Influence of oxygen doping on the photoconductivity of π-conjugated molecules

The effect of oxygen doping on the photoconductivity of sexithiophene and oxotitanylphthalocyanine films on interdigitated electrodes is investigated by studying photocurrent kinetics after pulsed excitation. Photoadsorbed oxygen is found to increase the photoconductivity by forming a charge-transfer complex MO2 with the film molecules. Encounters of excitons with MO2 and electron transfer from the film to an excited MO2 lead to efficient charge carrier separation. The resulting kinetics reproduce the experimental results.