In this paper, the ZnO nanorod arrays (NRAs) with a diameter of 50nm and a length of 250 nm were synthesized by chemical bath deposition method. Two devices with structures of ITO (indium tin oxides)/ZnO/poly-(3-hexylthiophene) (P3HT)/Au and ITO/ZnO@ZnS/P3HT/Au were fabricated and their performances were tested and evaluated separately. The I-V curves were measured for discussion of the threshold voltage, series resistance, reverse leakage current, and rectification ratio. Results show that the device with modified ZnO shows a decline in the threshold voltage, series resistance and reverse leakage current, but has an enhanced rectification ratio. The effect of ZnS coating on the improvement of conductive properties of the device could be attributed to the suppression of the non-radiative recombination of surface defects as shown by means of photoluminescence spectrum.