Photoirradiation effects of poly(p-pyridyl vinylene), PPyV/poly(3-hexylthiophene), P3HT and polypyridine, PPy/poly(2-methoxy-5-dodecyloxy-p-phenylene vinylene), MDOPPV heterostructure photoelectric conversion devices have been investigated. The photovoltaic characteristics of the heterostructure photoelectric conversion device are considerably improved from those in a single-layer photoelectric conversion device. Quenching of photoluminescence both in the PPyV layer film and in the P3HT layer film has been observed in the PPyV/P3HT heterostructure film. The observed photoirradiation effects of the heterostructure device have been discussed in terms of interfacial photoinduced charge transfer between P3HT and PPyV. (C) 2002 Elsevier Science B.V. All rights reserved.