Photoconductivity of polymers with conjugated double bonds

Polymers with conjugated double bonds (conductive polymers) have attracted much attention during the last ten years (1982-92) because of the possibility of producing samples with metallic conductivity by suitable dopants. Much less attention has been paid to the electrical properties of undoped samples which exhibit the electrical characteristics of insulators or semiconductors. These conditions are especially suited for the investigation of low level doping and for the measurement of the light- or radiation induced conductivity. Photoconductivity measurements are especially important since information on the charge carrier dynamics and energetics in the polymer can be obtained. Here the authors wish to report on the photoconductivity of chemically synthesized samples of polypyrrole (PPy) and polythiophene (PT). The structure formulae of these compounds are shown