Continuously graded-doped SnO₂ for efficient n–i–p perovskite solar cells

Conventional n–i–p architecture remains a robust platform for scalable perovskite photovoltaics 1,2 , yet its steady-state efficiency has stagnated at ~26% (ref.3), lagging behind p–i–n counterparts 4 . This performance gap arises from persistent non-radiative recombination at textured electron transport layer (ETL)/perovskite interfaces, yet the underlying physical origin remains unclear. …