Charge-transporting polymer, composition for organic electroluminescent element, organic electroluminescent element, organic EL display, and organic EL lighting

1. A charge-transporting polymer, comprising a side chain represented by formula (1):

wherein

the benzocyclobutene ring optionally has one or more substituents, and the substituents are optionally bonded to each other to form a ring; and

the spacer represents a group which links the benzocyclobutene ring to a main chain of the charge-transporting polymer through three or more single bonds.

2. The charge-transporting polymer according to claim 1 , wherein the side chain represented by formula (1) is a group represented by formula (2):

wherein the divalent group Q represents a group selected from the group consisting of —CR 1 R 2 —, —O—, —CO—, —NR 3 —, and —S—, and n represents a natural number of 2-30,

R 1 to R 3 each independently represent a hydrogen atom or an alkyl group which optionally has a substituent,

the number n of Qs are the same or different, and

the benzocyclobutene ring in formula (2) optionally has a substituent besides the divalent group Q.

3. The charge-transporting polymer according to claim 2 , wherein the group represented by formula (2) is a group represented by formula (3):

wherein R 1 and R 2 each independently represent a hydrogen atom or an alkyl group which optionally has a substituent, and q represents a natural number of 2-30,

the number q of R 1 s and the number q of R 2 s each independently are the same or different, and

the benzocyclobutene ring in formula (3) optionally has a substituent besides the —(CR 1 R 2 ) q — group.

4. The charge-transporting polymer according to claim 1 , which comprises, as a partial structure, a monovalent or higher valent group which comprises a triarylamine structure.

5. The charge-transporting polymer according to claim 1 , which comprises, as a partial structure, a monovalent or higher valent group which comprises a fluorene ring.

6. The charge-transporting polymer according to claim 1 , which has a weight-average molecular weight (Mw) of 20,000 or higher and a distribution (Mw/Mn) of 2.5 or less, in which Mn represents the number-average molecular weight.

7. The charge-transporting polymer according to claim 1 , which comprises a repeating unit represented by formula (4):

wherein

m represents an integer of 0-3,

Ar 11 and Ar 12 each independently represent a direct bond, an aromatic hydrocarbon group which optionally has a substituent, or an aromatic heterocyclic group which optionally has a substituent,

Ar 13 to Ar 15 each independently represent an aromatic hydrocarbon group which optionally has a substituent or an aromatic heterocyclic group which optionally has a substituent, and

Ar 11 and Ar 12 are not simultaneously direct bonds.

8. The charge-transporting polymer according to claim 1 , wherein a number of groups represented by formula (1) per molecule weight of 1,000 of the polymer is from 0.01 to 3, wherein the molecular weight is a value which is calculated from a molar ratio and a structural formula of feed monomers for the charge-transporting polymer excluding end groups.

9. The charge-transporting polymer according to claim 8 , comprising a group represented by formula (5):

wherein the styryl group optionally has one or more substituents, and the one or more substituents optionally bond to each other to form a ring.

10. A composition for organic electroluminescent element, comprising the charge-transporting polymer according to claim 1 and a solvent.

11. The composition for organic electroluminescent element according to claim 10 , further comprising an electron-accepting compound.

12. An organic electroluminescent element, comprising:

a substrate and, provided thereon,

an anode,

a cathode, and

an organic layer interposed between the anode and the cathode,

wherein the organic layer comprises a layer formed by coating an underlying layer of the organic layer with the composition of claim 10 and then crosslinking the charge-transporting polymer.

13. The organic electroluminescent element according to claim 12 , wherein the layer formed by crosslinking of the charge-transporting polymer is at least one of a hole injection layer and a hole transport layer.

14. The organic electroluminescent element according to claim 12 , further comprising:

a hole injection layer,

a hole transport layer, and

a luminescent layer,

wherein all of the hole injection layer, the hole transport layer, and the luminescent layer are formed by a wet film formation method.

15. An organic EL display, comprising the organic electroluminescent element according to claim 12 .

16. An organic EL lighting, comprising the organic electroluminescent element according to claim 12 .

17. A charge-transporting polymer comprising, a side chain selected from the group consisting of