Temperature dependence of photocarrier generation in poly-p-phenylene vinylene

We report on the variations of the photocurrent with temperature in poly-p-phenylene vinylene (PPV) under helium. Large differences in the build-up and decay kinetics are observed between room temperature and 77 K. At high temperature the photocurrent variations are very slow. When the temperature decreases the variations are more rapid. The temperature dependence of the photocurrent shows three distinct regions. The behavior at high temperature can be described with the Continuous Time Random Walk model. In this case the suggested species are some interchain Bound Polaron Pairs accumulated in time under illumination. At very low temperature the behavior can be explained by a trapping process (short lifetime) near the conduction band.