Superior Photocurrent of Quantum Dot Sensitized Solar Cells Based on PbS : In/CdS Quantum Dots

PbS : In and CdS quantum dots (QDs) are sequentially assembled onto a nanocrystalline TiO2 film to prepare a PbS : In/CdS cosensitized photoelectrode for QD sensitized solar cells (QDSCs). The results show that PbS : In/CdS QDs have exhibited a significant effect in the light harvest and performance of the QDSC. In the cascade structure of the electrode, the reorganization of energy levels between PbS and TiO2 forms a stepwise structure of band-edge levels which is advantageous to the electron injection into TiO2. Energy conversion efficiency of 2.3% is achieved with the doped electrode, under the illumination of one sun (AM1.5, 100 mW cm2). Besides, a remarkable short circuit current density (up to 23 mA·cm−2) is achieved in the resulting PbS : In/CdS quantum dot sensitized solar cell, and the related mechanism is discussed.