TiO2 hierarchical nanowire-P25 particulate composite photoanodes in combination with N-doped mesoporous carbon/Ti counter electrodes for high performance quantum dot-sensitized solar cells

Abstract

The time-consuming transport of photo-generated electrons across conventional photoanode film, composed of disordered P25 TiO2 nanoparticulates, is one of the main bottlenecks to improve the performance of quantum dot-sensitized solar cells (QDSCs). A convenient and effective method was developed for the preparation of high performance photoanodes based on composite paste composed of conventional P25 TiO2 nanoparticulates and TiO2 hierarchical nanowires (HNW) for QDSCs. The shortened transport path in the composite photoanode brings forward suppressed charge recombination processes at the interfaces between photoanode and electrolyte, and improved photovoltaic performance of the resulting solar cells. Through optimizing the composite photoanode and the adoption of N-doped mesoporous carbon/Ti counter electrodes, average power conversion efficiency of Zn-Cu-In-Se (ZCISe) QDSCs was increased from 12.77% corresponding to conventional P25 photoanodes to 13.43% (Jsc = 27.38 mA cm−2, Voc = 0.764 V, and FF = 0.642) corresponding to photoanodes with HNW/P25 weight ratio of 0.1%. Furthermore, this composite photoanode is also effective in improving the photovoltaic performance of QDSCs under different QD sensitizers (such as Zn-Cu-In-S (ZCIS) QDs) as well as different counter electrodes (such as Cu2S/brass).