Sulfur-doped carbon nitride/TiO2 Electron transport layer via glass-assisted annealing for high-efficiency perovskite solar cells

The TiO 2 -based electron transport layer (ETL) holds significant potential for efficient perovskite solar cells (PSCs), yet challenges in interfacial defects and energy alignment limit performance. Herein, sulfur-doped graphitic carbon nitride (SCN) is incorporated into TiO 2 using a rapid glass-assisted annealing method to engineer the ETL. The SCN/TiO 2 composite enhances perovskite crystallization by suppressing PbI 2 secondary phases and improves interfacial compatibility. Additionally, optimized energy-level alignment facilitates electron extraction while reducing non-radiative recombination, as evidenced by photoluminescence and time-resolved spectroscopy. These synergistic effects yield a champion device with a power conversion efficiency (PCE) of 21.02%, surpassing the pristine TiO 2 -based counterpart (18.20%) by 16.6%, alongside elevated open-circuit voltage (V oc = 1.10 V) and short-circuit current density (J sc = 24.98 mA cm -2 ). This work demonstrates the efficacy of S-CN in addressing interfacial limitations, offering a scalable strategy to advance high-efficiency perovskite photovoltaics.