Simultaneously Enhanced Efficiency and Stability of Perovskite Solar Cells with TiO2@CdS Core-Shell Nanorods Electron Transport Layer

Both demands of stability and efficiency constitute the gargantuan barriers of perovskite solar cells (PSCs), hampering the academic communities and industrial production. Herein, it is demonstrated that, after depositing optimized CdS shell layers on TiO2 nanorod arrays (NAs) by a simple and rapid chemical bath method at room temperature, the efficiency and stability of PSCs are simultaneously enhanced. The PSCs based on TiO2/CdS core-shell NAs achieve higher power conversion efficiency up to 17.71%, compared to 15.93% of the pristine TiO2 NAs-based cells. Especially, the stability of the PSCs is prominently improved after optimized CdS layer modification without encapsulation. The significant enhancement of both efficiency and stability are mainly ascribed to that the type-II structure of TiO2/CdS coaxial nanorods can suppress recombination, and the oxygen vacancies on TiO2 surfaces are not directly contacted with perovskite layers. The surface modification on TiO2 NAs opens up an alternative approach toward improving the performance and stability of PSCs.