| abstract |
Compositions containing n (a) at least one 1,4-diketopyrrolo[3,4-c]pyrrole of the formula I, II, IIa, III or IV ##STR1## and (b) an auxiliary redox system from the ferrocyanide, ferrocene or ammonium iron (II) sulfate series in combination with at least one conductive salt (c), where, in the formula I, n R and R 2 are, for example, --H and R 1 is --SO 3 Na, n in the formulae II and IIa, R and R 3 are, for example, --H, R 1 is --SO 3 H and p is 3, n in the formula III, R 4 and R 5 are, for example, phenyl and R 6 and R 7 are, for example, methyl, and n in the formula IV R 8 and R 9 are, for example, phenyl, n are suitable as electrochromic materials in display systems. |