Using a wafer cut from a Bridgman-grown ingot of CuInSe2 as the p-type monocrystalline absorber substrate, a photovoltaic cell has been fabricated with the layer structure Au-CuInSe2 (p)-CdS-ZnO-In. This device has shown superior photovoltaic performance with an apparent initial effective area conversion efficiency of some 12.5% (11.3% total area efficiency), without an antireflection coating, under direct sunlight, where the irradiance corresponded approximately to 90.5 mW/cm(2). The effective cell area was 12.6 mm(2) (total area 13.8 mm(2)) and the acceptor concentration in the CuInSe2, estimated from a Mott-Schottky plot, was about 1017 cm(-3). However, the photocurrent-capacitance method applied to the cell indicated an electron diffusion length of only about 0.3 mum. (C) 2004 American Vacuum Society.