Fig. 4: Performance of 2T all-perovskite tandem solar cells with CPGCl doping.

a, b Schematic picture (a) and cross-section SEM image (b) of all-perovskite 2T tandem solar cells. c, d J-V curves (c) and stabilized PCE (d) of the best-performing all-perovskite tandem cell. e EQE curves of the tandem cell. f Histogram of PCEs for 78 tandem cells, the average value was 27.02 ± 0.53%.