W-doped TiO₂ as electron transport layer for high performance solution-processed perovskite solar cells

In this work, W-doped TiO₂, was successfully fabricated, as electron transport layer (ETL) in perovskite solar cells (PSCs) via low-temperature solution-processed method, whose outstanding performances were verified. The experimental results reveal that, W⁶⁺ was doped into the TiO₂ lattice successfully. The improved ETL exhibit significantly improved on conductivity, transport and extraction of photo-generated carriers and less trap-state density as compared with the pristine TiO₂ films. Meanwhile, strengthening the velocity of carrier and collection of sufficient charge can efficiently increase short-circuit current (J_SC) which favor an improved fill factor (FF) and a higher power conversion efficiency (PCE). Our optimized cation–anion-mixed PSC based on W-doped TiO₂ has achieved an efficiency of 18.85%. This improved PCE is almost 28.1% higher than that of the pure TiO₂. This study provides a promising approach to design metal-doped TiO₂ for fabricating high-performance perovskite solar cells.