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

Abstract CuInS 2 and CdS quantum dots (QDs) are sequentially assembled onto mesoporous TiO 2 film to prepare a CuInS 2 /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 CuInS 2 and CdS respected to the TiO 2 . When CuInS 2 is in between TiO 2 and CdS, the power conversion efficiency could reach 0.90%, while the efficiency decreased dramatically when the CuInS 2 QDs were on top of the layer (0.08%). Surface photovoltage (SPV) measurement revealed that the charge transfer from the cosensitizers toward the TiO 2 is much more efficient in the TiO 2 /CuInS 2 /CdS electrode rather than in the TiO 2 /CdS/CuInS 2 electrode. From the information on time-resolved photoluminescence (TRPL) technique, it was found that the average photoluminescence (PL) lifetime of TiO 2 /CuInS 2 /CdS electrode is shorter than that of the TiO 2 /CdS/CuInS 2 electrode, suggesting the higher carrier transfer rates between the heterointerfaces of CuInS 2 /CdS and TiO 2 /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.