Electrochromic display element, optical filter, lens unit, and imaging device

1. An electrochromic display element comprising:

a pair of electrodes; and

an electrochromic layer disposed between the electrodes, the electrochromic layer containing:

a solvent;

a supporting electrolyte:

an anodic electrochromic molecule comprising a triarylamine derivative; and

a cathodic electrochromic molecule comprising a viologen derivative,

wherein concentrations of the triarylamine derivative and the viologen derivative in the electrochromic layer are each 4 mM or more, and

wherein the viologen derivative comprises a compound represented by the following general formula (5):

where each of R 1 and R 2 independently represents an alkyl or aryl group having 1 to 10 carbon atoms which may have a substituent; each of n and m independently represents 0 or an integer of from 1 to 10; and X represents a monovalent anion selected from the group consisting of ClO 4 ion (ClO 4 - ), PF 6 ion (PF 6 - ), BF 4 ion (BF 4 - ), CF 3 SO 3 ion (OTf - ), (FSO 2 ) 2 N ion (FSI - ), (CF 3 SO 2 ) 2 N ion (TFSI - ), or B(CN) 4 ion (TCB - ).

2. The electrochromic display element according to claim wherein the concentrations of the triarylamine derivative and the viologen derivative in the electrochromic layer are each 8 mM or more.

3. The electrochromic display element according to claim 2 , wherein the concentrations of the triarylamine derivative and the viologen derivative in the electrochromic layer are each 11 mM or more.

4. The electrochromic display element according to claim wherein the triarylamine derivative comprises a benzidine derivative.

5. The electrochromic display element according to claim 4 , wherein the benzidine derivative comprises a compound represented by the following general formula (6):

where each of R 55 to R 58 independently represents a halogen atom, an alkyl group, an alkoxy group, or a phenyl ether group; each of R 59 to R 66 independently represents a hydrogen atom, an alkyl group, or an alkoxy group; and each of R 67 and R 68 independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, or R 67 and R 68 may be bonded with each other to form the following structure when each of R 67 and R 68 represents an alkyl group:

where each of R 1 and R 2 independently represents an alkyl group or an aryl group.

6. The electrochromic display element according to claim 1 , wherein the triarylamine derivative comprises a compound represented by the following general formula (7):

where each of R 1 to R 3 independently represents at least one member selected from the group consisting of a halogen atom, an alkyl group, an alkoxy group, a group in which an aryl group and a heterocyclic group are bonded via a covalent bond, and a group in which an aryl group and a heterocyclic group are ring-condensed; and each of R 4 to R 15 independently represents at least one member selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a group in which an aryl group and a heterocyclic group are bonded via a covalent bond, acid a group in which an aryl group and a heterocyclic group are ring-condensed.

7. The electrochromic display element according to claim 1 , wherein the viologen derivative comprises a compound represented by one of the following structural formulae (4) to (7).

8. The electrochromic display element according to claim 1 , wherein the solvent comprises a benzonitrile derivative.

9. An optical filter comprising the electrochromic display element according to claim 1 .

10. The optical filter according to claim 9 , further comprising an active element coupled to the electrochromic display element.

11. A lens unit comprising the electrochromic display element according to claim 1 .

12. An imaging device comprising:

an imaging optical system comprising an optical path; and

the electrochromic display element according to claim 1 disposed in the optical path.