quantum dot electron transport layers for high-performance planar perovskite solar cells*

Organic-inorganic lead halide perovskite solar cells (PSCs) have shown great potential due to rapid development in power conversion efficiency, which has surpassed 23%. The quality of the electron transport layers (ETLs) and hole transport layers can significantly affect the performance of PSCs. Tin Oxide (SnO₂) commonly employed in planar PSCs is a promising material as ETLs. Herein, we facilely synthesize colloidal SnO₂ quantum dots (QDs) at room temperature and control the carrier concentration of SnO₂ QD ETLs at different annealing temperature to achieve high performance PSCs. By optimizing the electron density of SnO₂ QD ETLs, we can achieve a champion stabilized power output of 20.32% for the planar PSCs using triple cation perovskite absorber and 19.73% for those using CH₃NH₃PbI₃-based system. Our results demonstrate the promise of carrier concentration-controlled SnO₂ QD ETLs for fabricating stable, efficient and reproducible planar PSCs.