A screen-printed electron transport layer for efficient air-processed perovskite solar cells

We present a robust and screen-printed electron transport layer (ETL) by modulating a mesoporous TiO₂ scaffold with SnO₂. This hybrid modification strategy simultaneously enhances the electrical conductivity and passivates interfacial defects within the ETL, thereby reducing trap-assisted recombination while improving electron extraction efficiency. Notably, the incorporation of SnO₂ raises the Fermi level and lowers the valence band maximum of TiO₂, resulting in a near-ideal energy-level alignment that facilitates efficient electron extraction and effective hole blocking. The optimized devices, fabricated under ambient conditions, achieve a champion power conversion efficiency of 24.4% and maintain an efficiency of 20.4% even at an ETL thickness of over 1 micron.