Blends of nanocryst. zinc oxide nanoparticles (nc-ZnO) and regioregular poly(3-hexylthiophene) (P3HT) processed from soln. have been used to construct hybrid polymer-metal oxide bulk-heterojunction solar cells. Thermal annealing of the spin-cast films significantly improves the solar-energy conversion efficiency of these hybrid solar cells to .apprx.0.9%. Photoluminescence and photoinduced absorption spectroscopy demonstrate that charge-carrier generation is not quant., because a fraction of P3HT appears not to be in contact with or in close proximity to ZnO. The coarse morphol. of the films, also identified by tapping-mode at. force microscopy, likely limits the device performance. [on SciFinder (R)