C. Michot et al., POLYIMIDE POLYETHER MIXED CONDUCTORS AS SWITCHABLE MATERIALS FOR ELECTROCHROMIC DEVICES, Solar energy materials and solar cells, 39(2-4), 1995, pp. 289-299
A new family of redox-active polymers have been obtained by polyconden
sation of alpha,omega-diamino oligopolyethers with various aromatic te
tracarboxylic acid anhydrides. The polyether blocks retain the usual c
ation co-ordination ability leading to solid-state ionic conduction wh
ile the relatively large electron affinity of the bis-imide moieties f
ormed in the block polymers allows the reversible formation of stable
radical anions (circle(-) and circle circle(2-)) in the range 2-2.6 V
vs. Li degrees. Either slow-scan or microelectrode voltammetry indicat
e that the totality of the redox centres in such materials are readily
accessible for all polyether spacer lengths tested (6-22 ether fragme
nts), suggesting both a fast electron-exchange mechanism between anion
radicals and a tendency for self assembly (stacking) of the planar ar
omatic groups. When increasing the number of atoms in the aromatic rin
g, the peak separation became smaller (benzene > naphthalene > perylen
e), resulting ultimately in simultaneous 2-electrons injection. These
materials, due to the high coloration efficiency of the reduced state
and their ready processability in thin films are excellent candidate f
or the realisation of laminated solid-state electrochromic devices.