OPTICALLY INDUCED TRANSIENT CONDUCTIVITY IN QUASI-METALLIC DCNQI RADICAL-ION SALTS

Multi-component conductivity changes in metallic radical ion salt film s are induced by optical excitation. First experiments on polycrystall ine films of the 2,5-dimethyl-dicyanoquinonediimine copper salt, (DMe- DCNQI)(2)Cu and the corresponding low-dimensional chloro-methyl and br omo-methyl salts, (ClMe-DCNQI)(2)Cu and (BrMe-DCNQI)(2)Cu, respectivel y, are presented. The time response of the conductivity consists of th ree components. These are interpreted a) by a possible contribution of higher conduction bands which might explain the fast response (tau<5 ns), b) by detrapping of charge carriers (tau>40 ns), and c) by a temp erature effect (tau approximate to 1 ms). In single crystals, the fast response is also detected, while the other contributions are less pro nounced.