Graded SnO2 boosts n-i-p perovskite cells to record efficiency

Researchers report a continuously graded n+/n-doped SnO2 electron-transport layer created via ligand-competitive binding, establishing a built-in electric field that reduces band offsets and speeds electron extraction in n-i-p perovskite solar cells, suppressing cross-interface recombination and achieving a certified steady-state PCE of 27.17% (27.50% in reverse), the highest for this architecture, with scalable devices reaching 25.79% (1 cm2) and 23.33% (16.02 cm2 module).