Patterning method for preparing top-gate, bottom-contact organic field effect transistors

Abstract

The present invention relates to a process for the preparation of a top-gate, bottom-contact organic field effect transistor on a substrate, which organic field effect transistor comprises source and drain electrodes, a semiconducting layer, a cured first dielectric layer and a gate electrode, and which process comprises the steps of: i) applying a composition comprising an organic semiconducting material to form the semiconducting layer, ii) applying a composition comprising a first dielectric material and a crosslinking agent carrying at least two azide groups to form a first dielectric layer, iii) curing portions of the first dielectric layer by light treatment, iv) removing the uncured portions of the first dielectric layer, and v) removing the portions of the semiconducting layer that are not covered by the cured first dielectric layer, wherein the first dielectric material comprises a star-shaped polymer consisting of at least one polymer block A and at least two polymer blocks B, wherein each polymer block B is attached to the polymer block A, and wherein at least 60 mol % of the repeat units of polymer block B are selected from the group consisting of Formulas (1A), (1B), (1C), (1D), (1E) and (1F), wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently and at each occurrence H or C.sub.1-C.sub.10-alkyl. ##STR00001##

Claims

1. A top-gate, bottom-contact organic field effect transistor on a substrate, which top-gate, bottom-contact organic field effect transistor comprises source and drain electrodes, a semiconducting layer, a cured first dielectric layer, a second dielectric layer and a gate electrode, wherein i) the cured first dielectric layer and the semiconducting layer cover the path between the source and drain electrodes and optionally also partially or completely cover the source and drain electrodes, and ii) the cured first dielectric layer and the semiconducting layer are embedded in the second dielectric layer, wherein the cured first dielectric layer is the reaction product of a composition comprising a first dielectric material and a crosslinking agent carrying a least two azide groups, wherein the first dielectric material comprises a star-shaped polymer consisting of at least one polymer block A and at least two polymer blocks B, wherein each polymer block B is attached to the polymer block A, and wherein at least 60 mol % of the repeat units of polymer block B are selected from the group consisting of ##STR00081## ##STR00082## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently and at each occurrence H or C.sub.1-10-alkyl.

2. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein at least 80 mol % of the monomer units of the polymer block B are selected from the group consisting of ##STR00083## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are H.

3. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein at least 80 mol % of the monomer units of polymer block A are selected from the group consisting of ##STR00084## wherein R.sup.20, R.sup.21, R.sup.22, R.sup.23, R.sup.24, R.sup.25 and R.sup.26 are independently and at each occurrence selected from the group consisting of H, C.sub.6-14-aryl, 5 to 14 membered heteroaryl and C.sub.1-30-alkyl, and R.sup.a is C(O)OH, C(O)OC.sub.1-30-alkyl, C(O)—H, C(O)C.sub.6-14-aryl, C(O)N(C.sub.1-30-alkyl).sub.2, C(O)N(C.sub.6-14-aryl).sub.2, C(O)N(C.sub.1-30-alkyl)(C.sub.6-14-aryl), C(O)—C.sub.6-14-aryl, C(O)—C.sub.1-30-alkyl, O—C.sub.6-14-aryl, O—C.sub.1-30-alkyl, OC(O)C.sub.1-30-alkyl, OC(O)C.sub.6-14-aryl or CN, wherein C.sub.6-14-aryl and 5-14 membered heteroaryl can be substituted with one or more substituents selected from the group consisting of C.sub.1-10-alkyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, OH, O-phenyl, O—C.sub.1-10-alkyl, OC(O)-phenyl, CN and NO.sub.2, and C.sub.1-30-alkyl can be substituted with one or more substituents selected from the group consisting of phenyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, O-phenyl, O—C.sub.1-10-alkyl, OC(O)C.sub.1-10-alkyl, OC(O)-phenyl, Si(C.sub.1-10-alkyl).sub.3, Si(phenyl).sub.3, CN and NO.sub.2, n is an integer from 1 to 3, and L.sup.20 is C.sub.1-10-alkylene, C.sub.2-10-alkenylene, C.sub.2-10-alkynylene, C.sub.6-14-arylene or S(O).

4. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 3, wherein at least 90 mol % of the monomer units of polymer block A is a monomer unit selected from the group consisting of ##STR00085## wherein R.sup.20 and R.sup.21 are independently selected from the group consisting of H and C.sub.6-14-aryl, wherein C.sub.6-14-aryl can be substituted with one or more C.sub.1-10-alkyl, and L.sup.20 is C.sub.6-14-arylene.

5. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein the star-shaped polymer is a triblock polymer consisting of one polymer block A and two polymer blocks B, wherein each polymer block B is attached to the polymer block A, and wherein at least 60 mol % of the monomer units of polymer block B are selected from the group consisting of ##STR00086## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently and at each occurrence H or C.sub.1-4-alkyl, with the proviso that at least one of the monomer units (1A) and (1B) is present, and that the ratio of [mols of monomer units (1A) and (1B)]/[mols of monomer units (1A), (1B), (1C) and (1D)] is at least 30%.

6. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 5, wherein at least 80 mol % of the monomer units of the polymer block B of the triblock polymer are selected from the group consisting of ##STR00087## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are H, with the proviso that at least one of the monomer units (1A) and (1B) is present, and that the ratio of [mols of monomer units (1A) and (1B)]/[mols of monomer units (1A), (1B), (1C) and (1D)] is at least 70%.

7. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 5, wherein at least 80 mol % of the monomer units of polymer block A of the triblock polymer are selected from the group consisting of ##STR00088## wherein R.sup.20, R.sup.21, R.sup.22, R.sup.23, R.sup.24, R.sup.25 and R.sup.26 are independently and at each occurrence selected from the group consisting of H, C.sub.6-14-aryl, 5 to 14 membered heteroaryl and C.sub.1-30-alkyl, and R.sup.a is C(O)OH, C(O)OC.sub.1-30-alkyl, C(O)—H, C(O)C.sub.6-14-aryl, C(O)N(C.sub.1-30-alkyl).sub.2, C(O)N(C.sub.6-14-aryl).sub.2, C(O)N(C.sub.1-30-alkyl)(C.sub.6-14-aryl), C(O)—C.sub.6-14-aryl, C(O)—C.sub.1-30-alkyl, O—C.sub.6-14-aryl, O—C.sub.1-30-alkyl, OC(O)C.sub.1-30-alkyl, OC(O)C.sub.6-14-aryl or CN, wherein C.sub.6-14-aryl and 5 to 14 membered heteroaryl can be substituted with one or more substituents selected from the group consisting of C.sub.1-10-alkyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, OH, O-phenyl, O—C.sub.1-10-alkyl, OC(O)C.sub.1-10-alkyl, OC(O)-phenyl, CN and NO.sub.2, and C.sub.1-30-alkyl can be substituted with one or more substituents selected from the group consisting of with phenyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, O-phenyl, O—C.sub.1-10-alkyl, OC(O)C.sub.1-10-alkyl, OC(O)-phenyl, Si(C.sub.1-10-alkyl).sub.3, Si(phenyl).sub.3, CN and NO.sub.2, n is an integer from 1 to 3.

8. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 7, wherein at least 80 mol % of the monomer units of polymer block A of the triblock polymer are monomer units selected from the group consisting of ##STR00089## wherein R.sup.20 and R.sup.21 are independently selected from the group consisting of H and C.sub.6-14-aryl, wherein C.sub.6-14-aryl can be substituted with one or more C.sub.1-10-alkyl.

9. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein the weight ratio of polymer block A/total polymer blocks B is from 60/40 to 96/4.

10. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein the star-shaped polymers have a number average molecular weight Mn of at least 60000 g/mol and a weight average molecular weight Mw of at least 70000 g/mol, both as determined by gel permeation chromatography.

11. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein the crosslinking agent carrying at least two azide groups is a crosslinking agent carrying two azide groups and is of formula ##STR00090## wherein a is 0 or 1, R.sup.50 is at each occurrence selected from the group consisting of H, halogen, SO.sub.3M and C.sub.1-20-alkyl, which C.sub.1-20-alkyl can be substituted with one or more halogen, wherein M is H, Na, K or Li, and L.sup.50 is a linking group.

12. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 1, wherein the second dielectric layer comprises a composition comprising a second dielectric material.

13. The top-gate, bottom-contact organic field effect transistor on a substrate of claim 12, wherein the cured first dielectric layer and the semiconducting layer partially or completely cover the source and drain electrodes.

14. A top-gate, bottom-contact organic field effect transistor on a substrate, which top-gate, bottom-contact organic field effect transistor comprises source and drain electrodes, a semiconducting layer, a cured first dielectric layer, a second dielectric layer and a gate electrode, wherein i) the cured first dielectric layer and the semiconducting layer cover the path between the source and drain electrodes and optionally also partially or completely cover the source and drain electrodes, and ii) the cured first dielectric layer and the semiconducting layer are embedded in the second dielectric layer, wherein the semiconducting layer comprises an organic semiconducting material comprising at least one diketopyrrolopyrrole-based material, wherein the diketopyrrolopyrrole-based material is either i) a diketopyrrolopyrrole-based polymer comprising units of formula ##STR00091## wherein R.sup.30 is at each occurrence C.sub.1-30-alkyl, C.sub.2-30-alkenyl or C.sub.2-30-alkynyl, wherein C.sub.1-30-alkyl, C.sub.2-30-alkenyl and C.sub.2-30-alkynyl can be substituted by one or more —Si(R.sup.b).sub.3 or —Oi(R.sup.b).sub.3, or one or more CH.sub.2 groups of C.sub.1-30-alkyl, C.sub.2-30-alkenyl and C.sub.2-30-alkynyl can be replaced by —Si(R.sup.b).sub.2- or -[Si(R.sup.b).sub.2—O].sub.a—Si(R.sup.b).sub.2-, wherein R.sup.b is at each occurrence C.sub.1-10-alkyl, and a is an integer from 1 to 20, o and m are independently 0 or 1, and Ar.sup.1 and Ar.sup.2 are independently arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl or heteroaryl, which C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl and heteroaryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl, L.sup.1 and L.sup.2 are independently selected from the group consisting of ##STR00092## ##STR00093## wherein Ar.sup.3 is at each occurrence arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl or heteroaryl, which C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl and heteroaryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl; and wherein adjacent Ar.sup.3 can be connected via a CR.sup.cR.sup.c, SiR.sup.cR.sup.c or GeR.sup.cR.sup.c linker, wherein R.sup.c is at each occurrence H, C.sub.1-30-alkyl or aryl, which C.sub.1-30-alkyl and aryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl, p is at each occurrence an integer from 1 to 8, and Ar.sup.4 is at each occurrence aryl or heteroaryl, wherein aryl and heteroaryl can be substituted with one or more C.sub.1-30-alkyl, O—C.sub.1-30-alkyl or phenyl, which phenyl can be substituted with C.sub.1-20-alkyl or O—C.sub.1-20-alkyl, or ii) a diketopyrrolopyrrole-based small molecule of formulae (8) or (9) ##STR00094## wherein R.sup.31 is at each occurrence C.sub.1-30-alkyl, C.sub.2-30-alkenyl or C.sub.2-30-alkynyl, wherein C.sub.1-30-alkyl, C.sub.2-30-alkenyl and C.sub.2-30-alkynyl can be substituted by —Si(R.sup.d).sub.3 or —OSi(R.sup.d).sub.3, or one or more CH.sub.2 groups of C.sub.1-30-alkyl, C.sub.2-30-alkenyl and C.sub.2-30-alkynyl can be replaced by —Si(R.sup.d).sub.2- or -[Si(R.sup.d).sub.2—O].sub.a—Si(R.sup.d).sub.2-, wherein R.sup.d is at each occurrence C.sub.1-10-alkyl, and a is an integer from 1 to 20, R.sup.32 is H, CN, C.sub.1-20-alkyl, C.sub.2-20-alkenyl, C.sub.2-20-alkynyl, O—C.sub.1-20-alkyl, aryl or heteroaryl, which C.sub.1-20-alkyl, C.sub.2-20-alkenyl, C.sub.2-20-alkynyl, O—C.sub.1-20-alkyl, aryl and heteroaryl can be substituted with one or more C.sub.1-6-alkyl, O—C.sub.1-6-alkyl or phenyl, x and y are independently 0 or 1, and Ar.sup.5 and Ar.sup.6 are independently arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl or heteroaryl, which C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl and heteroaryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl; L.sup.3 and L.sup.4 are independently selected from the group consisting of ##STR00095## ##STR00096## wherein Ar.sup.7 is at each occurrence arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl or heteroaryl, which C.sub.1-30-alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, O—C.sub.1-30-alkyl, aryl and heteroaryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl; and wherein adjacent Ar.sup.7 can be connected via an CR.sup.eR.sup.e, SiR.sup.eR.sup.e or GeR.sup.eR.sup.e linker, wherein R.sup.e is at each occurrence H, C.sub.1-30-alkyl or aryl, which C.sub.1-30-alkyl and aryl can be substituted with one or more C.sub.1-20-alkyl, O—C.sub.1-20-alkyl or phenyl, q is at each occurrence an integer from 1 to 8, and Ar.sup.8 is at each occurrence aryl or heteroaryl, wherein aryl and heteroaryl can be substituted with one or more C.sub.1-30-alkyl, O—C.sub.1-30-alkyl or phenyl, which phenyl can be substituted with C.sub.1-20-alkyl or O—C.sub.1-20-alkyl.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows an exemplary process for the preparation of a top gate organic field effect transistor of the present invention. In step 1 the source and drain electrodes are applied to the substrate. In step 2 the composition comprising an organic semiconducting material is applied in order to form an organic semiconducting layer. In step 3 the composition comprising the first dielectric material and the crosslinking agent carrying at least two azide groups is applied in order to form a first dielectric layer. In Step 4, portions of the first dielectric layer (1.sup.st GI) are treated with light in order to form a cured first dielectric layer. In step 5 uncured portions of the first dielectric layer are removed. In step 6, the portions of the organic semiconducting layer not covered by the cured first dielectric layer are removed. In step 7 a second dielectric layer (2.sup.nd GI) is applied in a way that the first dielectric layer and the organic semiconducting layer are embedded in the second dielectric layer. In step 8, a gate electrode is applied on top of the second dielectric layer.

(2) FIG. 2 shows the cured first dielectric layer after development.

(3) FIG. 3 shows the cured first dielectric layer as resist after the removal of the portions of the semiconducting layer not covered by the cured first dielectric layer.

(4) FIG. 4 shows the characteristics of the top gate organic field effect transistor of example 3 measured with a Keithley 4200-SCS semiconductor characterization system. The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the organic field effect transistor at a source voltage V.sub.ds of −3 V respectively, −30 V is shown in FIG. 4a. The drain current I.sub.ds in relation to the drain voltage V.sub.ds (output curve) for the organic field effect transistor at a gate voltage V.sub.gs of 0 V, −10 V, −20V and −30 V is shown in FIG. 4b.

EXAMPLES

Example 1

(5) Preparation of a star-shaped polymer, which is a triblock polymer having a styrene-based inner block and two butadiene-based outer blocks with a mass ratio styrene:butadiene of 90:10 and an amount of 1,2-addition of butadiene in the polybutadiene blocks of 73% based on the total amount of butadiene in the polybutadiene block

(6) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 4872 ml (3800 g) cyclohexane, 256 mL (200 g) THF and 1 g 1,1-diphenylethylene (DPE) were heated to 30° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.8 ml). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 76 mL (50 g) butadiene were added under stirring. The temperature was kept at 60° C. controlled by the reactor jacket temperature after 20 min 990 ml (900 g) styrene was added slowly to keep the temperature at 50° C. by jacket counter-cooling. After 25 min another 76 mL (50 g) butadiene were added. After 20 min 1.15 mL isopropanol was added and further stirred for 10 min. The colorless solution was transferred into two 5 Liter canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(7) Workup

(8) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, triblock polymer P1, had the following characteristics: Mn=220000 g/mol. Mw=330000 g/mol (as determined by gel-permeation chromatography with polystyrene standards). PDI 1.5. Amount of 1,2-addition of butadiene in the polybutadiene blocks=73% (as determined by .sup.1H-NMR) based on the total amount of butadiene in the polybutadiene block.

Example 2

(9) Preparation of Compositions A and B

(10) Composition A is a solution of 8% by weight of P1 prepared as described in example 1 as first dielectric material in a mixture of propylene glycol monomethyl ether acetate (PGMEA) and cyclopentanone (CP) (70/30), and 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluorophenyl)ethynyl]-9-heptyl-9-hexyl-fluorene as crosslinking agent carrying at least two azide groups based on the weight of P1. Composition A was prepared by mixing P1, the crosslinking agent and the solvent.

(11) Composition B is a solution of 0.75% by weight of the diketopyrrolopyrrole polymer of example 4 of WO2010/049321 as organic semiconducting material in toluene. Formulation B was filtered through a 0.45 micrometer polytetrafluoroethylene (PTFE).

Example 3

(12) Preparation of a Top-Gate, Bottom-Contact Organic Field Effect Transistor Comprising Composition A and Composition B

(13) Gold was sputtered on a polyethylene terephthalate substrate (PET) and patterned using lithography. The obtained source and drain electrodes had a thickness of approximately 50 nm. The channel length was 10 μm and the channel width was 250 μm. Composition B prepared as described in example 2 was applied on the source and drain electrodes by spin coating (1000 rpm, 30 seconds) and dried at 90° C. on a hot plate for 1 minute to form a 50 nm thick semiconducting layer. Composition A prepared as described in example 2 was applied on the semiconducting layer by spin coating (8000 rpm, 30 seconds), and dried at 80° C. on a hot plate for 2 minutes to form a first dielectric layer having a thickness of 180 nm. A lithographic photomask was aligned on top of the first dielectric layer, and the exposed portions of the first dielectric layer were cured under ambient conditions using light of 365 nm (radiation dosage 20 mJ/cm.sup.2, Suss Mask aligner MA6). The cured first dielectric layer was developed by immersing into propylene glycol methyl ether acetate (PGMEA) for 1 minute followed by blowing with nitrogen and heating at 90° C. for 15 minutes. The portions of the semiconducting layer, which were not covered by the cured first dielectric layer, were etched out by oxygen plasma treatment (100 sccm, 40 W, 2 minutes). Composition A prepared as described in example 2 was applied by spin coating (1500 rpm, 30 seconds) to form a second dielectric film, which was dried at 80° C. on a hot plate for 2 minutes to obtain a 500 nm thick second dielectric layer. The second dielectric layer was cured under ambient conditions using light of 365 nm (radiation dosage 20 mJ/cm.sup.2, Suss Mask aligner MA6). Gate electrodes of gold having a thickness of approximately 50 nm were evaporated through a shadow mask on top of the dielectric layer.

(14) The characteristics of the top gate, bottom contact organic field effect transistor were measured with a Keithley 4200-SCS semiconductor characterization system. The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the organic field effect transistor at a source voltage V.sub.ds of −3 V respectively, −30 V is shown in FIG. 4a. The drain current I.sub.ds in relation to the drain voltage V.sub.ds (output curve) for the organic field effect transistor at a gate voltage V.sub.gs of 0 V, −10 V, −20V and −30 V is shown in FIG. 4b.

(15) The average values of the charge carrier mobility μ, the I.sub.on/I.sub.off ratio (Vgs=−30 V), the onset voltage V.sub.on and the gate leakage current I.sub.g [@ V.sub.gs=−30V, V.sub.ds=−30V] for the organic field effect transistor (OFET) are given in table 1.

(16) TABLE-US-00001 TABLE 1 Characterization of the OFET of example 3. I.sub.g μ I.sub.on/I.sub.off V.sub.on (at V.sub.gs = −30 V, [cm.sup.2/Vs] (V.sub.gs = −30 V) [V] V.sub.ds = −30 V) OFET example 3 0.48 8E+07 4 1.53E−13

(17) The OFET of example 3 shows a very low gate leakage current I.sub.g.

Example 4

(18) Evaluation of the Effect of the Radiation on the Retention of the Cured First Dielectric Layer Formed from Layers Formed from Composition A

(19) Composition A prepared as described in example 2 was filtered through a 1 micrometer filter and applied on a silicon dioxide substrate by spin coating (1800 rpm, 30 seconds). The wet dielectric layer was pre-baked at 90° C. for 2 minutes on a hot plate to obtain a 400 nm thick layer. The dielectric layer was UV-cured using 365 nm (dose of 100 mJ/cm.sup.2) under ambient conditions.

(20) Development of the dielectric layer was done by immersing the dielectric layer into a mixture of propylene glycol monomethyl ether acetate (PGMEA) and cyclopentanone (CP) (70/30) for 1 minute followed by heating at 90° C. for 5 minutes. The thickness of the dielectric layer was measured after curing before development (d1) and after development (d2) using Veeco Dektak 150 to obtain the film retention ratio (d2/d1). The film retention ratios (d2/d1) were determined.

(21) The results are shown in table 2.

(22) TABLE-US-00002 TABLE 2 styrene:butadiene cross-linker polymer Mn Mw 1,2-addition d2/d1 Polymer [g:g] [%].sup.a type [g/mol] [g/mol] butadiene [%] [%] P1 90:10 3 triblock 220000 330000 73 81

(23) The cured dielectric layer formed from composition A shows a high film retention.