Transient photoresponse measurements in x-phase of metal-free phthalocyanine photovoltaic cells

Transient response of In/x phase of metal-free phthalocyanine Schottky barrier photovoltaic cells as a function of the applied reverse bias has been investigated under pulse and step illumination conditions. In both cases the dependence of the photoresponse on the applied bias showed the change in shape when the light wavelength was changed. This can be interpreted in the framework of the local carrier generation model in which it is assumed that the carrier generation is dominated by the contribution from the barrier region. In the constant illumination mode, it was clearly demonstrated that the photocurrent has two components—the true photocurrent component and the component caused by changes in the barrier properties. For the true photocurrent component, using strongly absorbed red light for illumination, a saturation was observed which enabled the determination of quantum efficiency of carrier generation in the barrier of 70%.