The effect of C60 on the ZnO-nanorod surface in organic-inorganic hybrid photovoltaics

The electrical property of the organic-inorganic heterojunctions is one of the important factors affecting the performance of hybrid photovoltaic devices. We introduce a good electron conductor. C-60, to modify the surface of ZnO-nanorod arrays in a ZnO-nanorod/poly(3-hexylthiophene):(6,6)-phenyl C-61 butyric acid methyl ester (ZnO/P3HT:PCBM) hybrid photovoltaic structure. We found that there is similar to 40% and similar to 15% increment in the short circuit current (J(SC)) and open circuit voltage (V-OC), respectively, for the device after C-60, modification. By probing the carrier dynamics and the surface property of ZnO-nanorods, the presence of the C-60 layer assists the exciton separation and passivates part of the defect states on the ZnO-nanorod surface. The charge transport property at the ZnO/polymer blend interface is, therefore, improved. As a result, higher charge concentration can transfer from the polymer blend to the ZnO-nanorods more effectively and subsequently travel to electrodes leading to the improved performance in the photovoltaic device. (C) 2010 Elsevier B.V. All rights reserved.