Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices

Photovoltaic performance of the hybrid devices consisting of polymer/fullerene/ZnO nanorod array was studied. The dependence of the photovoltaic performance on the ZnO nanorod length and the organic layer thickness was investigated, and it is concluded that the ZnO nanorod array plays an important role in collecting photogenerated electrons and acts as a conducting path to the indium tin oxide electrode. Fill factor of the devices increased from 38% to 50% when the array of the ZnO nanorods was introduced, which directly contributed to the improvement of the power conversion efficiencies up to 2.7%. As the peak absorption of the device reaches > 97% in a transmitting geometry, the results shown here give us insights toward designing the devices with efficient utilization of the incident light.