PROCESS FOR PREPARING A CRYSTALLINE ORGANIC SEMICONDUCTOR MATERIAL

Abstract

Provided are a process for preparing a crystalline organic semiconductor material wherein the conditions of crystallization lead to the formation of crystals at the gas liquid interface having advantageous semiconductor properties, the obtained crystalline organic semiconductor material and the use thereof for the production of organic semiconductor devices, in particular organic field effect transistors and organic solar cells.

Claims

1: A process for preparing a crystalline organic semiconductor material, the process comprising (a) providing a solution of at least one organic semiconductor A) in a solvent (L1) or in a solvent mixture comprising at least one solvent (L1), wherein the solvent (L1) has a boiling point at 1013.25 mbar of at least 140° C., a viscosity of at least 1.2 mPas at 23° C., and a surface tension of at least 31.5 mN/m at 200° C., and (b) applying said solution to a surface of a substrate to allow evaporation of the solvent or solvent mixture and crystallization of the organic semiconductor A).

2: The process according to claim 1, wherein the crystallization of the organic semiconductor A) proceeds from a gas liquid interface.

3: The process according to claim 1, wherein after (a), no additional component is added to the solution to effect crystallization of the organic semiconductor A).

4: The process according to claim 1, wherein a crystalline organic semiconductor material obtained in (b) has an area of larger than 10×10 μm.sup.2, and an average thickness of at most 0.1 μm.

5: The process according to claim 1, wherein the solvent (L1) or the solvent mixture comprising a solvent (L1) in (a) a has a boiling point at 1013.25 mbar of at least 150° C.

6: The process according to claim 1, wherein the solvent (L1) has a viscosity in the range of 1.3 to 1000 mPas at 23° C.

7: The process according to claim 1, wherein the solvent (L1) has a surface tension in the range of 32 to 65 mN/m at 20° C.

8: The process according to claim 11, wherein the organic semiconductor A) has a solubility in the solvent (L1) or in the solvent mixture comprising the solvent (L1) in (a) at 20° C. of at least 0.01 mg/ml.

9: The process according to claim 1, wherein the solvent in the solution in (a) consists only of the solvent (L1).

10: The process according to claim 1, wherein the solvent mixture is used in (a), which is a mixture of the at least one solvent (L1) and at least one solvent (L2) different from (L1).

11: The process according to claim 10, wherein an amount of the solvent (L1) in the solvent mixture is in a range of from 1 to 99% by weight based on a total weight of the solvent mixture.

12: The process according to claim 1, wherein the solvent (L1) is selected from the group consisting of L1.1) a compound that is liquid at 20° C. and 1013 mbar and is represented by formula (I)
R.sup.c—X.sup.1-A-X.sup.2—R.sup.d   (I)  wherein A is a 5- to 8-membered unsubstituted or substituted, aliphatic or aromatic carbocycle or heterocycle, X.sup.1 and X.sup.2 are independently *—(C═O)—O—, *—(CH.sub.2).sub.m—O— or *—(CH.sub.2).sub.m—O—(C═O)—, where * is a point of linkage to the aliphatic or aromatic carbocycle or heterocycle, and m is 0, 1, or 2, and R.sup.c and R.sup.d are independently unbranched or branched C.sub.1-C.sub.12-alkyl or C.sub.2-C.sub.12-alkenyl; L1.2) an alkyl benzoate; L1.3) a hydroxybenzoic acid ester; L1.4) an alkylene carbonate; L1.5) an aromatic aliphatic ketone; L1.6) dimethylsulfoxide (DMSO); L1.7) N-methylpyrrolidone; L1.8) a polycyclic hydrocarbon comprising a cycloaliphatic ring; L1.9) a dichlorobenzene; and a mixture thereof.

13: The process according to claim 12, wherein the solvent (L1) is the compound of the formula (I) (L1.1) and is at least one compound of formulae (I.1), (I.2), (I.3), (I.4) and (I.5) ##STR00091## wherein X.sup.1 and X.sup.2 are independently *—(C═O)—O—, *—(CH.sub.2).sub.m—O— or *—(CH.sub.2).sub.m—O—(C═O)—, where * is a point of linkage to the aliphatic or aromatic carbocycle or heterocycle, and m is 0, 1, or 2; and R.sup.c and R.sup.d are independently unbranched or branched C.sub.1-C.sub.12-alkyl or C.sub.2-C.sub.12-alkenyl.

14: The process according to claim 13, where in the formulae (I.1), (I.2), (I.3), (I.4) and (I.5), R.sup.c and R.sup.d are independently methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, tert.-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, isononyl, isodecyl, 2-propylheptyl, n-undecyl, or isoundecyl.

15: The process according to claim 13, where in the formulae (I.1), (I.2), (I.3), (I.4) and (I.5), the X.sup.1 and X.sup.2 are both *—(C═O)—O—.

16: The process according to claim 1, wherein the solvent (L1) is selected from the group consisting of dimethylphthalate, diethylphthalate, di(n-propyl)phthalate, di(n-butyl)phthalate, diallylphthalate, dimethyl sulfate, ethyl benzoate, ethyl salicylate, acetophenone, propylene carbonate, N-methylpyrrolidone, tetralin, 1,2-dichlorobenzene, and a mixture thereof.

17: The process according to claim 10, wherein the at least one solvent (L2) is selected from the group consisting of an aliphatic, a cycloaliphatic or an aromatic hydrocarbon other than a polycyclic hydrocarbon comprising a cycloaliphatic ring, an aromatic ether, an open chain aliphatic ether, a polyether, a ether alcohol, or a cyclic ether, a ketone other than an aromatic aliphatic ketone, an ester other than an alkyl benzoate, a hydroxybenzoic acid ester, and an alkylene carbonate, an aliphatic or a cycloaliphatic alcohol, a benzene based alcohol, a halogenated aromatic compound, a thiophenol or an alkylthio-substituted benzene, an aromatic compound comprising a phenyl group fused to a 5-, 6-, or 7-membered cycloheteroalkyl group, a 5-membered heteroaryl compound or a benzo-fused 5-membered heteroaryl compound, an aromatic carboxylic acid, an aromatic aldehyde, a trifluoromethyl-substituted benzene compound, a cyano-substituted or isocyano-substituted benzene compound, a nitro-substituted benzene compound, a phenyl sulfone, a 6-membered heteroaryl compound or a benzofused 6-membered heteroaryl compound, a 5-membered heteroaryl compound or a benzofused 5-membered heteroaryl compound, an aprotic polar solvent other than dimethylsulfoxide and N-methylpyrrolidone, and a mixture thereof.

18: The process according to claim 1, wherein the at least one organic semiconductor A) is selected from the group consisting of a rylene compound of formula (II.a) ##STR00092## wherein n is 1, 2, 3 or 4, R.sup.a and R.sup.b are independently hydrogen, or an unsubstituted or a substituted alkyl, alkenyl, alkadienyl, alkynyl, cycloalkyl, bicycloalkyl, cycloalkenyl, heterocycloalkyl, aryl or heteroaryl, R.sup.n1, R.sup.n2, R.sup.n4 are independently hydrogen, F, Cl, Br, I, CN, hydroxy, mercapto, nitro, cyanato, thiocyanato, formyl, acyl, carboxy, carboxylate, alkylcarbonyloxy, carbamoyl, alkylaminocarbonyl, dialkylaminocarbonyl, sulfo, sulfonate, sulfoamino, sulfamoyl, alkylsulfonyl, arylsulfonyl, amidino, NE.sup.1E.sup.2, where E.sup.1 and E.sup.2 are each independently hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl, an unsubstituted or a substituted alkyl, alkoxy, alkylthio, (monoalkyl)amino, (dialkyl)amino, cycloalkyl, cycloalkoxy, cycloalkylthio, (monocycloalkyl)amino, (dicycloalkyl)amino, heterocycloalkyl, heterocycloalkoxy, heterocycloalkylthio, (monoheterocycloalkyl)amino, (diheterocycloalkyl)amino, aryl, aryloxy, arylthio, (monoaryl)amino, (diaryl)amino, hetaryl, hetaryloxy, hetarylthio, (monohetaryl)amino or (dihetaryl)amino; a compound of formula (II.b) ##STR00093## wherein R.sup.1b and R.sup.2b are independently hydrogen or an unsubstituted or a substituted linear C.sub.1-C.sub.30-alkyl, branched C.sub.3-C.sub.30-alkyl, linear C.sub.2-C.sub.30-alkenyl, branched C.sub.3-C.sub.30-alkenyl, linear C.sub.2-C.sub.30-alkynyl, branched C.sub.4-C.sub.30-alkynyl, cycloalkyl, aryl or hetaryl, Y.sup.1b and Y.sup.2b are independently O, S, Se or NR.sup.3b, where R.sup.3b is independently hydrogen or an unsubstituted or a substituted alkyl, cycloalkyl or aryl; a compound of formula (II.c) ##STR00094## wherein R.sup.1c and R.sup.2c are independently hydrogen or an unsubstituted or a substituted linear C.sub.1-C.sub.30-alkyl, branched C.sub.3-C.sub.30-alkyl, linear C.sub.2-C.sub.30-alkenyl, branched C.sub.3-C.sub.30-alkenyl, linear C.sub.2-C.sub.30-alkynyl, branched C.sub.4-C.sub.30-alkynyl, cycloalkyl, aryl or hetaryl, Y.sup.1c, Y.sup.2c and Y.sup.3c are independently O, S, Se or NR.sup.3c, where R.sup.3c is independently hydrogen or an unsubstituted or a substituted alkyl, cycloalkyl or an aryl; a compound of formula (II.d) ##STR00095## wherein R.sup.1d and R.sup.2d are independently hydrogen, or an unsubstituted or a substituted linear C.sub.1-C.sub.30-alkyl, branched C.sub.3-C.sub.30-alkyl, linear C.sub.2-C.sub.30-alkenyl, branched C.sub.3-C.sub.30-alkenyl, linear C.sub.2-C.sub.30-alkynyl, branched C.sub.4-C.sub.30alkynyl, cycloalkyl, aryl or hetaryl, Y.sup.1d, Y.sup.2d, Y.sup.3d and Y.sup.4d are independently O, S, Se or NR.sup.3d, where R.sup.3d is independently hydrogen or an unsubstituted or a substituted alkyl, cycloalkyl or aryl; and a compound of formula (II.e) ##STR00096## wherein R.sup.1e and R.sup.2e are independently hydrogen, or an unsubstituted or a substituted linear C.sub.1-C.sub.30-alkyl, branched C.sub.3-C.sub.30-alkyl, linear C.sub.2-C.sub.30-alkenyl, branched C.sub.3-C.sub.30-alkenyl, linear C.sub.2-C.sub.30-alkynyl, branched C.sub.4-C.sub.30-alkynyl, cycloalkyl, aryl or hetaryl, Y.sup.1c and Y.sup.2e are independently O, S, Se or NR.sup.3e, where R.sup.3e is independently hydrogen, or an unsubstituted or a substituted alkyl, cycloalkyl or aryl.

19: The process according to claim 18, wherein the at least one organic semiconductor A) is the rylene compound of the formula (II.a), and R.sup.a and R.sup.b are independently hydrogen, linear C.sub.1-C.sub.30-alkyl, branched C.sub.3-C.sub.30-alkyl, perfluoro-C.sub.1-C.sub.30-alkyl, 1H,1H-perfluoro-C.sub.2-C.sub.30-alkyl, 1H,1H,2H,2H-perfluoro-C.sub.3-C.sub.30-alkyl, a radical of the formula G.1, a radical of formula G.2 or a radical of formula G.3 ##STR00097## where # represents a bonding side to a nitrogen atom, B where present, is a C.sub.1-C.sub.10-alkylene group which is optionally interrupted by one or more nonadjacent groups which are —O— or —S—, y is 0 or 1, R.sup.m is independently C.sub.1-C.sub.30-alkyl, C.sub.1-C.sub.30-fluoroalkyl, fluorine, chlorine, bromine, NE.sup.3E.sup.4, nitro or cyano, where E.sup.3 and E.sup.4 are independently hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl, R.sup.n is independently a C.sub.1-C.sub.30-alkyl, and x in formulae G.2 and G.3 is 1, 2, 3, 4 or 5.

20: The process according to claim 18, wherein the at least one organic semiconductor A) is the rylene compound of the formula (II.a), and R.sup.a and R.sup.b are independently a radical of formula (III.1), (III.2) or (III.3) ##STR00098## wherein # is a bonding site, and in the formula (III.1) R.sup.a and R.sup.f are independently C.sub.1- to C.sub.27-alkyl, where a sum of carbon atoms of R.sup.a and R.sup.f is an integer of from to 28, in the formula (III.2) R.sup.g and R.sup.h are independently C.sub.1- to C.sub.28-alkyl, where a sum of carbon atoms of R.sup.g and R.sup.h is an integer of from to 29, in the formula (III.3) R.sup.i, R.sup.k and R.sup.l are independently C.sub.1- to C.sub.27-alkyl, where a sum of carbon atoms of R.sup.i, R.sup.k and R.sup.l is an integer of from 3 to 29.

21: The process according to claim 18, wherein the at least one organic semiconductor A) is the rylene compound of the formula (II.a), and R.sup.a and R.sup.b are the same.

22: The process according to claim 1, wherein the at least one organic semiconductor A) is a compound of formula (I.a2) ##STR00099## wherein R.sup.a and R.sup.b are independently hydrogen, or an unsubstituted or a substituted alkyl, alkenyl, alkadienyl, alkynyl, cycloalkyl, bicycloalkyl, cycloalkenyl, heterocycloalkyl, aryl or heteroaryl, R.sup.12 and R.sup.23 are independently F, Cl, Br, CN, and R.sup.11, R.sup.13, R.sup.14, R.sup.21, R.sup.22 and R.sup.24 are hydrogen.

23: A crystalline organic semiconductor material, obtained by the process according to claim 1.

24: A method for producing a semiconductor material, the method comprising: preparing the semiconductor material from the crystalline organic semiconductor material according to claim 23.

25: A process for preparing a device or a sensor, the process comprising: (a) providing a solution of at least one organic semiconductor A) in a solvent (L1) or in a solvent mixture comprising the solvent (L1), wherein the solvent (L1) has a boiling point at 1013.25 mbar of at least 140° C., a viscosity of at least 1.2 mPas at 23° C., and a surface tension of at least 31.5 mN/m at 20° C., and (b) applying said solution to a surface of a substrate to allow evaporation of the solvent or solvent mixture and crystallization of the organic semiconductor A), wherein the substrate in b) is a substrate of the device, or wherein crystals of the organic semiconductor A) obtained in b) are transferred to the device or the sensor, and wherein the device is an electronic device, an optical device, or an optoelectronic device.

26: The process according to claim 25, wherein (b) is performed by printing.

27: The process according to claim 25, wherein the device is an organic field-effect transistor, a electroluminescent arrangement, an organic solar cell or a photodetector.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0686] FIG. 1 shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A1) from a mixture of DMP:Toluene (1:3) (example 1).

[0687] FIG. 2 shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A1) from acetylacetone (comparative example 2).

[0688] FIG. 3 shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A1) from toluene (comparative example 3).

[0689] FIG. 4a shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A9) from DMP (example 48.1). The black bar at the left bottom of the image shows a distance of 50 μm.

[0690] FIG. 4b shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A9) from EthAc (comparative example 48.4). The black bar at the left bottom of the image shows a distance of 50 μm.

[0691] FIG. 5a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution (example 52) with U.sub.GS=−20 V to +50 V with U.sub.DS=50 V

[0692] FIG. 5b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution (example 52) with U.sub.DS=0 V to +45V with U.sub.GS=15, 30, 45 and 60V.

[0693] FIG. 6a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP:Acac (1:9) solution (example 53) with U.sub.GS=−30 V to +60 V with U.sub.DS=20 V

[0694] FIG. 6b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP:Acac (1:9) solution (example 53) with U.sub.DS=0 V to +20 V with U.sub.GS=0, 15, 30, 45 and 60V.

[0695] FIG. 7a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a wafer with a 30 nm insulating dielectric layer of Al.sub.2O.sub.3(example 54) with U.sub.GS=−2 V to +10 V with U.sub.DS=5 V.

[0696] FIG. 7b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a wafer with a 30 nm insulating dielectric layer of Al.sub.2O.sub.3(example 54) with U.sub.DS=0 V to +10 V with U.sub.GS=5, 7.5 and 10 V.

[0697] FIG. 8a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a wafer after surface modification with 4-ethoxyphenylphosphonic acid (example 55) with U.sub.GS=+2 V to +15 V with U.sub.DS=10V

[0698] FIG. 8b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a wafer after surface modification with 4-ethoxyphenylphosphonic acid (example 55) with U.sub.DS=0 V to +10 V with U.sub.GS=9, 12 and 15 V.

[0699] FIG. 9a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a polyethylene terephthalate foil as substrate (example 56) with U.sub.GS=−20 V to +60 V with U.sub.DS=40 V.

[0700] FIG. 9b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a polyethylene terephthalate foil as substrate (example 56) with U.sub.DS=0 V to +60 V with U.sub.GS=15, 30, 45 and 60 V.

[0701] FIG. 10a shows the transfer characteristics of the semiconductor obtained by inkjet printing of compound A1) from a DMP solution onto a SiO.sub.2 wafer (example 57) with U.sub.GS=−20 V to +50 V with U.sub.DS=50 V.

[0702] FIG. 10b shows the output characteristics of the semiconductor obtained by inkjet printing of compound A1) from a DMP solution onto a SiO.sub.2 wafer (example 57) with U.sub.DS=0 V to +50 V with U.sub.GS=20, 30, 40 and 50 V.

[0703] FIG. 11a shows the transfer characteristics of the semiconductor obtained by inkjet printing of compound A1) from a DMP solution onto an Al.sub.2O.sub.3 wafer after surface modification (example 58) with U.sub.GS=+2 V to +15 V with U.sub.DS=10 V.

[0704] FIG. 11b shows the output characteristics of the semiconductor obtained by inkjet printing of compound A1) from a DMP solution onto an Al.sub.2O.sub.3 wafer after surface modification (example 58) with U.sub.DS=0 V to +10 V with U.sub.GS=12 and 15 V.

[0705] FIG. 12a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a SiO.sub.2 wafer using a poly(methyl methacrylate)/trimethylolpropane triacrylate bottom gate dielectric (example 59) with U.sub.GS=−10 V to +50 V with U.sub.DS=40 V.

[0706] FIG. 12b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP solution onto a SiO.sub.2 wafer using a poly(methyl methacrylate)/trimethylolpropane triacrylate bottom gate dielectric (example 59) with U.sub.DS=0 V to +40 V with U.sub.GS=10, 20, 30, 40 and 50 V.

[0707] FIG. 13a shows the transfer characteristics of the semiconductor obtained by inkjet printing of compound A3) from a DMP solution onto a wafer with a 30 nm insulating dielectric layer of Al.sub.2O.sub.3(example 60) with U.sub.GS=−30 V to +60 V with U.sub.DS=50 V.

[0708] FIG. 13b shows the transfer characteristics of the semiconductor obtained by inkjet printing of compound A3) from a DMP solution onto a wafer with a 30 nm insulating dielectric layer of Al.sub.2O.sub.3(example 60) with U.sub.GS=−30 V to +60 V with U.sub.DS=50 V.

[0709] FIG. 14a shows the transfer characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP:Toluene (1:3) solution (example 63) with U.sub.GS=−2 V to +10V with U.sub.DS=3 V.

[0710] FIG. 14b shows the output characteristics of the semiconductor obtained by drop casting of compound A1) from a DMP:Toluene (1:3) solution (example 63) with U.sub.DS=0 V to +8 V with U.sub.GS=2, 4, 6, 8 and 10V.

EXAMPLES

Sample Preparation 1 (Mainly Used for the Characterization of the Various Semiconductors):

[0711] Degenerately doped silicon wafers (wafers from WRS Materials heavily p-doped with boron, 550-600 μm thickness) coated with a 240 nm thermally grown silicon dioxide were used as substrate. They were subjected to 2 min oxygen plasma treatment (100 W, 20 standard cubic centimeters per minute (sccm) gas flow) and subsequently immersed into a 0.2 vol % solution of octadecyltrichlorosilane (OTS) in toluene for 17 minutes at room temperature. Subsequently the sample was removed from the solution, rinsed with toluene and baked for 30 min at 90° C. Subsequently a 0.5-1 mm thick layer of polydimethylsiloxane (PDMS) comprising holes with a diameter of 7.3 mm was placed onto the hydrophobic substrate that was subsequently subjected to a 5 minutes treatment with air plasma. This plasma burns away the hydrophobic monolayer in the locations of the holes of the PDMS layer exposing the bare, more hydrophilic SiO.sub.2 surface.

[0712] The respective solvents were either used pure or a mixture of the respective solvents was prepared initially. 0.1 wt % of semiconductor powder was dissolved in the respective solvent or solvent mixture and filtered through a 0.2 μm polytetrafluoroethylene (PTFE) filter. The substrate was placed on a hotplate (temperature for all solvents 70° C. except toluene, here 30° C. was used for drying) and 1 μL of the organic semiconductor solution was drop casted with a pipette onto the hydrophilic areas. Substrates were removed once the solution had dried. Optical images were recorded under a polarized microscope in reflection mode.

Sample Preparation 2 (Used to Make the Experiments with the Solvent Mixture and to Fabricate Transistors):

[0713] Degenerately doped silicon wafers coated with Al.sub.2O.sub.3(30 nm thick, grown via atomic layer deposition) were subjected to a 2 minutes treatment with oxygen plasma (100 W, 20 sccm gas flow) and subsequently immersed into a 1.5 mM solution of tetradecyl phosphonic acid (TDPA) in isopropanol for 1 hour at room temperature. Subsequently the sample was removed from the solution and baked for 5 min at 120° C. This procedure yields a hydrophobic self-assembled monolayer (SAM) on the Al.sub.2O.sub.3 surface with a surface energy of 22 mN/m (surface energy determined via contact angle measurement). Subsequently a layer of PDMS having a thickness of 0.5-1 mm and comprising holes with a diameter of 7.3 mm was placed onto the hydrophobic substrate that was subsequently subjected to a 5 minutes treatment with air plasma. This plasma burns away the hydrophobic monolayer in the locations of the holes of the PDMS layer exposing the bare, more hydrophilic Al.sub.2O.sub.3 surface. The resulting plasma-treated hydrophilic areas of the substrate were then treated with 4-ethoxyphenylphosphonic acid (EPPA) in the same manner as described above for the TDPA SAM. This process yields a hydrophilic EPPA SAM in the circular regions that had been subjected to the second plasma treatment step. The surface energy of the EPPA-treated areas was determined to be 36 mN/m.

[0714] 0.1 wt % of semiconductor powder was dissolved in the respective solvent for 1 h at 80° C. under constant shaking. After cooling the solution to room temperature it was filtered through a 0.2 μm PTFE filter. In the case that solvent mixtures were used, first the semiconductor was dissolved in the respective individual solvent, subjected to shaking at 80° C. for 1 h, filtered and subsequently mixed to the respective solvent ratios. 1 μL of the organic semiconductor solution was drop casted with a pipette onto the hydrophilic EPPA areas at an elevated substrate temperature (70° C., substrate placed on hotplate). After several hours to 2 days of drying at 70° C. the samples were transferred to a vacuum oven and heated to 60° C. to 90° C. for additional 3 hours to completely remove residual solvent. Optical images were recorded under a polarized microscope in reflection mode.

Sample Preparation Method 3:

[0715] A given amount of polystyrene (PS), molecular weight 2.000.000 (obtained from Alfa Aesar; PS-Lot: K05Y052) was dissolved in the respective solvents at room temperature and stirred until all polymer was dissolved. Then 0.1 wt % of the organic semiconductor was dissolved in the mixture. Microscopy cover glass-slides were used as substrates and were thoroughly rinsed with acetone first. The solution was then dropcast onto a microscopy cover glass slide that had been heated to 70° C. on a hotplate. In an alternative experiment the solution was applied via a wire-bar coater (4 μm) onto a heated (70° C.) glass slide. Microscopy images were obtained with an optical microscope.

Transistor Fabrication and Electrical Measurement:

[0716] Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a Lakeshore CRX—6.5K probe station in vacuum (<10.sup.−6 mbar) using an Agilent 4145C Semiconductor Parameter Analyzer.

Viscosity Measurement of the Solvents, Solvent Mixtures or Polymer-Solvent Mixtures:

[0717] The viscosities were measured using a Brookfield DV-II+Pro Viscosimeter at 23° C. temperature at a shear rate of 93 s-1 at a rotational speed of 100 rpm using a 13R cup and a 21 Spindle.

Process Description of Surface Tension Measurement of the Solvents and Solvent Mixtures:

[0718] The surface tension was measured on a Tensiometer K100 from Kriss using the Wilhelmy-plate method.

Example 1

[0719] According to the afore-mentioned sample preparation method 2 a crystalline material of semiconductor (A1) was prepared using a solvent mixture of DMP and toluene (wt. ratio 1:3). The solids content of the semiconductor solution was 0.1 wt. % and drying was performed at 70° C. on a hotplate. FIG. 1 shows the polarized optical micrograph of the obtained crystalline organic film. The combination of DMP as a solvent (L1) in the sense of the invention with toluene as a solvent (L2) leads to a semiconductor material having a large area of thin connected continuous crystals.

Example 2 (Comparative)

[0720] According to the afore-mentioned sample preparation method 2 a crystalline material of semiconductor (A1) was prepared using acetylacetone as solvent. The solids content of the semiconductor solution was 0.1 wt.-% and drying was performed at 70° C. on a hotplate. FIG. 2 shows the polarized optical micrograph of the obtained crystalline organic film. The use of a solvent that is not a solvent (L1) in the sense of the invention leads to a semiconductor material having thick disconnected polycrystalline agglomerates.

Example 3 (Comparative)

[0721] According to the afore-mentioned sample preparation method 2 a crystalline material of semiconductor (A1) was prepared using toluene as solvent. The solids content of the semiconductor solution was 0.1 wt.-% and drying was performed at 30° C. on a hotplate. FIG. 3 shows the polarized optical micrograph of the obtained crystalline organic film. The use of toluene alone, being a solvent that is not a solvent (L1) in the sense of the invention, leads to a semiconductor material having thick disconnected polycrystalline agglomerates.

Examples 4 to 22

[0722] According to the afore-mentioned sample preparation method 2 a crystalline material of semiconductor (A1) was prepared using a pure solvent according to table 1 as solvent. The solids content of the semiconductor solution was 0.1 wt. % and drying was performed at 70° C. (except toluene, where 30° C. was used for drying) on a hotplate. The obtained crystalline semiconductor materials were examined by polarized optical microscopy. The results are shown in table 1. With the solvents (L1) in the sense of the invention in each case semiconductor materials having a large area of thin connected crystals were obtained. The use of solvents different from the solvents (L1) leads to semiconductor materials having thick polycrystalline agglomerates.

TABLE-US-00003 TABLE 1 List of pure solvents tested: surface boiling viscosity tension polarized point [mPa s] [mN/m] @ optical example no. solvent [° C.] @20° C. 20° C. microscopy.sup.#) 4 Dimethyl Phthalate 283 14.4 41.9 (+) (DMP) 5 Di-ethyl Phthalate 295 10.6 37.5 (+) (DEP) 6 Di-allyl Phthalate 165 8.5 39.0 (+) (DAP) 7 DMSO 189 4.0 43.5 (+) 8 Ethyl Benzoate 211 2.2 34.6 (+) 9 Ethyl Salicylate 222 1.8 39.1 (+) 10 Acetophenone 202 1.7 39.0 (+) 11 Propylene Carbonate 242 1.7 41.1 (+) 12 NMP 202 1.7 40.8 (+) 13 THN 207 1.4 32.6 (+) 14 1,2-DCB 180 1.3 36.6 (+) 15 Amyl Acetate 149 0.9 25.1 (−) 16 Acetyl Acetone (Acac) 140 0.8 31.2 (−) 17 Chlorobenzene 131 0.8 33.6 (−) 18 Butyl Acetate 126 0.7 25.1 (−) 19 Nitroethane 112 0.6 32.0 (−) 20 Toluene 111 0.6 28.6 (−) 21 Trichloromethane 61 0.5 27.5 (−) 22 Ethyl Acetate (Ethac) 77 0.4 23.2 (−) .sup.#)(+) = a thin crystalline film is formed, (−) = thick disconnected polycrystalline agglomerates are formed

[0723] The solvent parameters of the pure solvents were taken from Knovel Critical Tables (2nd Edition 2008), electronic ISBN: 978-1-59124-550-6.

Examples 23 to 40

[0724] According to the afore-mentioned sample preparation method 2 for solvent mixtures and sample preparation method 3 for solvent-polymer mixtures a crystalline material of semiconductor (A1) was prepared using a solvent mixture or solvent-polymer mixture according to table 2. All solutions were deposited by drop casting unless noted otherwise. The solids content of the semiconductor solution was 0.1 wt.-% and drying was performed at 70° C. (except for pure toluene that was dried at 30° C. on a hotplate. The obtained crystalline semiconductor materials were examined by polarized optical microscopy. The results are shown in table 2. With solvent mixtures containing a solvent (L1) in the sense of the invention in each case semiconductor materials having a large area of thin connected crystals were obtained. If toluene is used as solvent, an increase in the viscosity of the solution by using polystyrene (PS) as thickener does not lead to an improvement in the quality of the obtained semiconductor material. The use of toluene-polymer mixtures leads to semiconductor materials having thick disconnected crystals. In other words it is not enough to artificially increase the viscosity of a low viscous solvents such as toluene by adding a thickener in order to obtain a preferable crystallization of the semiconductor as in the case that solvents according to the present invention are contained in a solution.

TABLE-US-00004 TABLE 2 List of solvent mixtures and solvent-polymer mixtures tested solvent mixture, Surface polymer-solvent Viscosity tension crystal example no. mixture [mPas] [mN/m] form 23 DMP 14.4 41.9  thin 24 Toluene 0.6 28.6  thick 25 Toluene: PS 3.5 not thick (6.6 mg PS/1 g measured toluene) 26 Toluene: PS 5.3 not thick (9.8 mg PS/1 g measured toluene) 27 Toluene: PS 8 not thick (13.2 mg PS/1 g measured toluene) 28 DMP: PS 20 not thin (1.5 mg PS/1 g measured DMP) 29 DEP: PS 19 not thin (2.3 mg PS/1 g measured DEP) 30 DMP: PS (wire-bar 20 not thin coated) measured (1.5 mg PS/1 g DMP) 31 DEP: PS (wire-bar 19 not thin coated) measured (2.3 mg PS/1 g DEP) 32 DMP:Toluene (1:3) 0.75 not thin measured 33 DMP:Toluene (1:9) 0.5 27.29 thin 34 DMP:Acetylacetone 1 32.67 thin (1:3) 35 DMP:Acetylacetone 0.5 29.65 thin (1:9) 36 DMP:Nitroethane Not Not thin (1:3) measured measured 37 DMP:1,2-DCB (1:3) Not Not thin measured measured 38 DMP:Amylacetate Not Not thin (1:3) measured measured 39 DAP:Acetylacetone Not Not thin (1:3) measured measured 40 DAP:Acetylacetone Not Not thin (1:3) measured measured

Examples 41 to 47

[0725] According to the afore-mentioned sample preparation method 1 a crystalline material of semiconductors according to table 3 was prepared using a solvent mixture or solvent-polymer mixture according to table 3. All solutions were deposited by drop casting unless noted otherwise. The solids content of the semiconductor solution was 0.1 wt. % and drying was performed at 70° C. (except toluene, where 30° C. was used for drying) on a hotplate. The obtained crystalline semiconductor materials were examined by polarized optical microscopy. The results are shown in table 3.

TABLE-US-00005 TABLE 3 List of semiconductors tested (sample preparation method 1): solvent DMP DMP:Toluene(1:3) Acetophenone Toluene thin thin thin thin example no. semiconductor layers layers layers layers 41 A4 yes not measured yes no 42 A1 Yes Yes Yes no 43 A3 yes yes yes no 44 A5 yes yes yes no 45 A6 yes yes yes no 46 A7 yes yes yes no 47 A8 yes yes yes not measured

Example 48: Drop-Casting of Semiconductor A9)

[0726] A 0.1 wt. % solution of A9) in a solvent according to table 1 is applied to a SiO.sub.2 substrate and the solvent allowed to evaporate. For the preparation of the solutions of A9) in the phthalates the semiconductor is stirred in the phthalate at 80° C. for 60 minutes. FIG. 4a shows the polarized optical micrograph of the crystalline organic film obtained by drop-casting of compound A9) from DMP and FIG. 4b shows the micrograph of film obtained by drop-casting of compound A9) from EthAc. As can be seen, the crystals obtained from the compositions of the invention show remarkably larger crystalline areas.

TABLE-US-00006 TABLE 4 example solvent crystal length [μm] crystal width [μm] 48.1 DMP  50 5 48.2 DEP 100 30 48.3 DAP 100 20 C48.4.sup.+) ethylacetate  .sup. 3.sup.# 0.5.sup.# .sup.+)comparative, .sup.#small polycrystalline to amorphous disconnected agglomerates

Example 49: Drop-Casting of Semiconductor A10)

[0727] A 0.1 wt. % solution of A10) in a solvent according to table 1 is applied to a SiO.sub.2 substrate and the solvent allowed to evaporate. For the preparation of the solutions of A10) in the phthalates the semiconductor is stirred in the phthalate at 80° C. for 60 minutes. In the polarized optical micrograph the crystals obtained from the compositions of the invention show remarkably larger crystalline areas.

TABLE-US-00007 TABLE 5 example solvent crystal length [μm] crystal width [μm] 49.1 DMP 35  5 49.2 DEP 100  50 49.3 DAP 60 50 C49.4.sup.+) ethylacetate .sup. 20.sup.# .sup. 10.sup.# .sup.+)comparative, .sup.#small polycrystalline to amorphous disconnected agglomerates

Example 50: Drop-Casting of Semiconductor A3)

[0728] A 0.1 wt. % solution of A3) in a solvent according to table 1 is applied to a SiO.sub.2 substrate and the solvent allowed to evaporate. For the preparation of the solutions of A3) in the phthalates the semiconductor is stirred in the phthalate at 80° C. for 60 minutes. In the polarized optical micrograph the crystals obtained from the compositions of the invention show remarkably larger crystalline areas.

TABLE-US-00008 TABLE 6 example solvent crystal length [μm] crystal width [μm] 50.1 DAP 200  250  C50.2.sup.+) ethylacetate 20 3 C50.3.sup.+) acetylacetone .sup. 20.sup.# .sup. 3.sup.# .sup.+)comparative, .sup.#small polycrystalline to amorphous disconnected agglomerates

Example 51: Drop-Casting of Semiconductor A1)

[0729] A 0.1 wt. % solution of A1) in a solvent according to table 1 is applied to a SiO.sub.2 substrate and the solvent allowed to evaporate. For the preparation of the solutions of A1) in the phthalates the semiconductor is stirred in the phthalate at 80° C. for 60 minutes. In the polarized optical micrograph the crystals obtained from the compositions of the invention show remarkably larger crystalline areas.

TABLE-US-00009 TABLE 7 example solvent crystal length [μm] crystal width [μm] 51.1 DMP 500 200 51.2 DEP 1200  650 51.3 DAP 250 150 C51.3.sup.+) ethylacetate  .sup. 3.sup.#  .sup. 2.sup.# .sup.+)comparative, .sup.#small polycrystalline to amorphous disconnected agglomerates

Preparation and Electrical Characterization of OFET Devices

Example 52: Drop-Casting of A1) from DMP Solution on a SiO.SUB.2 .Wafer

[0730] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 100 nm insulating dielectric layer of thermally oxidized silicon) were used as back gate substrate. 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0731] The measurement results are depicted in FIGS. 5a and 5b, respectively.

Example 53: Drop-Casting of A1) from DMP:Acac (1:9) Solution on a SiO.SUB.2 .Wafer

[0732] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in a 1:9 mixture of dimethyl phthalate and acetylacetone for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 100 nm insulating dielectric layer of thermally oxidized silicon) were used as back gate substrate. 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0733] The measurement results are depicted in FIGS. 6a and 6b, respectively.

Example 54: Drop-Casting of A1) from a DMP Solution on an Al.SUB.2.O.SUB.3 .Layer

[0734] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 30 nm insulating dielectric layer of Al.sub.2O.sub.3) were used as back gate substrate. 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0735] The measurement results are depicted in FIGS. 7a and 7b, respectively.

Example 55: Drop-Casting of A1) from a DM P Solution on Al.SUB.2.O.SUB.3 .after Surface Modification

[0736] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 30 nm insulating dielectric layer of Al.sub.2O.sub.3) were used as back gate substrate.

[0737] Prior to material deposition, a surface treatment was conducted; the substrate was exposed to O.sub.2 plasma for 300 seconds. 4-Ethoxyphenylphosphonic acid (CAS 69387-02-6) was dissolved in isopropanol at a concentration of 2 mMol (typically 4 mg/10 ml) and stirred at room temperature for 20 minutes. The substrate was immersed in the solution for 1 hour in a covered petri dish. After subsequent rinsing with isopropanol and drying under N.sub.2, the substrates were baked at 150° C. on a hotplate. 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0738] The measurement results are depicted in FIGS. 8a and 8b, respectively.

Example 56: Drop-Casting of A1) from a DMP Solution on a PET Substrate, Production of a Bottom-Contact Top-Gate Field Effect Transistor Using a PVCH/PMMA Top Gate

[0739] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. A polyethylene terephthalate (PET) foil (Hostaphan 4600GN 175 from Mitsubishi Polyester Film) was used as substrate. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 500 μm and channel length (L) of 50 μm. 1 to 10 μL of solution was deposited onto the substrate on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of the solvent the sample was put in a vacuum oven at 70° C. for 1 h to eliminate residual solvent. Polyvinylcyclohexane (PVCH) (0.4 wt % in cyclohexane) was spin-coated (4000 RPM, 30 seconds) and dried for 5 minutes at 90° C. Polymethylmethacrylate (PMMA) (4 to 7 wt.-% in butylacetate/ethyl-lactate [4:6]) was spin-coated (2000 RPM/60 seconds) and dried for 120 seconds at 90° C. The PVCH/PMMA dielectric thickness was 420 nm (∈ r=4). Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0740] The measurement results are depicted in FIGS. 9a and 9b, respectively.

Example 57: Inkjet Printing of A1) from DMP Solution on a SiO.SUB.2 .Wafer

[0741] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 100 nm insulating dielectric layer of thermally oxidized silicon) were used as back gate substrate. The ink was printed with a Dimatix DMP2831 printer at a drop space of 20 μm with the nozzle at 35° C. and the printing plate at room temperature. The printed substrates were dried 5 h at 60° C. in ambient air followed by a second drying step for one hour at 110° C. in a vacuum oven (about 5 mbar pressure). After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0742] The measurement results are depicted in FIGS. 10a and 10b, respectively.

Example 58: Inkjet Printing of A1) from a DMP Solution on Al.SUB.2.O.SUB.3 .after Surface Modification

[0743] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 30 nm insulating dielectric layer of Al.sub.2O.sub.3) were used as back gate substrate. Prior to material deposition, a surface treatment was conducted; the substrate was exposed to O.sub.2 plasma for 300 seconds. 4-Ethoxyphenylphosphonic acid, (CAS 69387-02-6) was dissolved in isopropanol at a concentration of 2 mMol (typically 4 mg/10 ml) and stirred at room temperature for 20 minutes. The substrate was immersed in the solution for 1 hour in a covered petri dish. After subsequent rinsing with isopropanol and drying under N2, the substrates were baked at 150° C. on a hotplate. The ink was printed with a Dimatix DMP2831 printer at a drop space of 20 μm with the nozzle at 35° C. and the printing plate at room temperature. The printed substrates were dried 5 h at 60° C. in ambient air followed by a second drying step for one hour at 110° C. in a vacuum oven (about 5 mbar pressure). After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6E-6 mbar through a kapton shadow mask via thermal evaporation yielding a typical channel W/L of 200 μm/100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0744] The measurement results are depicted in FIGS. 11a and 11b, respectively.

Example 59: Drop-Casting of A1) from a DMP Solution on a SiO.SUB.2 .Wafer Using a Poly(Methyl Methacrylate)/Trimethylolpropane Triacrylate Bottom-Gate Dielectric

[0745] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 100 nm insulating dielectric layer of thermally oxidized silicon) with a UV-crosslinked polymer dielectric were used as backgate substrate. The dielectric properties are summarized in the table below.

TABLE-US-00010 spin-coating film UV polymer RPM(time) drying crosslinking ε.sub.r thickness TMPTA/ 2000/10000 10 min 10 × 10 LEDs 3.5 328 nm PMMA (60 seconds) 90° C. UV meter 53″ 23 mW/cm.sup.2 ε.sub.r = relative permittivity (dielectric constant)

[0746] 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 60 to 90° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a typical channel W/L of 200 μm/100 μm. Electrical characterization was conducted in a dark box under ambient conditions. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0747] The measurement results are depicted in FIGS. 12a and 12b, respectively.

Example 60: Inkjet Printing of A3) from DMP Solution on Al.SUB.2.O.SUB.3

[0748] A 0.1 wt.-% solution of the semiconductor material A3) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Si/SiO.sub.2 wafers from WRS Materials heavily p-doped with boron (550 to 600 μm thickness, 30 nm insulating dielectric layer of Al.sub.2O.sub.3) were used as back gate substrate. The ink was printed with a Dimatix DMP2831 printer at a drop space of 20 μm with the nozzle at 35° C. and the printing plate at room temperature. The printed substrates were dried 5 h at 60° C. in ambient air followed by a second drying step for one hour at 110° C. in a vacuum oven (about 5 mbar pressure). After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 70° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 μm and channel length (L) of 100 μm. Electrical characterization was conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0749] The measurement results are depicted in FIGS. 13a and 13b, respectively.

Examples 61 and 62: (Impact of the Drying Time of the Droplets on the Crystal Form)

Example 61

[0750] According to the procedure listed under sample preparation 1 a mixture of semiconductor (A1) with a mixture of DM P/Acac (1:3) was prepared, applied by drop-casting onto a glass microscopy cover slide and dried at 70° C. substrate temperature. During drying the cyrstalization was observed in-situ in transmission polarized microscopy setup. Immediately after the liquid was placed on the cover slide the crystallization started in the form of thin crystals that floated on the DMP/Acac mixture.

Comparative Example 62

[0751] 0.1 weight percent of semiconductor (A1) was dissolved in toluene and a 10 μm droplet applied by drop-casting on a silicon dioxide coated silicon wafer held at room temperature. Subsequently a petri dish was placed over the silicon wafer thus also enclosing the droplet. The drying time therefore was significantly prolonged (>30 min). After drying of the liquid disconnected large crystals comparable to those shown in FIG. 3 were observed.

[0752] Example 61 and comparative example 62 show that the drying time of the solution does not have an impact on the crystal habit. With a solvent (L1) according to the invention a good semiconductor material is obtained even if the drying time is significantly shorter than in a comparison with a solvent that is not a solvent (L1) according to the invention.

Example 63: (Drop-Casting of A1) from a DMP:Toluene (1:3) Mixture on Al.SUB.2.O.SUB.3 .after Surface Modification)

[0753] A 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in dimethyl phthalate for 1 h at 80° C. and then stirred for further 30 minutes. A second 0.1 wt.-% solution of the semiconductor material A1) was prepared by dissolution in toluene for 1 h at 80° C. and then stirred for further 30 minutes. The two solutions were mixed at a ratio of 1 (DMP) to 3 (toluene). The solution was allowed to cool to ambient temperature and was filtered through a 0.2 μm PTFE filter. Silicon wafers from WRS Materials (heavily p-doped with boron, 550 to 600 μm thickness) coated with Al.sub.2O.sub.3 (30 nm thick, grown via atomic layer deposition) were subjected to a 2 minutes treatment with oxygen plasma (100 W, 20 sccm gas flow) and subsequently immersed into a 1.5 mM solution of tetradecyl phosphonic acid (TDPA) in isopropanol for 1 hour at room temperature. Subsequently the sample was removed from the solution, rinsed with isopropanol and baked for 5 min at 120° C. on a hotplate. This procedure yields a hydrophobic self-assembled monolayer (SAM) on the Al.sub.2O.sub.3 surface with a surface energy of 22 mN/m (surface energy determined via water contact angle measurement). Subsequently a layer of PDMS having a thickness of 0.5-1 mm and comprising holes with a diameter of 7.3 mm was placed onto the hydrophobic substrate that was subsequently subjected to a 2 minutes treatment with air plasma (100 W, 20 sccm gas flow). This plasma burns away the hydrophobic monolayer in the locations of the holes of the PDMS layer exposing the bare, more hydrophilic Al.sub.2O.sub.3 surface. 1 to 10 μL of solution was deposited onto the wafer on a hotplate at 70° C. in a flow box. After complete evaporation of solvent the sample was put in a vacuum oven for 1 h at 90° C. to eliminate residual solvent trapped in the film. Gold contacts (Umicore, 99.99%) were deposited at a base pressure of 6×10.sup.−6 mbar through a kapton shadow mask via thermal evaporation yielding a channel width (W) of 200 m and channel length (L) of 50 m. The degenerately doped silicon wafers were used as back gate substrate for electrical characterization, conducted in a dark box under ambient conditions using an Agilent 4145C Semiconductor Parameter Analyzer.

[0754] The measurement results are depicted in FIGS. 14a and 14b, respectively.