can be monovalent, and the monovalent linkage cite to the rest of the molecule can be adapted by the synthetic availability.

The group © can be, for example, naphthalene, perylene, coronene and mixtures thereof, and can be optionally substituted by one or more monovalent electron-withdrawing groups.

The rylene group can be, for example, represented by general formula III, general formula IV, general formula V, general formula VI and mixtures thereof,

f ormula III f ormula IV

f ormula V f ormula VI

wherein m=0, 1 or 2; m'=0, 1 or 2; m"=0, 1 or 2; m"'=0, 1 or 2; and wherein X, at each occurrence, is independently chosen from a hydrogen atom, monovalent electron-withdrawing groups and mixtures thereof. The Y structure can be, for example, independently chosen from a hydrogen atom, monovalent solubilizing groups and mixtures thereof. The structures illustrated in formulae III, IV, V, and VI can be monovalent, and the monovalent linkage site to the rest of the molecule can be adapted based on synthetic availability.

In one embodiment, the rylene can be represented by the general formula III with m = 0, such as a radical of formula VII:

wherein Y' represents a monovalent solubilizing group. Structure VII can be monovalent and linked to the hAr group, and the monovalent linkage site can be adapted based on the synthetic availability.

Other rylene embodiments can be represented by formula VIII, formula IX, formula X, and/or formula XI :

(VIII) (IX) (X) (XI) wherein X' is a monovalent electron- withdrawing group and Y' is a monovalent solubilizing group or hydrogen. Structures VIII, IX, X, and XI can be monovalent and linked in a variety of ways to an hAr group based on synthetic availability. The monovalent electron-withdrawing groups can be, independently from each other, chosen from, for example, cyano, Ci-Ceo acyls, halogenos, C1-C60 perhalogenocarbyls, C1-C60 partially halogenated hydrocarbyls having a halogen atom over hydrogen atom molar ratio of at least 0.50, and mixtures thereof.

In another embodiment, the polycyclic hydrocarbon moiety is not substituted by any monovalent electron-withdrawing group.

The monovalent solubilizing groups can be, independently from each other, chosen from, for example, Ci-C₆o hydrocarbyls, Ci-C₆o partially halogenated hydrocarbyls having a halogen atom over hydrogen molar ratio below 0.50 and mixtures thereof.

The groups A, R, Y or Y', at each occurrence, which are bound to the imide nitrogen can be a monovalent solubilizing group as known in the art, which, when the compound is dissolved in a solvent chosen from chloroform, chlorobenzene and THF, at a temperature of 25°C, increases the solubility of the compound at least 10%, when compared to the solubility of a reference compound identical to said compound except that the monovalent solubilizing group of the occurrence of concern is replaced by a hydrogen atom. In one embodiment, A, R, Y or Y', at each occurrence, can be a -C30 alkyl to facilitate solubility.

ELECTRICALLY INSULATING AND AMORPHOUS ORGANIC POLYMER

Polymers which are electrically insulating and amorphous are known in the art and can be blended with the organic semiconductor compound. The polymer can serve as a matrix. Examples can be found in, for example, WO 2005/055248 or US patent publication 2007/0102696 (Avecia); see also WO 03/030278. Polymers can be homopolymers or copolymers.

The amorphous nature of the polymer can be assessed by any suitable technique known by those skilled in the art. Very often, it is measured by

Differential Scanning Calorimetry, using for example a Universal V3.7A Instruments DSC calorimeter. For this purpose, it is preliminarily checked that the calorimeter is well-calibrated by means of a calibration sample. Then, the polymer of which the amorphous nature is to be verified is submitted to the following heating/cooling

St

cycle : 1 heating from room temperature (about 23°C) up to T_max ⁰C at a rate of 10°C/min_/ followed by cooling from T_max °C down to room temperature at a rate of

20°C/min, followed by 2^nd heating from room temperature up to T_max ⁰C at a rate of 10°C/min. Semi-crystalline polymers, which are not amorphous, present in general an endothermic first-order transition that appears as a negative peak on the DSC scan, while amorphous polymers present in general no or essentially no endothermic first-order transition appearing as a peak on the DSC scan. The choice of T_max is not critical, provided T_max is set to a sufficiently high value, not to miss a possible endothermic first-order transition that would appear as a peak on the DSC scan at a very high temperature; however, T_max should obviously not exceed the

decomposition temperature of the polymer, and should preferably be lower than said decomposition temperature by at least 20°C. As commonly known to the skilled person, the choice of T_max depends on the nature of the polymer, and can be easily made based on common knowledge and/or a simple trial-and-error process. While in some cases a small peak can be detected for amorphous polymers in accordance with the present embodiments, the enthalpy of fusion should be less than, for example, 30 J/g, or less than 20 J/g, or less than 10 J/g. The degree of crystallinity can be, for example, less than 10%, or less than 5%, or less than 1%, as measured by methods known in the art.

The glass transition of the amorphous polymer can be assessed by any suitable technique known by the skilled person. Conveniently, it is also determined by Differential Scanning Calorimetry, using the same method and equipment as previously detailed for the determination of the amorphous nature of the polymer. The glass transition of the amorphous polymer is advantageously made by a tangential construction procedure on the heat flow curve by constructing a first tangent line to the curve above the transition region and a second tangent line to the curve below the transition region. The temperature on the curve halfway between these tangent lines is the glass transition temperature. Glass transition temperature is known in the art. See, for example, (1) "Glass Transition

Temperatures of Polymers," Andrews, Grulke, Polymer Handbook, 4^h Ed., VI-193 - VI-253, and (2) Encyclopedia of Polymer Science and Engineering, Vol. 2, "Glass Transition," 655-677 (Bicerano). The electrically insulating organic polymers generally are known in the art. They are advantageously free of, or essentially free of, or substantially free of, charge carriers; besides, they are advantageously free of, or essentially free of, or substantially free of, charge carrier traps. They can show, for example, a field-effect charge carrier mobility of < 10^"6 cm²/V.sec. in addition, a conductivity value, o, can be less than 10^"6 S/cm, or less than 10^"8 S/cm.

In addition, the electrically insulating polymer can be a dielectric material and can have low permittivity, ε, at 1,000 Hz of 3.3 or less. The polymer matrix preferably has a permittivity at 1,000 Hz of less than 3.0, more preferably 2.9 or less. Preferably the organic matrix has a permittivity at 1,000 Hz of greater than 1.7. It is especially preferred that the permittivity of the matrix is in the range from 2.0 to 2.9. While not wishing to be bound by any particular theory it is believed that possibly the use of matrices with a permittivity of greater than 3.3 at 1,000 Hz, may lead to a reduction in the OSC layer mobility in an electronic device, for example an OFET. In addition, high permittivity matrices could also result in increased current hysteresis of the device, which is undesirable.

Examples of amorphous polymers are described below, including

homopolymers and copolymers:

(1) Polymers of vinyl monomers bearing an optionally substituted aryl or an optionally substituted cycloalkyl group:

In general, more than 50 wt. % of the recurring units of these polymers are recurring units R of one or more formulae :

wherein: Ri, R₂ and R₃ independently represent a hydrogen atom, a halogen atom or an alkyl group, and A represents an optionally substituted aryl or an optionally substituted cycloalkyl group. Ri, R₂ and R3 are preferably chosen from a hydrogen atom and a methyl group. Very preferably, Ri and R₂ represent a hydrogen atom. Very preferably, R3 represents a hydrogen atom or a methyl group. Group A represents preferably a phenyl group, a naphthyl group, a p-biphenyl group or a C₄-Cs cycloalkyl group, such as cyclohexyl. Still more preferably, A represents a phenyl group or a cyclohexyl group.

Group A can represent an unsubstituted aryl group or an unsubstituted cycloalkyl group. Alternatively, the aryl group or the cycloaliphatic group can substituted by at least one substituting group. The substituting group is

advantageously chosen from (s-1) alkyls, (s-2) cycloalkyls, (s-3) aryls, (s-4) alkylaryls, (s-5) aralkyls, (s-6) alkenyls, (s-7) halogens, (s-8) the partially

halogenated homologous of radicals (s-1), (s-2), (s-3), (s-4), (s-5) and (s-6), and (s- 9) the perhalogenated homologous of radicals (s-1), (s-2), (s-3), (s-4), (s-5) and (s- 6).

Good results can be obtained with polystyrenes, in particular with polystyrene homopolymers. The polystyrene can be a homo- or copolymer of which more than 50 wt. % of the recurring units are recurring units R** of formula :

- CH₂ - CHcp - wherein φ represents a phenyl group. Atactic polystyrenes are preferred.

Good results can also be obtained with poly(a-methyl)styrenes, in particular with poly(a-methyl)styrene homopolymers. A poly(a-methyl)styrene can be intended to denote any homo- or copolymer of which more than 50 wt. % of the recurring units are recurring units R*** of formula :

- CH₂ - C(CH₃) p - wherein φ represents a phenyl group.

In addition, polyvinylcyclohexanes can be used, in particular

polyvinylcyclohexane homopolymers. A polyvinylcyclohexane can be any homo- or copolymer of which more than 50 wt. % of the recurring units are recurring units R**** of formula :

- CH₂ - CH(c-hex) - wherein (c-hex) represents a cyclohexyl group.

(2) Polyalkylacrylar.es and polyalkylalkacrylar.es

Among these polymers, it can be, for example, cited polymethylacrylate homo- and copolymers, polycyclohexylacrylate homo- and copolymers,

polymethylmethacrylate homo- and copolymers, and polycyclohexylmethacrylate homo- and copolymers.

(3) Polymers comprising bicyclic repeat units derived from a cycloalkene

Among these polymers, it can be, for example, cited polymers comprising bicyclic repeat units of at least one formula selected from

and (bicyclic repeat unit derived from norbornene monomer).

Copolymers comprising -CH₂-CH2- repeat units and bicyclic repeat units of at least one of the above shown formulae, such as ethylene-norbornene copolymers, may be preferred.

(4) Polyurethane homo- and copolymers

(5) Polyphenylene ethers, homo- and copolymers.

(6) Polyarylene homopolymers and copolymers, in particular polyphenylene homopolymers and copolymers, very particularly, kinked rigid-rod polyphenylenes.

A polyarylene can be any polymer of which more than 50 wt. % of the recurring units are recurring units Rl, wherein: (a) the recurring units Rl are of one or more formulae consisting of an optionally substituted arylene group, and (b) the optionally substituted arylene groups of which the recurring units Rl consist, are linked by each of their two ends to two other optionally substituted arylene groups via a direct C-C linkage.

That the optionally substituted arylene groups are linked by each of their two ends to two other optionally substituted arylene groups via a direct C-C linkage, is an essential feature of the recurring units Rl; thus, if present in a polyarylene, arylene recurring units which are linked by at least one of their two ends to a group other than an arylene group such as phenylene recurring units cpi, φ₂ and φ₂' below :

- 0 - cpi - S(=0)₂ - ,

- 0 - φ₂ - φ₂' - 0 - are not recurring units Rl in the sense of the present invention.

The optionally substituted arylene group is preferably chosen from optionally substituted phenylenes, i.e. the polyarylene is a polyphenylene; the polyphenylene includes preferably optionally substituted p-phenylene recurring units and optionally substituted m-phenylene recurring units. The optionally substituted arylene group contained may be unsubstituted; alternatively, the optionally substituted arylene group may be substituted by at least one substituting group. The substituting group is advantageously a solubilizing group. A solubilizing group is a group, as known in the art, which increases the solubility of the polyarylene in at least one organic solvent, in particular in at least one of dimethylformamide, N-methylpyrrolidinone, hexamethylphosphoric triamide, benzene, tetrahydrofuran and dimethoxyethane. The substituting group is also advantageously a group which increases the fusibility of the polyarylene, i.e. it lowers its glass transition temperature and its melt viscosity. Preferably, the monovalent substituting group is chosen

from hydrocarbylketones [-C(=0)-R, where R is a hydrocarbyl group] and

hydrocarbyloxyhydrocarby I ketones [-C(=0)-Ri-0-R₂, where Ri is a divalent hydrocarbon group and R₂ is a hydrocarbyl group], said hydrocarbylketones and hydrocarbyloxyhydrocarby I ketones being themselves unsubstituted or substituted by at least one of the above listed monovalent substituting groups.

The polyarylene also can be a kinked rigid-rod polyphenylene copolymer of which essentially all, when not all, the recurring units consist of a mix of p- phenylene substituted by a solubilizing group (such as a phenylketone group) with unsubstituted m-phenylene, in a mole ratio p-phenylene: m-phenylene of from 10:90 to 70:30, preferably of from 25:75 to 65:35, more preferably of from 35:65 to 60:40, still more preferably of from 45:55 to 55:45, and most preferably of about 50:50. Such a kinked rigid-rod polyphenylene copolymer is commercially available from Solvay Specialty Polymers as PrimoSpire^® PR-250 polyphenylene. The polyarylene has generally a number average molecular weight greater than 1,000, preferably greater than 10,000. On the other hand, its number average molecular weight is generally below 100,000. The number average molecular weight of a polyarylene is advantageously determined by: (1) measuring a "relative" number average molecular weight of the polyarylene by Gel Permeation

Chromatography (GPC) using polystyrene calibration standards, then (2) dividing the so-measured "relative" number average molecular weight by a factor 2. It is proceeded accordingly because the skilled in the art who is a specialist of

polyarylenes knows that their "relative" number average molecular weight, as measured by GPC, are generally off by a factor of about 2 times ; it has already been accounted for this correction factor in all the above cited lower and upper limits of molecular weight.

(7) Polycarbonate homopolymers and copolymers, in particular aromatic

polycarbonate homopolymers and copolymers.

A polycarbonate can denote any polymer of which more than 50 wt. % of the recurring units are recurring units R2 comprising at least one carbonate group (-0- C(=0)-0-), while an aromatic polycarbonate is intended to denote any polymer of which more than 50 wt. % of the recurring units are recurring units R2 further comprising, in addition to the at least one carbonate group (-0-C(=0)-0-), at least one optionally substituted arylene group. The optionally substituted arylene is preferably chosen from optionally substituted phenylenes and optionally substituted naphthylenes. The optionally substituted arylene group contained may be

unsubstituted; alternatively, the optionally substituted arylene group may be substituted by at least one substituting group. The substituting group is

halogenated homologous of radicals (s-1), (s-2), (s-3), (s-4), (s-5) and (s-6), and (s- 9) the perhalogenated homologous of radicals (s-1), (s-2), (s-3), (s-4), (s-5) and (s- 6). The recurring units R2 may be chosen from recurring units obtainable by the polycondensation reaction of phosgene and at least one aromatic diol :

CI - C(=0) - CI + OH - p - OH ^ - O - C(=0) - O - p - Phosgene + diol -> recurring unit R2 wherein, p can be, for example, a C6-C50 divalent radical.

Suitable polycarbonates are available on the market. For instance,

LEXAN^®104 polycarbonate is a bisphenol A polycarbonate, commercially available from General Electric. A branched polycarbonate such as Makrolon 1239, available from Bayer Material Science LLC, can also be used.

(8) Polyfaryl ether sulfone s, including homopolymers and copolymers

A poly(aryl ether sulfone) can be any polymer of which more than 50 wt. % of the recurring units are recurring units R3 of one ore more formulae comprising at least one arylene group, at least one ether group (-0-) and at least one sulfone group [-S(=0)₂ -]. Certain preferred poly(aryl ether sulfone)s are known by the skilled person as "polyphenylsulfone" (PPSU), "polyethersulfone" (PES) and

"polysulfone" (PSU).

A polyphenylsulfone (PPSU) can be used which is any polymer, including homopolymers and copolymers, of which more than 50 wt. % of the recurring units

A polyethersulfone (PESU) can be any polymer of which more than 50 wt.

of formula :

PESU homo- and copolymers can be used.

A polysulfone (PSU), sometimes also named bisphenol A polysulfone, is any polymer of which more than 50 wt. % of the recurring units are recurring units R3'"

PSU homo- and copolymers can be used.

(9) Polyetherimides, including polyetherimide homopolymers and copolymers These are polymers of which more than 50 wt. % of the recurring units are recurring units R4 comprising at least one ether group (-0-) and at least one imide group, such as

AND/OR IN ITS AMIC ACID FORM

Aromatic polyetherimides may be preferred. In aromatic polyetherimides, the recurring units R4 futher comprise at least one optionally substituted arylene group, such as unsubstituted p-phenylene. Good results can be obtained with polymers the recurring units of which are of formula, for example,

and/or their two corresponding amic acid forms. Such polymers are commercially available respectively as AURUM® from MITSUI, and as ULTEM® from SABIC.

In one embodiment, the electrically insulating amorphous polymer is selected from optionally substituted homo- and copolymers of vinylphenyls, homo- and copolymers of alkylacrylates, copolymers of ethylene and bicyclic norbornene, polycarbonates, polysulfones, polyethersulfones.

In one embodiment, the polymer is an organic polymer which is soluble in at least one organic solvent, including a solvent or mixture of solvents for which the organic semiconductor compound is also soluble (a common solvent or solvent mixture).

In one embodiment, more than 50 mol. % of the repeat units of the electrically insulating, amorphous polymer are repeat units R* of formula:

-CRaRb-CRc p- wherein R_a, R_b and R_c are independently chosen from a hydrogen atom, a halogen atom, and a C1-C30 organic group, and φ is optionally substituted phenyl.

In one embodiment, the electrically insulating amorphous polymer is a homopolymer, generally an atactic homopolymer, with repeat units R** of formula

-CH₂-CHcp-

In one embodiment, the electrically insulating amorphous polymer is a homopolymer with repeat units R*** of formula

-CH₂-C(CH₃) p-

In one embodiment, the electrically insulating amorphous polymer has a number average degree of polymerization of at least 5,000, as determined by GPC using polystyrene calibration standards.

Examples of suitable polymer matrices are atactic polystyrene and derivatives of polystyrene such as poly(a-alkyl styrenes). Further examples are given below.

The polymer matrix should preferably be capable of forming a film, more preferably a flexible film. Polymers of styrene and alpha-methyl styrene, for example copolymers including styrene, alpha-methylstyrene and butadiene may suitably be used.

Matrices of low permittivity of use herein have advantageously few permanent dipoles which could otherwise lead to random fluctuations in molecular site energies and/or could otherwise act as traps slowing down or even inhibiting charge transport. Matrices of low permittivity of use in the present invention are preferably free, or essentially free, or substantially free, of permanent dipoles which could otherwise lead to random fluctuations in molecular site energies and/or could otherwise act as traps slowing down or even inhibiting charge transport. The permittivity (dielectric constant) can be determined by the ASTM D150 test method. It is also preferred that matrices are used which have solubility parameters with low polar and hydrogen bonding contributions as materials of this type have low permanent dipoles. The three dimensional solubility parameters include:

dispersive, polar, and hydrogen bonding components (C. M. Hansen, Ind. Eng. and Chem., Prod. Res. and Devi., 9, No 3, p 282., 1970). These parameters may be determined empirically or calculated from known molar group contributions as described In Handbook of Solubility Parameters and Other Cohesion Parameters ed. A. F. M. Barton, CRC Press, 1991. The solubility parameters of many known polymers are also listed in this publication.

It is desirable that the permittivity of the matrix has little dependence on frequency. This is typical of non-polar materials.

Polymers and/or copolymers can be chosen as the matrix by the permittivity of their substituent groups. A list of low polarity matrices suitable for use include, for example, polyolefins including, for example, polystyrene, 2,5 poly(alpha- methylstyrene), 2,6 poly(alpha-vinylnaphthalene), and the like.

Copolymers containing the repeat units of the above polymers are also suitable as matrices. Copolymers offer the possibility of improving compatibility with the semiconductor, modifying the morphology and/or the glass transition

temperature of the final layer composition. Both random or block copolymers can be used. It is also possible to add some more polar monomer components as long as the overall composition remains low in polarity.

Preferred insulating matrices for use in the organic semiconductor layer formulation include polystyrene [especially, atactic polystyrene], poly(alpha- methylstyrene), polyvinylcinnamate, poly(4-vinylbiphenyl), and poly(4- methylstyrene) [especially, atactic poly(4-methylstyrene)].

Glass transition temperature is known in the art. See, for example, (1) "Glass Transition Temperatures of Polymers," Andrews, Grulke, Polymer Handbook, 4^h Ed., VI- 193 - VI-253, and (2) Encyclopedia of Polymer Science and Engineering, Vol. 2, "Glass Transition," 655-677 (Bicerano). Usually, the amorphous polymer has a glass transition temperature higher, or even much higher, than the room temperature (23°C); its glass transition temperature is preferably higher than 75°C, and very preferably higher than 100°C. No particular upper limit for the glass transition temperature is present, but the polymer can have a glass transition temperature of less than about 300°C, or less than 250°C, or less than 200°C, or less than 150°C.

EXCLUSION OR EXCEPTION EMBODIMENTS

If desired, embodiments described in PCT application PCT/US2011/054989 filed October 5, 2011 can be excluded. For example, in some embodiments, the blend is not inclusive of:

with poly(a-methyl styrene); or in other embodiments, the blend is not inclusive of:

with poly(a-methyl styrene).

COMPONENT AMOUNTS

The amounts of the electrically insulating amorphous polymer and the organic semiconductor compound in the blend can be varied for the particular materials, processing conditions, and application needs. For example, the amount of each, whether polymer or organic semiconductor compound, can be 10 wt.% to 90 wt.%, or 20 wt.% to 80 wt.%, or 25 wt.% to 75 wt.%, or 30 wt.% to 70 wt.%, or 40 wt.% to 60 wt.%.

PROPERTIES OF THE COMPOSITIONS

As demonstrated in the below working examples, the blend can have a mobility which is at least as high as or even higher than the mobility of the organic compound. For example, the blend mobility can be, for example, at least 50%, or at least 75%, or at least 90% of the mobility of the mobility of the organic compound. In some cases, the blend mobility can be, for example, about 25% or less, or about 10% or less, of the mobility of the mobility of the organic compound.

Dopants can be used, as desired, but in one embodiment, the blend is substantially free of or totally free of dopant. For example, the amount of dopant can be less than 1 wt.%, or less than 0.1 wt.%, or less than 0.01 wt.%, or less than 0.001 wt.%.

BLEND MORPHOLOGY

While not limited by theory, it is possible that the organic semiconductor compound can vertically segregate, order itself, and/or crystallize. See, for example, Hwang et al., J. Mater. Chem., 2012, 22, 5531 and characterization methods described therein.

METHODS OF MAKING

Methods are known in the art for blending components and at least one electron transport semiconductor can be mixed with at least one polymer matrix material. For example, the organic semiconductor compound can be dissolved in a solvent; the electrically insulating amorphous polymer can be also dissolved in a solvent, and the solutions can be mixed.

One embodiment provides a method of making the semiconductor blend according to any one of the embodiments described herein comprising mixing the organic semiconductor compound with the electrically insulating amorphous polymer in the presence of at least one comment solvent and forming a solution with a solids content of at least 1 wt.%, such as for example, 1% by weight to 10% by weight. INKS

The blend compositions can be formulated with one or more solvents to form an ink.

Examples of solvents include organic solvents including halogenated solvents and non-halogenated solvents. Examples include 1,4-dioxane, 1,1,1,2- tetrachloroethane, dichlorobenzene, and mesitylene-tetralin.

The concentration of solids in the ink can be, for example, at least 1 mg/mL, or at least 10 mg/mL, or at least 100 mg/mL, or at least 200 mg/mL.

Inks can be deposited onto rigid and/or flexible substrates by methods known in the art. Polymer or plastic substrates can be used including glassy or flexible polymers.

Patterning can be carried out, if desired. Inkjet printing can be carried out. DEVICES

Organic electronic devices are known in the art and include transistors (including field-effect transistors and circuits comprising transistors), OLEDs, photovoltaics, and sensors.

One device example is the top gate OFET.

Some embodiments, therefore, provide for an electronic device, which is a field-effect transistor, organic light emitting diode, photo-detector, sensor, photovoltaic cell or memory device, and comprising the semiconducting blend, as described herein.

Other embodiments provide, for example, a n-channel field-effect transistor with an electron-mobility higher than 10^"2 cm² / V.sec comprising an organic semiconductor layer comprising the blends as described herein, wherein the electrically insulating amorphous polymer has a field-effect electron mobility of less than 10^"6 cm² / V.sec and the organic semi-conductor compound has a field-effect electron mobility of at least 10^"2 cm² / V.sec.

WORKING EXAMPLES Additional embodiments are provided in the following non-limiting working examples.

Exam le 1 (DRR-IV-209n)

The preparation of this compound can be found in US provisional application 61/475,888 filed April 15, 2011.

Fabrication

OFETs with bottom contact and top gate structure were fabricated on glass substrates (Corning, Eagle 2000). Au (50 nm) bottom contact source/drain electrodes were deposited by thermal evaporation through a shadow mask. Organic semiconductor layers of DRR-IV-209n and DRR-IV-209n/polystyrene (PS) (A _w 390 kDa) blend (1:1 ratio) were formed on the substrates by spin coating with a solution prepared from dichlorobenzene (20 mg/mL) at 500 rpm for 10 sec and at 2,000 rpm for 20 sec. Then, samples were annealed at 120 °C for 10 min in a N₂-filled dry box. CYTOP (45 nm)/AI₂O₃ (50 nm) layers were used as top-gate dielectrics. CYTOP solution (CTL-809M) was purchased from Asahi Glass with a concentration of 9 wt. %. To deposit the 45 nm-thick CYTOP layers, the original solution diluted with their solvents (CT-solv.180) to have solution :solvent ratios of 1:3.5. The 45 nm-thick CYTOP layers were deposited by spin casting at 3000 rpm for 60 sec. The CYTOP (45 nm) films were annealed at 100 °C for 20 min. All spin coating and annealing processes were carried out in a N₂-filled dry box. Then, the AI₂O₃ dielectric films (50 nm) were deposited on top of the CYTOP layer using a Savannah 100 ALD system from Cambridge Nanotech Inc. Films were grown at 110 °C using alternating exposures of trimethyl aluminum [AI(CH₃)₃] and H₂0 vapor at a deposition rate of approximately 0.1 nm per cycle. Finally, Al (150 nm) gate electrodes were deposited by thermal evaporation through a shadow mask.

The device is illustrated in Figure 1.

Electrical characterization

The electrical characterization of the OFETs was carried out in a N₂-filled glove box (0₂, H₂0 < 0.1 ppm). Current-voltage (I-V) characteristics of OFETs were measured with an Agilent E5272A source/monitor unit. Field-effect mobility in the saturation regime was calculated from the slope of the [drain current IDS) I n versus l/ffi plo nsistor equation:

where Q_n is the capacitance per unit area of the gate dielectric [F/cm²], and W (width) and L (length) are the dimensions of the semiconductor channel defined by the source/drain electrodes of the transistor.

Transistor Performance Results:

Transfer characteristics were measured. W/L = 2,550 microns/180 microns. V_DS = 15 V.

Output characteristics were measured. W/L = 2,550 microns/180 microns. V_GS = 0 to 15 V. Step = 3 V.

□ Table I: DRR-IV-209 and DRR-IV-209n/PS blend OFETs

(ave. 8 dev.) Example 2, COMPARATIVE (LEP-III-055e)

The preparation of this compound can be found in US provisional application 61/579,608 filed December 22, 2011.

Fabrication

OFETs with bottom contact and top gate structure were fabricated on glass substrates (Corning, Eagle 2000). Au (50 nm) bottom contact source/drain electrodes were deposited by thermal evaporation through a shadow mask. Organic semiconductor layers of LEP-III-055e and LEP-III-055e/polystyrene (PS) (A _w 390 kDa) blend (1: 1 ratio) were formed on the substrates by spin coating with a solution prepared from tetrachloroethane (15 mg/mL) at 500 rpm for 10 sec and at 2,000 rpm for 20 sec. Then, samples were annealed at 100 °C for 10 min in a N₂-filled dry box. CYTOP (45 nm)/AI₂O3 (50 nm) layers were used as top-gate dielectrics. CYTOP solution (CTL-809M) was purchased from Asahi Glass with a concentration of 9 wt. %. To deposit the 45 nm-thick CYTOP layers, the original solution diluted with their solvents (CT-solv.180) to have solution :solvent ratios of 1:3.5. The 45 nm-thick CYTOP layers were deposited by spin casting at 3000 rpm for 60 sec. The CYTOP (45 nm) films were annealed at 100 °C for 20 min. All spin coating and annealing processes were carried out in a N₂-filled dry box. Then, the AI₂O3 dielectric films (50 nm) were deposited on top of the CYTOP layer using a Savannah 100 ALD system from Cambridge Nanotech Inc. Films were grown at 110 °C using alternating exposures of trimethyl aluminum [AI(CH₃)₃] and H₂O vapor at a deposition rate of approximately 0.1 nm per cycle. Finally, Al (150 nm) gate electrodes were deposited by thermal evaporation through a shadow mask. The device was substantially analogous to the device shown in Figure 1 except for the different semiconductor component.

Electrical characterization

The electrical characterization of the OFETs was carried out in a N₂-filled glove box (0_2/ H₂0 < 0.1 ppm). Current-voltage (I-V) characteristics of OFETs were measured with an Agilent E5272A source/monitor unit. Field-effect mobility in the saturation regime was calculated from the slope of the |drain current {IDS) In versus l cs plo nsistor equation:

Output characteristics were measured. W/L = 2,550 microns/180 microns. V_GS = 0 to 15 V. Step = 3 V. -III-055e and LEP-III-055e/PS blend OFETs

055e/PS blend μηη

Example 3 (LEH-III-119a)

Fabrication

OFETs with bottom contact and top gate structure were fabricated on glass substrates (Corning, Eagle 2000). Au (50 nm) bottom contact source/drain

electrodes were deposited by thermal evaporation through a shadow mask. Organic semiconductor layers of LEH-III-119a and LEH-III-119a/poly(a-methyl styrene) (PaMS) (M_w 100 kDa) blend (1: 1 ratio) were formed on the substrates by spin coating with a solution prepared from dichlorobenzene (30 mg/ml_) at 500 rpm for 10 sec and at 2,000 rpm for 20 sec. Then, samples were annealed at 100 °C for 15 min in a N₂-filled dry box. CYTOP (45 nm)/AI₂O₃ (50 nm) layers were used as top- gate dielectrics. CYTOP solution (CTL-809M) was purchased from Asahi Glass with a concentration of 9 wt. %. To deposit the 45 nm-thick CYTOP layers, the original solution diluted with their solvents (CT-solv.180) to have solution: solvent ratios of 1:3.5. The 45 nm-thick CYTOP layers were deposited by spin casting at 3000 rpm for 60 sec. The CYTOP (45 nm) films were annealed at 100 °C for 20 min. All spin coating and annealing processes were carried out in a N₂-filled dry box. Then, the AI₂O3 dielectric films (50 nm) were deposited on top of the CYTOP layer using a Savannah 100 ALD system from Cambridge Nanotech Inc. Films were grown at 110 °C using alternating exposures of trimethyl aluminum [AI(CH₃)3] and H₂O vapor at a deposition rate of approximately 0.1 nm per cycle. Finally, Al (150 nm) gate electrodes were deposited by thermal evaporation through a shadow mask.

The device was substantially analogous to the device shown in Figure 1 except for the different semiconductor component.

Electrical characterization

The electrical characterization of the OFETs was carried out in a N₂-filled glove box (O₂, H₂O < 0.1 ppm). Current-voltage (I-V) characteristics of OFETs were measured with an Agilent E5272A source/monitor unit. Field-effect mobility in the saturation regime was calculated from the slope of the [drain current (I_Ds) \^1/2 versus V_GS pl nsistor equation:

Transfer characteristics were measured, n-mode. W/L = 6,050 microns/180 microns. V_DS = 25 V. V_TH = 14.1 V. μ = 0.8 cm²/Vs.

Output characteristics were measured, n-mode. W/L = 6,050 microns/180 microns. V_GS = 0 to 25 V. Step = 2.5 V.

Transfer characteristics were measured, p-mode. V_Ds = -25 V. W/L = 6,050 microns/180 microns. V_TH = -11.7 V. μ = 6.3 X 10^"3 cm²/Vs.

Output characteristics were measured, p-mode. W/L = 6,050 microns/180 microns. V_GS = 0 to -25 V. Step = 2.5 V.

Table III. Ambipolar: n-mode and p-mode operation.

LEH-III-119a and LEH-III-119a/PaMS blend OFETs

Sample Type Mode W/L _n^₂ ^Solvent ele mde V (^cm2/^Vs) ^ ^(V)

Ambipolar 6050μΓη/180μΓη _dich|oroben_Zene Au 0.7 ±0.1 14.8±0.8

(n-mode) (ave. 4 dev.)

SPT-II-57i LEH-III-119a =

Ambipolar 6050um/180pm _l ^ . 7.5 (±1.0) -12.4

(p-mode) (ave. 4 dev ) ³⁴'⁸ d^!chlorobenzene Au ^ _{±Q ?}

L LEbHH- IiIiIi- (n^m-m^biPode)! ⁶^ (av⁰e^μ.™ 4^/1 d⁸e⁰v^μ.)™ 34.8 dichlorobenzene Au 0.5 ±0.1 10.2±1.4

SPT-II-57j 119a/PaMS

blend Ambipolar 6050μηι/180μπι _dichloroben_Zene Au ^{23 (} "⁵⁾ -6.1 ±0.9

(p-mode) (ave. 4 dev.) x 10"3

Stability testing was also carried out with the following results:

Table IV: Ambient stability of LEH-III-119a and LEH-III-119a/PaMS blend OFETs (n-mode)

S/D Cm^'

Sample Type Ambient exposure W/L

electrode μ (crri2/vs) I

(nF/cm²) m 00

Pristine 6050pm/180pm Au 34.8 0.79 14.3

5 days in air 6050pm/180pm Au 34.8 0.67 15.1

SPT-II-57i LEH-III-119a

17 days in air 6050pm/180pm Au 34.8 0.43 17.1

18 hrs vacuum

annealing at 100 6050pm/180pm Au 34.8 0.51 17.0

OC

Pristine 6050pm/180pm Au 34.8 0.84 12.8

5 days in air 6050pm/180pm Au 34.8 0.55 13.8

LEH-III-

SPT-II-57j 119a/PaMS

blend 17 days in air 6050pm/180pm Au 34.8 0.42 16.7

18 hrs vacuum

annealing at 100 6050pm/180pm Au 34.8 0.65 14.9

OC

Claims

WHAT IS CLAIMED IS:

1. A semiconducting blend comprising at least one electrically insulating and amorphous organic polymer and at least one organic semiconducting compound having a molecular weight below 2,500 represented by formula (I):

(I) wherein :

moieties CI and C2 independently are chosen from polycyclic hydrocarbon moieties consisting of from 2 to 10 fused benzene rings, said benzene rings being independently from each other unsubstituted or substituted by one or more electron- withdrawing groups,

Al, A2, A3, and A4 are independently chosen from a hydrogen atom, solubilizing groups and mixtures thereof, and

hAr is a bridging moiety consisting of from 1 to 5 rings which are fused together and/or interconnected through at least one single bond, -CH=CH- bond, or -C≡C- bond, said rings being independently chosen from hydrocarbon rings and heterocyclic rings and said rings being independently from each other unsubstituted or substituted by one or more solubilizing groups or electron-withdrawing groups.

2. The semiconducting blend according to claim 1, wherein moieties CI and C2 are independently chosen from unsubstituted naphthalene, unsubstituted perylene, unsubstituted coronene, naphthalene substituted by one or more electron- withdrawing groups, perylene substituted by one or more electron-withdrawing groups, and coronene substituted by one or more electron-withdrawing groups.

3. The semiconducting blend according to claim 1 or 2, wherein:

(i) the electron-withdrawing groups, if present, are, independently from each other, chosen from cyano, Ci-C3o acyls, halogenos, C1-C30 perhalogenocarbyls, C1-C30 partially halogenated hydrocarbyls having a halogen atom over hydrogen atom molar ratio of at least 0.50 and mixtures thereof, and

(ii) the solubilizing groups, if present, are, independently from each other, chosen from Ci-C₃₀ hydrocarbyls, C1-C30 partially halogenated hydrocarbyls having a halogen atom over hydrogen molar ratio below 0.50 and mixtures thereof.

4. The semiconducting blend according to anyone of the preceding claims, wherein Al, A2, A3, and A4, independently, are a C2-C₁₅ alkyl.

5. The semiconducting blend according to anyone of the preceding claims, wherein hAr is represented by:

wherein

v) "a is an integer 1, 2, 3, or 4; vi) each X and X' is independently selected from 0, S, Se, or NR⁶, wherein R⁶ is a C1-C30 organic group independently selected from normal, branched, or cyclic alkyl, fluoroalkyl, aryl, heteroaryl, alkyl-aryl, and alkyl-heteroaryl groups optionally substituted with one or more fluoro, cyano, alkyl, alkoxy groups;

vii) each Y, Y', Y" and Y'" is independently selected from N, and CR⁷, where R⁷ is hydrogen, fluoro, or a C1-C30 organic group independently selected from cyano, normal, branched, or cyclic alkyl, perfluoroalkyl, alkoxy, perfluoroalkoxy, aryl, heteroaryl, alkyl-aryl, and alkyl-heteroaryl groups, optionally substituted with one or more fluoride, cyano, alkyl, alkoxy groups;

viii) each Z and Z' is independently selected from 0, S, Se, C(R⁸)₂, Si(R⁸)₂, NR⁸, (CO), (CO)₂ or C=C(CN)₂, wherein R⁸ is a C1-C30 organic group independently selected from normal, branched, or cyclic alkyl,

6. The semiconducting blend according to any one of the preceding claims wherein the organic semiconducting compound is represented by:

7. The semiconducting blend according to any one of the preceding claims, wherein the electrically insulating amorphous polymer and the organic semiconductor are soluble in a common organic solvent or mixture of solvents.

8. The semi-conducting blend according to any of the preceding claims, wherein the electrically insulating amorphous polymer is a homopolymer or copolymer selected from polymers of vinyl monomers bearing an optionally substituted aryl group, polymers of vinyl monomers bearing an optionally substituted cycloalkyl group, polymers comprising bicyclic repeat units derived from a cycloalkene, polymers comprising bicyclic repeat units derived from a cycloalkadiene, polyalkylacrylar.es, polyalkylalkacrylar.es, polypropylenes, polyurethanes, polyphenylene ether, polyarylenes, polycarbonates, poly(aryl ether sulfone)s and polyetherimides.

9. The semiconducting blend according to any one of the preceding claims, wherein more than 50 mol. % of the repeat units of the electrically insulating, amorphous polymer are repeat units R* of formula :

-CR_aR_b-CR_c p- wherein R_a, Rb and R_c are independently chosen from a hydrogen atom, a halogen atom, and a C1-C30 organic group, and φ is optionally substituted phenyl.

10. The semi-conducting blend according to claim 9, wherein the electrically insulating amorphous polymer is an atactic homopolymer with repeat units R** of formula

-CH₂-CHcp-

11. The semiconducting blend according to any one of the preceding claims, wherein the electrically insulating amorphous polymer has a number average degree of polymerization of at least 5,000, as determined by GPC using polystyrene calibration standards.

12. The semiconducting blend according to any one of the preceding claims, with the exception of a blend of

with poly(oc-methyl styrene).

13. The semi-conducting blend according to any of claims 1 to 7 and 11, which is a blend of

with poly(oc-methyl styrene).

14. The semiconductor blend of any of the preceding claims, wherein the wt. % of the semiconductor organic compound is from about 10 wt.% to about 90 wt.% and the wt.% of the electrically insulating amorphous polymer is from about 10 wt.% to about 90 wt.%.

15. The semi-conductor blend of any of the preceding claims, which is free of dopant.

16. A method of making the semi-conductor blend according to any of the preceding claims comprising mixing the organic semiconductor compound with the amorphous polymer in the presence of at least one common solvent and forming a solution with a solids content of at least 1% by weight.

17. A method of solution depositing films onto a substrate using the semiconductor blend according to any of claims 1-15 or made by the method of claim 16.

18. A method of solution depositing patterned films by inkjet printing using the semiconductor blend according to any of claims 1-15 or made by the method of claim 16.

19. An organic semi-conducting film made by the method according to claim 17 or 18, wherein the electrically insulating amorphous polymer forms the matrix of the blend and the organic semiconductor compound is at least partially phase- segregated from the matrix.

20. An electronic device, which is a field-effect transistor, organic light emitting diode, photo-detector, sensor, photo-voltaic cell or memory device and comprising the semiconducting blend according to any one of claims 1-15 or the semiconducting blend made by the method according to claim 16, or the film deposited by the method according to claim 17 or 18, or the film according to claim 19.

21. An n-channel field-effect transistor with an electron-mobility higher than 10^"2 cm²/V.sec comprising an organic semiconductor layer comprising the blend of any of claims 1-15, or the blend made by the method of claim 16, or the film deposited by the method according to claim 17 or 18, or the film according to claim 19, wherein the electrically insulating amorphous polymer has a field-effect electron mobility of less than 10^"6 cm²/V.sec and the organic semiconductor compound has a field-effect electron mobility of at least 10^"2 cm²/V.sec.