Transient photocurrent in sexithiophene-based photovoltaic cells

Evidence for photovoltaic behaviour of sexithiophene sandwich cell is shown through I–V characterisation in dark and under illumination. Then transient measurements were performed under short laser pulse excitation. Transient photocurrent, which vanishes rapidly, could not be accounted for by a simple exponential decay. We used a theoretical model in which we resolved the kinetic equations, which govern the time evolution of carriers in the device. The best agreement of the model with the experiment allows us to reach the life time of the carriers (τn≈1 μs, τp≈10 μs) and the interaction coefficient electrons plus holes, R≈2.5×10−9 cm3 s−1.