Effect of Li-doped TiO2 layer on the photoelectric performance of carbon-based CsPbIBr2 perovskite solar cell

Abstract

Carbon-based CsPbIBr2 perovskite solar cells (PSCs) have attracted much attention due to their excellent photoelectric properties and low cost fabrication processes. The TiO2 has been diffusely employed as electron-transporting layer (ETL) for carbon-based CsPbIBr2 PSC. However, the lower electron mobility for TiO2 restricts the performance improvement. The tactics of ion doping is normally used to improve the ETL performance. In this study, Li-doped TiO2 (Li: TiO2) is used as a novel ETL for carbon-based planar CsPbIBr2 PSC. There is no change in the optical band gap of TiO2 after the incorporation of Li. However, Li-doping can effectively improve the crystallinity of TiO2 film and reduce the dark current and charge recombination of CsPbIBr2 PSC. Comparing with the TiO2-based CsPbIBr2 PSC, the efficiency of CsPbIBr2 PSC with the Li: TiO2 ETL increases from 6.63% to 8.09%. Additionally, the use of the Li: TiO2 ETL also has a positive impact on the long-term stability of the CsPbIBr2 PSC. This work indicates that ion doping can offer a new route to produce effective ETL for the development of highly-efficient CsPbIBr2 solar cell with a interface engineering concept.