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.