Performance of polymer/ZnO hybrid photovoltaic devices determined by reaction time for oriented ZnO nanorod growth

The performance of hybrid polymer/metal oxide photovoltaic devices based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) and oriented ZnO nanorods is studied. The ZnO nanorods on indium tin oxide-coated glass were prepared by hydrothermal method, where the length and the defect concentration of ZnO nanorods were controlled by the reaction time (Tr) for nanorod growth. Increasing Tr results in longer ZnO nanorods and higher defect concentration. Results show that both photocurrent and electron lifetime have strong dependence on the nanorod length (i.e., growth time) due to the exponential attenuation of incident light intensity in the device, offering a peak conversion efficiency of 0.337% under 1.5 AM illumination for Tr = 120 min. Combinational analyses of the data in this experiment and the previous data for the electrodeposited ZnO nanorods provide the insights into the dependence of the device performance on the intrinsic property of the ZnO nanorods.