In this article, we have fabricated photovoltaic devices based on the poly(3-hexylthiophene)–TiO₂nanorod bulk heterojunction. The microscopic mechanisms of charge separation and charge transport in the poly(3-hexylthiophene)–TiO₂nanorod nanocomposites have been investigated by photoluminescence quenching, time-resolved photoluminescence spectroscopy, and time-of-flight mobility measurements. Charge separation and transport efficiency can be improved by adding an adequate amount of TiO₂nanorods in polymer. In addition, the device performance can be further enhanced by thermal annealing or removal of insulating surfactant in the hybrid, giving an optimized device performance of a short circuit current density of 2.62 mA cm⁻², an open circuit voltage of 0.69 V, a fill factor of 0.63 under simulated A.M. 1.5 illumination (100 mW cm⁻²). The corresponding power conversion efficiency under 1 sun is about 1.14%.