Hybrid bulk heterojunction solar cells based on poly (3-hexylthiophene) and Z907-modified ZnO nanorods

This work presents hybrid bulk heterojunction solar cells based on blends of Z907-modified ZnO nanorods and poly (3-hexylthiophene) (P3HT). ZnO nanorods were synthesized by a low temperature hydrothermal method and chemically modified with Z907 through a reflux process. Transmission electron microscope, X-ray diffractometer, infrared spectrometer, UV-vis spectrophotometer, fluorescence spectrometer and photovoltaic device measurements were used to study the morphology, structure, dye binding mode, light absorption, charge transfer and device performance of the structures consisting of P3HT polymer in contact with Z907-modified ZnO nanorods. Results show that Z907 grafting improves the compatibility between ZnO nanorods and P3HT and has not substantially altered the crystal structure of ZnO nanorods. In addition, each Z907 molecule is chemically grafted onto the ZnO surface with two carboxylic acid groups in a unidentate binding mode. Moreover, Z907 modification enlarges the visible light absorption range of ZnO/P3HT composite film and enhances the charge transfer efficiency at the P3HT/ZnO interface. The power conversion efficiency of the P3HT/Z907-ZnO solar cells at a Z907 concentration of 0.3 mM under 100 mW/cm(2) of AM 1.5 illumination is 0.21%. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.