Light-induced halide segregation limits the photovoltaic performance and stability of wide-bandgap perovskite solar cells and tandem cells. Achieving hybrid 2D/3D heterostructures through solution post-processing is a typical strategy to improve the efficiency and stability of perovskite solar cells. However, traditional solution post-processing is not optimal for methylammonium-free and cesium/bromide-rich wide-bandgap PSCs due to the composition-dependent sensitivity of surface reconstruction.
To solve this problem, Professor Tan Hairen of Nanjing University developed a general three-dimensional to two-dimensional perovskite conversion method to achieve preferential growth of wider dimensions (n ≥ 2) on top of the wide-bandgap perovskite layer (1.78 eV).
The technique involves depositing clear thin layers of MAPbI3 via a steam-assisted two-step process and then converting them into two-dimensional structures. This 2D/3D heterostructure can suppress photoinduced halide segregation, reduce nonradiative interface recombination, and promote charge extraction.
The wide-bandgap perovskite solar cell exhibits a championship-winning power conversion efficiency of 19.6% and an open-circuit voltage of 1.32 V. By integrating with the thermally stable FAPb0.5Sn0.5I3 narrow-bandgap perovskite, the all-perovskite tandem solar cell exhibits a stable PCE of 28.1% after 855 h of continuous 1-sun illumination and retains 90% of the initial performance.
Wen, J., Zhao, Y., Wu, P. et al. Heterojunction formed via 3D-to-2D perovskite conversion for photostable wide-bandgap perovskite solar cells. Nat Commun 14, 7118 (2023).
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