Charge transporting semi-conducting material and electronic device comprising it

1. A charge transporting semi-conducting material comprising:

a) optionally at least one electrical dopant, and

b) a branched or cross-linked charge transporting polymer comprising 1,2,3-triazole cross-linking units of at least one of the general formulae Ia and/or Ib,

wherein

aa) Pol 1 -Pol 4 are independently selected chains of the charge-transporting polymer,

bb) X 1 , X 2 , X 3 , and X 4 are independently selected spacer units or, independently, represent direct bonding of Pol 1 -Pol 4 to the 1,2,3-triazole ring,

cc) each of R and R′ is independently selected from H, halogen, or a carbon-containing group,

wherein the charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalised electrons,

the charge transporting semi-conducting material being obtainable by a process comprising:

i) providing a solution containing

aaa) a first precursor charge transporting polymer comprising at least one covalently attached azide group and optionally at least one acetylenic group; and/or a second precursor charge transporting polymer comprising at least one covalently attached acetylenic group and optionally at least one azide group; and optionally at least one crosslinking agent comprising at least two functional groups selected from azide and/or acetylenic group,

bbb) optionally at least one electrical dopant,

ccc) at least one solvent,

ii) depositing the solution on a substrate,

iii) removing the solvent, and

iv) reacting the azide and acetylenic groups to effect crosslinking,

wherein at least one of the first and second precursor charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalised electrons.

2. Charge transporting semi-conducting material according to claim 1 , wherein the average number of azide and/or acetylenic groups per molecule in each of the first precursor charge transporting polymer, the second precursor charge transporting polymer, and the crosslinking agent is greater than 2.

3. Charge transporting semi-conducting material according to claim 1 , wherein, in the pending side group, the conjugated system of delocalized electrons is comprised in a carbocyclic or heterocyclic structural moiety.

4. Charge transporting semi-conducting material according to claim 3 , wherein the conjugated system of delocalized electrons comprised in the carbocyclic or heterocyclic structural moiety is aromatic.

5. Charge transporting semi-conducting material according to claim 4 , wherein the pending side group comprises at least two rings which are independently selected from aromatic and heteroaromatic rings.

6. Charge transporting semi-conducting material according to claim 1 , wherein the pending side group comprises at least one trivalent nitrogen atom.

7. Charge transporting semi-conducting material according to claim 6 , wherein the trivalent nitrogen atom is substituted with three carbocyclic or heterocyclic rings which are independently selected from aromatic and heteroaromatic rings.

8. Charge transporting semi-conducting material according to claim 6 , wherein the pending side group is selected from

9. Charge transporting semi-conducting material according to claim 1 , wherein the electrical dopant is a p-dopant.

10. Charge transporting semi-conducting material according to claim 1 , wherein the electrical dopant is selected from [3]-radialene compounds, wherein each bridgehead carbon atom is substituted by a nitrile group, C 6 -C 14 perfluorinated aryl, or C 2 -C 14 perfluorinated heteroaryl, wherein up to three fluorine atoms in the perfluorinated substituents may optionally be replaced by groups independently selected from nitrile or trifluoromethyl.

11. Charge transporting semi-conducting material according to claim 1 , wherein the step of reacting the azide and acetylenic groups comprises heating.

12. Charge transporting semi-conducting material according to claim 1 , wherein the average number of azide and/or acetylenic groups per molecule in each the first precursor charge transporting polymer, the second precursor charge transporting polymer and the crosslinking agent is greater than 2.05.

13. An electronic device comprising a semi-conducting layer comprising the charge transporting semi-conducting material according to claim 1 .

14. A process for preparing the charge transporting semi-conducting material according to claim 1 , comprising the steps of:

i) providing a solution comprising

a) a first precursor charge-transporting polymer comprising at least one covalently attached azide group and optionally at least one acetylenic group; and/or a second precursor charge-transporting polymer comprising at least one covalently attached acetylenic group and optionally one azide group; and optionally at least one crosslinking agent comprising at least two functional groups selected from azide and/or acetylenic group,

b) optionally at least one electrical dopant,

c) at least one solvent,

ii) depositing the solution on a substrate,

iii) removing the solvent, and

iv) reacting the azide and acetylenic groups to effect crosslinking,

wherein at least one of the first and second precursor charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalized electrons.

15. The process for preparing the charge transporting semi-conducting material according to claim 14 , wherein the step of reacting the azide and acetylenic groups comprises heating.

16. A branched or cross-linked charge transporting polymer comprising 1,2,3-triazole cross-linking units of at least one of the general formulae Ia and/or Ib,

wherein

aa) Pol 1 -Pol 4 are independently selected chains of the charge-transporting polymer,

bb) X 1 , X 2 , X 3 , and X 4 are independently selected spacer units or, independently, represent direct bonding of Pol 1 -Pol 4 to the 1,2,3-triazole ring,

cc) each of R and R′ is independently selected from H, halogen or a carbon-containing group,

wherein the charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalised electrons, and

wherein the charge transporting polymer comprises at least one covalently attached azide group and optionally at least one acetylenic group.

17. The branched or cross-linked charge transporting polymer according to claim 16 , wherein, in the pending side group, the conjugated system of delocalized electrons is comprised in a carbocyclic or heterocyclic structural moiety.

18. The branched or cross-linked charge transporting polymer according to claim 17 , wherein the conjugated system of delocalized electrons comprised in the carbocyclic or heterocyclic structural moiety is aromatic.

19. The branched or cross-linked charge transporting polymer according to claim 18 , wherein the pending side group comprises at least two rings which are independently selected from aromatic and heteroaromatic rings.

20. The branched or cross-linked charge transporting polymer according to claim 16 , wherein the pending side group comprises at least one trivalent nitrogen atom.

21. The branched or cross-linked charge transporting polymer according to claim 20 , wherein the trivalent nitrogen atom is substituted with three carbocyclic or heterocyclic rings which are independently selected from aromatic and heteroaromatic rings.

22. The branched or cross-linked charge transporting polymer according to claim 20 , wherein the pending side group is selected from

23. A branched or cross-linked charge transporting polymer comprising 1,2,3-triazole cross-linking units of at least one of the general formulae Ia and/or Ib,

wherein

aa) Pol 1 -Pol 4 are independently selected chains of the charge-transporting polymer,

bb) X 1 , X 2 , X 3 , and X 4 are independently selected spacer units or, independently, represent direct bonding of Pol 1 -Pol 4 to the 1,2,3-triazole ring,

cc) each of R and R′ is independently selected from H, halogen or a carbon-containing group,

wherein the charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalised electrons, and

wherein the charge transporting polymer comprises at least one covalently attached acetylenic group and optionally at least one azide group.

24. The branched or cross-linked charge transporting polymer according to claim 23 , wherein, in the pending side group, the conjugated system of delocalized electrons is comprised in a carbocyclic or heterocyclic structural moiety.

25. The branched or cross-linked charge transporting polymer according to claim 24 , wherein the conjugated system of delocalized electrons comprised in the carbocyclic or heterocyclic structural moiety is aromatic.

26. The branched or cross-linked charge transporting polymer according to claim 25 , wherein the pending side group comprises at least two rings which are independently selected from aromatic and heteroaromatic rings.

27. The branched or cross-linked charge transporting polymer according to claim 23 , wherein the pending side group comprises at least one trivalent nitrogen atom.

28. The branched or cross-linked charge transporting polymer according to claim 27 , wherein the trivalent nitrogen atom is substituted with three carbocyclic or heterocyclic rings which are independently selected from aromatic and heteroaromatic rings.

29. The branched or cross-linked charge transporting polymer according to claim 27 , wherein the pending side group is selected from

30. A cross-linked charge transporting polymer comprising 1,2,3-triazole cross-linking units of at least one of the general formulae Ia and/or Ib,

wherein

aa) Pol 1 -Pol 4 are independently selected chains of the charge-transporting polymer,

bb) X 1 , X 2 , X 3 , and X 4 are independently selected spacer units or, independently, represent direct bonding of Pol 1 -Pol 4 to the 1,2,3-triazole ring,

cc) each of R and R′ is independently selected from H, halogen or a carbon-containing group, and

wherein the charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalised electrons.

31. A solution, the solution comprising

a) a first precursor charge-transporting polymer comprising at least one covalently attached azide group and optionally at least one acetylenic group; and/or a second precursor charge-transporting polymer comprising at least one covalently attached acetylenic group and optionally one azide group; and optionally at least one crosslinking agent comprising at least two functional groups selected from azide and/or acetylenic group,

b) at least one electrical dopant, and

c) at least one solvent,

wherein the first precursor charge-transporting polymer and the second precursor charge-transporting polymer are independently selected from those capable of reacting to form a cross-linked charge transporting polymer comprising 1,2,3-triazole cross-linking units of at least one of the general formulae Ia and/or Ib,

wherein

aa) Pol 1 -Pol 4 are independently selected chains of the charge-transporting polymer,

bb) X 1 , X 2 , X 3 , and X 4 are independently selected spacer units or, independently, represent direct bonding of Pol 1 -Pol 4 to the 1,2,3-triazole ring,

cc) each of R and R′ is independently selected from H, halogen or a carbon-containing group, and

wherein at least one of the first and second precursor charge transporting polymer comprises ethylene building units substituted with at least one pending side group comprising a conjugated system of delocalized electrons and the solvent comprises at least 1 wt % of a nitrile compound.