ORGANIC SEMICONDUCTOR COMPOSITION

Abstract

Organic semiconductor composition, comprising an organic semiconductor (OSC) material and a binder which is a spirobifluorene compound comprising 1 to 4 substituted or unsubstituted spirobifluorene moieties of formula 26.

##STR00001##

Claims

1. An organic semiconductor composition, comprising an organic semiconductor (OSC) material a) and a binder b) which is a spirobifluorene compound comprising 1 to 4 substituted or unsubstituted spirobifluorene moieties of formula (26) ##STR00036##

2. The organic semiconductor composition in accordance with claim 1 wherein the spirobifluorene compound has a molecular weight of 1500 Daltons or less.

3. The organic semiconductor composition in accordance with claim 1, additionally comprising one or more organic solvents.

4. The organic semiconductor composition in accordance with claim 1 wherein the binder b) has a glass transition temperature of at least 120° C.

5. The organic semiconductor composition in accordance with claim 1 wherein the spirobifluorene compound is a 3-substituted 9,9′-spirobifluorene compound.

6. The organic semiconductor composition in accordance with claim 1 wherein the organic semiconductor material has a field effect mobility of at least 0.001 cm2/Vs.

7. The organic semiconductor composition in accordance with claim 1 wherein the organic semiconductor is a small molecule with a molecular weight of 1500 Da or less.

8. The organic semiconductor composition in accordance with claim 1 wherein the SBF compound has a HOMO level of −5.1 eV or less.

9. The organic semiconductor composition in accordance with claim 1 wherein the weight ratio of organic semiconductor to binder is from 1:99 to 99:1.

10. The organic semiconductor composition in accordance with claim 1 wherein the organic semiconductor material is selected from compounds of formulae ##STR00037## wherein Ar1 to Ar7 are the same or different at each occurrence and are each independently selected from the group consisting of monocyclic aromatic rings and monocyclic heteroaryl aromatic rings, with at least one of Ar1 to Ar7 being substituted with at least one substituent X which may be the same or different at each occurrence and is selected from the group consisting of unsubstituted or substituted straight, branched or cyclic alkyl groups having from 1 to 50 carbon atoms, alkoxy groups having from 1 to 50 carbon atoms, aryloxy groups having from 6 to 40 carbon atoms, alkylaryloxy groups having from 7 to 40 carbon atoms, alkoxycarbonyl groups having from 2 to 40 carbon atoms, aryloxycarbonyl groups having from 7 to 40 carbon atoms, amino groups that may be unsubstituted or substituted with one or two alkyl groups having from 1 to 20 carbon atoms, each of which may be the same or different, amido groups, silyl groups that may be unsubstituted or substituted with one, two or three alkyl groups having from 1 to 20 carbon atoms, silylethinyl groups that may be unsubstituted or substituted with one, two or three alkyl groups having from 1 to 20 carbon atoms, alkenyl groups having from 2 to 20 carbon atoms, the carbamoyl group, the haloformyl group, the formyl group, the cyano group, the isocyano group, the isocyanate group, the thiocyanate group, the thioisocyanate group, OH, nitro, cyano, haloalkyl groups having 1 to 20 carbon atoms and wherein Ar1, Ar2 and Ar3 may each optionally be fused to one or more further monocyclic aromatic or heteroaromatic rings.

11. The organic semiconductor composition in accordance with claim 10 wherein at least one of Ar1 to Ar7 comprises a 5 to 7 membered heteroaryl group containing from 1 to 3 sulfur atoms, oxygen atoms, selenium atoms and/or nitrogen atoms.

12. An electronic component or device comprising a gate electrode, a source electrode and a drain electrode, said component further comprising an organic semiconducting material between the source and the drain electrode, which organic semiconducting material is obtained using an organic semiconductor composition in accordance with claim 1.

13. A process for the manufacture of an electronic component or device, the process comprising the following steps: a) providing an organic semiconductor composition in accordance with claim 1, optionally with a solvent or solvent mixture, b) applying the organic semiconductor composition obtained in step a) to a substrate; c) optionally evaporating the solvent or the solvent mixture to form a solid layer comprising the organic semiconducting material, d) optionally removing the solid layer obtained in step c) or the substrate from the solid layer.

14. An organic electronic device comprising the organic semiconductor composition in accordance with claim 1.

15. The organic electronic device in accordance with claim 14 wherein the organic electronic device is an organic field effect transistor.

Description

EXAMPLES

[0157] Organic Thin Film Transistors (OTFTs) were fabricated in top gate and bottom contact configuration using glass based substrates as follows:

[0158] 1″ square glass substrates (ex: Corning XG) were cleaned using sonication bathes for 5 minutes in Deconex (3% in water) followed by rinsing in ultrapure water and dried using compressed air. A planarization layer was first spincoated on top of the cleaned substrates in order to create a 30 nm film after photo-crosslinking. Au (30 nm) bottom contact source/drain (S/D) electrodes were deposited on top of the buffer layer by thermal evaporation through a shadow mask. The 16 transistors S/D consisted of electrodes with channel length of 50 μm and channel width of 0.5 mm. The substrates then underwent UV/O.sub.3 treatment (model 42-220, from Jelight Company, Inc.), treatment time 5 min. Prior to spin coating of the OSC solution, a 10 mM solution of 4-fluorobenzenethiol in 2-propanol was applied to the surface of the electrodes for 1 minute followed by spin coating and rinsing by fresh 2-propanol, followed by drying on a hotplate at 100° C. The organic semiconductor (OSC) formulation was spin coated onto the SD electrodes using a Laurell spinner set at 1500 rpm followed by baking on a hotplate for 60 seconds at 100° C. A solution of Hyflon® AD SF (9.2% w/w) was spin coated at 3000 rpm and the samples were baked on a hotplate for 60 s at 100° C. Gate electrodes were defined by evaporation of Aluminum through a shadow mask in a thermal evaporator system.

[0159] OTFT Characterization

[0160] OTFTs were tested using a Cascade Microtech EP6 DC probe station in conjunction with an Agilent B1500A semiconductor parameter analyzer. The Agilent system calculated the linear mobility according to the equation shown below (Equation 2).

[00001]${\mathrm{.Math.}}_{\mathrm{Lin}}=\frac{\partial I_{\mathrm{DS}}}{\partial V_G}.Math.\frac{L}{{\mathrm{WC}}_i.Math.V_{\mathrm{DS}}}$

[0161] where L is the transistor length, W is the transistor width and Ci is the dielectric capacitance per unit area. Vds was set at −4V unless otherwise stated. The mobility values reported are an average of the 5 highest points in accumulation for each transistor. The standard deviation of the mobility values is reported as a percentage of the mean.

COMPARATIVE EXAMPLES (i) to (iv)

[0162] The OTFT arrays fabricated and characterized as the Comparative Examples (i) to (v) were fabricated and tested as described above. The formulations tested in the comparative examples included small molecule semiconductor however these formulations did not incorporate any binders.

Comparative Example (i)

1,4,8,11-tetramethyl-6,13-Triethylsilylethynylpentacene Without Binder; TG OTFT

[0163] 1,4,8,11-tetramethyl-6,13-triethylsilylethynylpentacene from the series of compounds (14) represented by Formula (19) was formulated in tetralin at 2% by weight total solids content. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0164] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00001 μ Lin 1.8 ± 0.8 cm.sup.2/Vs

Comparative Example (ii)

2,8-Difluoro-5,11-bis(Triethylsilylethynyl) anthradithiophene Without Binder, TG OTFT

[0165] 2,8-Difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene from the series of compounds (15) represented by Formula (20) was formulated in tetralin at 2% by weight total solids content. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0166] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00002 μ Lin 0.3 ± 0.1 cm.sup.2/Vs

Comparative Example (iii)

2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene Without Binder, TG OTFT

[0167] 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene from the series of compounds (16) represented by Formula (21) was formulated in tetralin at 2% by weight total solids content. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0168] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00003 μ Lin 0.3 ± 0.2 cm.sup.2/Vs

Comparative Example (iv)

1,1′-di(decan-5-yl)-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione Without Binder, TG OTFT

[0169] 1,1′-di(decan-5-yl-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione from the series of compounds (24) represented by Formula (25) was formulated in tetralin at 2% by weight total solids content. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0170] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00004 μ Lin 0.1 ± 0.08 cm.sup.2/Vs

COMPARATIVE EXAMPLES (v) to (viii)

[0171] The OTFT arrays fabricated and characterized as the Comparative Examples (v) to (ix) were fabricated and tested as described above. The formulations tested in the comparative examples (v) to (ix) included a small molecule semiconductor and a polymer as binder.

Comparative Example (v)

1,4,8,11-tetramethyl-6,13-Triethylsilylethynylpentacene With Polymer Binder; TG OTFT

[0172] 1,4,8,11-tetramethyl-6,13-triethylsilylethynylpentacene from the series of compounds (14) represented by Formula (19) and Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] were formulated in tetralin in a ratio 1:1 at total solids content of 2% by weight. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0173] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00005 μ Lin 3.8 ± 1.1 cm.sup.2/Vs

Comparative Example (vi)

2,8-Difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene With Polymer Binder, TG OTFT

[0174] 2,8-Difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene from the series of compounds (15) represented by Formula (20) and Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] were formulated in tetralin in a ratio 1:1 at total solids content of 2% by weight. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0175] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00006 μ Lin 2.2 ± 0.8 cm.sup.2/Vs

Comparative Example (vii)

2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene With Polymer Binder, TG OTFT

[0176] 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene from the series of compounds (16) represented by Formula (21) and Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] were formulated in tetralin in a ratio 1:1 at total solids content of 2% by weight. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0177] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00007 μ Lin 0.1 ± 0.06 cm.sup.2/Vs

Comparative Example (viii)

1,1′-di(decan-5-yl)-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione With Polymer Binder, TG OTFT

[0178] 1,1′-di(decan-5-yl)-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione from the series of compounds (24) represented by Formula (25) and Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] were formulated in tetralin in a ratio 1:1 at total solids content of 2% by weight. This was coated as an OSC layer in an OTFT device according to the method shown above for glass substrate.

[0179] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00008 μ Lin 0.1 ± 0.08 cm.sup.2/Vs

EXAMPLES 1 to 4

[0180] The OTFT arrays fabricated and characterized as the Examples (1) to (5) were fabricated and tested as described above. The formulations tested in the examples (1) to (5) included small molecule semiconductor and an amorphous small-molecule as binder. In these examples the ratio of binder to the semiconductor is in parts by weight.

Example (1)

1,4,8,11-tetramethyl-6,13-Triethylsilylethynylpentacene With Small-Molecule Binder; TG OTFT

[0181] Binder 3-(9,9′-spirobi[fluorene]-3-yl)-3′-(9,9′-spirobi[fluorene]-6-yl)biphenyl was formulated with 1,4,8,11-tetramethyl-6,13-triethylsilylethynyl pentacene from the series of compounds (14) represented by Formula (19) in a ratio 1:1 at a total solids content of 2% by weight in tetralin and coated as an OSC layer in an OTFT device according to the method shown above for glass substrate devices.

[0182] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00009 μ Lin 3.8 ± 0.3 cm.sup.2/Vs

Example (2)

2,8-Difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene With Small-Molecule Binder; TG OTFT

[0183] Binder 3-(9,9′-spirobi[fluorene]-3-yl)-3′-(9,9′-spirobi[fluorene]-6-yl)biphenyl was formulated with 2,8-Difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene from the series of compounds (15) represented by Formula (20) in a ratio 1:1 at a total solids content of 2% by weight in tetralin and coated as an OSC layer in an OTFT device according to the method shown above for glass substrate devices.

[0184] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00010 μ Lin 3.3 ± 0.5 cm.sup.2/Vs

Example (3)

2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene With Small-Molecule Binder; TG OTFT

[0185] Binder 3-(9,9′-spirobi[fluorene]-3-yl)-3′-(9,9′-spirobi[fluorene]-6-yl)biphenyl was formulated with 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene from the series of compounds (16) represented by Formula (21) in a ratio 1:1 at a total solids content of 2% by weight in tetralin and coated as an OSC layer in an OTFT device according to the method shown above for glass substrate devices.

[0186] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00011 μ Lin 0.4 ± 0.07 cm.sup.2/Vs

Example (4)

1,1′-di(decan-5-yl)-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione With Small-Molecule Binder; TG OTFT

[0187] Binder 3-(9,9′-spirobi[fluorene]-3-yl)-3′-(9,9′-spirobi[fluorene]-6-yl)biphenyl was formulated with 1,1′-di(decan-5-yl)-7,7′-difluoro-1H,1′H-3,3′-bipyrrolo[2,3-b]quinoxaline-2,2′(4H,4′H)-dione from the series of compounds (24) represented by Formula (25) in a ratio 1:1 at a total solids content of 2% by weight in tetralin and coated as an OSC layer in an OTFT device according to the method shown above for glass substrate devices.

[0188] The TFT performance of this formulation is shown in Table (i) below:

TABLE-US-00012 μ Lin 0.13 ± 0.005 cm.sup.2/Vs

[0189] The previous examples show that the organic semiconductor compositions in accordance with the present invention, comprising an organic semiconductor and a monomeric binder on the basis of substituted or unsubstituted spirobifluorene yield OTFTs with improved performance compared to OTFTs obtained using compositions in accordance with the prior art.