Substituted 1,2,3-triylidenetris(cyanomethanylylidene) cyclopropanes for VTE, electronic devices and semiconducting materials using them

1. A process for preparation of an electrically doped semiconducting material comprising a [3]-radialene p-dopant or for preparation of an electronic device including a layer comprising a [3]-radialene p-dopant, the process comprising the steps:

(i) loading an evaporation source with the [3]-radialene p-dopant and

(ii) evaporating the [3]-radialene p-dopant at an elevated temperature and at a reduced pressure,

wherein the [3]-radialene p-dopant is selected from compounds having a structure according to formula (I)

wherein A 1 and A 2 are independently aryl- or heteroaryl-substituted cyanomethylidene groups,

the aryl and/or heteroaryl is selected independently in A 1 and A 2 from 4-cyano-2,3,5,6-tetrafluorphenyl, 2,3,5,6-tetrafluorpyridine-4-yl, 4-trifluormethyl-2,3,5,6-tetrafluorphenyl, 2,4-bis(trifluormethyl)-3,5,6-trifluorphenyl, 2,5-bis(trifluormethyl)-3,4,6-trifluorphenyl, 2,4,6-tris(trifluormethyl)-1,3-diazine-5-yl, 3,4-dicyano-2,5,6-trifluorphenyl, 2-cyano-3,5,6-trifluorpyridine-4-yl, 2-trifluormethyl-3,5,6-trifluorpyridine-4-yl, 2,5,6-trifluor-1,3-diazine-4-yl and 3-trifluormethyl-4-cyano-2,5,6-trifluorphenyl,

and at least one aryl or heteroaryl is 2,3,5,6-tetrafluorpyridine-4-yl, 2,4-bis(trifluormethyl)-3,5,6-trifluorphenyl, 2,5-bis(trifluormethyl)-3,4,6-trifluorphenyl, 2,4,6-tris(trifluormethyl)-1,3-diazine-5-yl, 3,4-dicyano-2,5,6-trifluorphenyl, 2-cyano-3,5,6-trifluorpyridine-4-yl, 2-trifluormethyl-3,5,6-trifluorpyridine-4-yl, 2,5,6-trifluor-1,3-diazine-4-yl or 3-trifluormethyl-4-cyano-2,5,6-trifluorphenyl,

provided that the heteroaryl in both A 1 and A 2 cannot be 2,3,5,6-tetrafluorpyridine-4-yl at the same time.

2. The process according to claim 1 , wherein the temperature in step (ii) is in the range 100-300° C.

3. The process according to claim 1 , wherein the duration of the step (ii) is at least 100 hours.

4. The process according to claim 1 , wherein in the step (ii), a hole transport material comprising at least one hole transport matrix compound is co-evaporated with the compound having structure (I) and, in a subsequent step (iii), the compound (I) and the hole transport matrix compound are co-deposited to form a semiconducting material.

5. The process according to claim 1 , wherein the step (ii) is carried out at a pressure which is lower than 10 −1 Pa.

6. The process according to claim 1 , wherein compound (I) has reversible redox potential, measured by cyclic voltammetry in acetonitrile against ferrocene/ferricenium reference system, in the range from +0.10 to +0.50 V.

7. A [3]-radialene compound having a structure according to formula (I):

wherein

A 1 and A 2 are independently aryl- or heteroaryl-substituted cyanomethylidene groups, the aryl and/or heteroaryl is selected independently in A 1 and A 2 from 4-cyano-2,3,5,6-tetrafluorphenyl, 2,3,5,6-tetrafluorpyridine-4-yl, 4-trifluormethyl-2,3,5,6-tetrafluorphenyl, 2,4-bis(trifluormethyl)-3,5,6-trifluorphenyl, 2,5-bis(trifluormethyl)-3,4,6-trifluorphenyl, 2,4,6-tris(trifluormethyl)-1,3-diazine-5-yl, 3,4-dicyano-2,5,6-trifluorphenyl, 2-cyano-3,5,6-trifluorpyridine-4-yl, 2-trifluormethyl-3,5,6-trifluorpyridine-4-yl, 2,5,6-trifluor-1,3-diazine-4-yl and 3-trifluormethyl-4-cyano-2,5,6-trifluorphenyl,

and at least one aryl or heteroaryl is 2,3,5,6-tetrafluorpyridine-4-yl, 2,4-bis(trifluormethyl)-3,5,6-trifluorphenyl, 2,5-bis(trifluormethyl)-3,4,6-trifluorphenyl, 2,4,6-tris(trifluormethyl)-1,3-diazine-5-yl, 3,4-dicyano-2,5,6-trifluorphenyl, 2-cyano-3,5,6-trifluorpyridine-4-yl, 2-trifluormethyl-3,5,6-trifluorpyridine-4-yl, 2,5,6-trifluor-1,3-diazine-4-yl or 3-trifluormethyl-4-cyano-2,5,6-trifluorphenyl,

provided that the heteroaryl in both A 1 and A 2 cannot be 2,3,5,6-tetrafluorpyridine-4-yl at the same time.

8. The compound according to claim 7 , having reversible redox potential, measured by cyclic voltammetry in acetonitrile against ferrocene/ferricenium reference system, in the range from +0.10 to +0.50 V.

9. A semiconducting material comprising the compound according to claim 7 and a matrix material comprising at least one hole transport matrix compound.

10. An electronic device comprising, between a first and a second electrode, the semiconducting material according to claim 9 .

11. The electronic device according to claim 10 , which is an organic light emitting diode.

12. The electronic device according to claim 10 , wherein the compound having formula (I) is comprised in a hole injecting layer and/or in a hole transporting layer and/or in a charge generating layer.

13. A semiconducting layer consisting of the semiconducting material according to claim 9 .

14. A semiconducting layer consisting of the compound according to claim 7 .

15. An electronic device comprising, between a first and a second electrode, the semiconducting layer according to claim 14 .

16. The electronic device according to claim 15 , which is an organic light emitting diode.

17. The electronic device according to claim 15 , wherein the compound having formula (I) is comprised in a hole injecting layer and/or in a hole transporting layer and/or in a charge generating layer.

18. Use of the compound according to claim 7 as a p-dopant in a semiconducting material, in a semiconducting layer, or in an electronic device.

19. A process for synthesis of the [3]-radialene compound according to claim 7 ,

wherein a last synthesis step consists of oxidizing a reduced form of the compound of formula (I) to form the compound of formula (I), and the last synthesis step is carried out in a solvent comprising at least one saturated halogenated carboxylic acid.