Communication: alpha-Thiophene octamer (alpha-8T) is shown to be a suitable material for application as the p-type semiconductor component in photovoltaic devices. Combined with a perylene pigment as the n-type semiconductor, the alpha-8T is used to produce a pn heterojunction cell which exhibits a fill factor of 0.5 and a conversion efficiency of 0.6 % for irradiation of white light, a performance comparable to that reported for copper- and titanyl-phthalocyanine-based devices. The application of alpha-8T would allow vacuum deposition techniques to be used in the production of the cells.