Study on photo-induced charge transfer in the heterointerfaces of CuInS2/CdS co-sensitized mesoporous TiO2 photoelectrode

CuInS2 and CdS quantum dots (QDs) are sequentially assembled onto mesoporous TiO2 film to prepare a CuInS2/CdS co-sensitized photoelectrode for QD-sensitized solar cell (QDSC) application. Our results show that the performance of a QDSC is strongly dependent on the order of CuInS2 and CdS respected to the TiO2. When CuInS2 is in between TiO2 and CdS, the power conversion efficiency could reach 0.90%, while the efficiency decreased dramatically when the CuInS2 QDs were on top of the layer (0.08%). Surface photovoltage (SPV) measurement revealed that the charge transfer from the cosensitizers toward the TiO2 is much more efficient in the TiO2/CuInS2/CdS electrode rather than in the TiO2/CdS/CuInS2 electrode. From the information on time-resolved photoluminescence (TRPL) technique, it was found that the average photoluminescence (PL) lifetime of TiO2/CuInS2/CdS electrode is shorter than that of the TiO2/CdS/CuInS2 electrode, suggesting the higher carrier transfer rates between the heterointerfaces of CuInS2/CdS and TiO2/QDs. This study reported herein propose an innovative route to investigate the role of heterointerface in the carrier transfer mechanism and enable better design of highly efficient QDSCs. (C) 2016 Elsevier Ltd. All rights reserved.