Fig. 1

Comparison of efficiency and research progress between Pb-based and Sn–Pb mixed based perovskite solar cells (PSCs). a Comparison of best efficiency by year of Pb-based and Sn–Pb mixed PSCs. b Number of publications by year of Pb-based and Sn–Pb mixed PSCs. c The reported efficiencies (left axis) of Sn–Pb mixed PSCs (dots on a graph). The larger, colorful dots above the line represent the highest efficiencies in each period and are important findings that distinguish research trends. The relative efficiency degree between Pb-based and Sn–Pb mixed PSCs (right axis). The schematic diagrams below show representative variables for each corresponding period of the research trend [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40]