Incorporating of Lanthanides Ions into Perovskite Film for Efficient and Stable Perovskite Solar Cells.

Since Yan's work, incorporation of some lanthanide elements, such as Eu and Nd, into MAPbI3 layer has been proven to be a powerful strategy on improving the permanence of the perovskite solar cells (PSCs). However, a comprehensive configuration has not been given for different lanthanide elements doping while the mechanism has not been clarified. Herein, the incorporation of various lanthanides ions (Ln3+ = Ce3+ , Eu3+ , Nd3+ , Sm3+ , or Yb3+ ) into perovskite films to largely enhance the performance of PSCs is presented. Arising from the enlarged grain size and crystallinity of perovskite film upon Ln3+ ions doping, the efficiency and stability of PSCs are significantly improved. Extraordinarily, PSCs with Ce3+ doping achieve the best performance, with a champion power conversion efficiency (PCE) of 21.67% in contrast to 18.50% for pristine PSCs, and outstanding long-term and UV irradiation stability. Such high performance of PSCs after Ce3+ doping originates from special Ce3+ /Ce4+ redox pair and the unique 4f-5d absorption in the UV region. Finally, the flexible PSCs with low-temperature preparation are explored. Considering the richer deposition of cerium element in the earth and lower price, the findings may provide new opportunities for developing low-cost, highly efficient, air/UV stable, and flexible PSCs.