High-Performance and Hysteresis-Free Perovskite Solar Cells Based on Rare-Earth-Doped SnO₂ Mesoporous Scaffold

Tin oxide (SnO₂), as electron transport material to substitute titanium oxide (TiO₂) in perovskite solar cells (PSCs), has aroused wide interests. However, the performance of the PSCs based on SnO₂ is still hard to compete with the TiO₂-based devices. Herein, a novel strategy is designed to enhance the photovoltaic performance and long-term stability of PSCs by integrating rare-earth ions Ln³⁺ (Sc³⁺, Y³⁺, La³⁺) with SnO₂ nanospheres as mesoporous scaffold. The doping of Ln promotes the formation of dense and large-sized perovskite crystals, which facilitate interfacial contact of electron transport layer/perovskite layer and improve charge transport dynamics. Ln dopant optimizes the energy level of perovskite layer, reduces the charge transport resistance, and mitigates the trap state density. As a result, the optimized mesoporous PSC achieves a champion power conversion efficiency (PCE) of 20.63% without hysteresis, while the undoped PSC obtains an efficiency of 19.01%. The investigation demonstrates that the rare-earth doping is low-cost and effective method to improve the photovoltaic performance of SnO₂-based PSCs.