Charge Separation Interfaces in Polymer Photovoltaic Devices Hybridized with ZnO Nanorod Arrays

The contributions of different charge separation interfaces were studied in bulk-heterojunction photovoltaic devices based on poly(3-hexylthiophene) (P3HT):(6,6)-phenyl C 61 butyric acid methyl ester (PCBM) hybridized with ZnO nanorod arrays. Quantitative analysis of the performance dependence of the devices on ZnO nanorod length revealed that charge separation is much more effective at the interface of P3HT/PCBM than at that of organic/ZnO, i.e., ZnO nanorods mainly function as efficient electron transport paths. Although the absorption of long ZnO nanorods causes a slight decrease in photocurrent in the UV region, the improvement in fill factor induced by the antenna effect of the ZnO nanorod arrays surpasses that induced by the filter effect, resulting in the high performance of hybrid devices.