A facile room temperature solution synthesis of SnO2 quantum dots for perovskite solar cells

Abstract

The electron transport layer (ETL) is a critical component in planar single junction or tandem perovskite solar cells (PSCs), dominating the separation and electron extraction of charge carriers. Herein, we introduce a facile route to synthesize a SnO₂ quantum dot (QD) colloidal solution at room temperature using an alcohol-based solvent with the additive of deionized-water. A superior homogeneous ETL is obtained by spin coating of the QD colloidal solution with post-deposition annealing. Compared to the ETL prepared with the SnCl₂·2H₂O anhydrous alcohol solution, the champion power conversion efficiency of PSCs deposited on the SnO₂ QD based ETL is raised to 20.1% from 16.5%. The better performance is attributed to the excellent optical and electronic properties of the SnO₂ QD based ETL. Experimental analyses reveal that the SnO₂ QD based ETL enhances electron extraction and suppresses charge recombination, leading to improvement of solar cell performance. The appropriate concentration of the SnO₂ QD based solution is explored and the appropriate ratio of anhydrous alcohol to deionized water of the SnO₂ colloidal solution is obtained. Our results show the great potential of low temperature synthesized SnO₂ QD films for application as ETLs or interconnecting buffer layers for future highly efficient and reproducible low-temperature processed tandem PSCs.