Photovoltages in tetracene films

Abstract

Photovoltaic measurements were made on vacuum-evaporated tetracene films sandwiched between an aluminium and a gold electrode. For polychromatic illumination in air open-circuit voltages of up to 1.2 V were observed with the gold electrode positive. The best power conversion efficiency was better than 10-4%. Two modes of carrier production were distinguished, the first resulting from photon absorption in the first tetracene singlet-singlet electronic transition, and the second associated with lower energy red light photons.     Persistent voltages were also found to be generated in the dark, the magnitudes of both these and the photovoltages being reversibly increased by the presence of air.