Rational tuning of SnO2 electron transport layer grown by atomic layer deposition for performance improvement of perovskite solar cells.

[Display omitted] • Atomic-level precision SnO 2 thin films were grown by a pulsed laser deposition (ALD) method. • The ALD conditions were fine-tuned to examine their effects on film properties. • The carrier concentration and Fermi level tended to increase with increasing the growth temperature, while the surface roughness and oxygen content showed the reverse trend. • PSCs with SnO 2 ETLs grown at various ALD conditions were fabricated and tested. • A PSC with a 15 nm-thick SnO 2 ETL grown at 200 °C showed the best cell performance. The electron transport layer (ETL) of a perovskite solar cell (PSC) plays a pivotal role in determining cell performance. In this work, an atomic layer deposition (ALD) technique was employed to grow high-quality SnO 2 thin films, and those ALD-grown SnO 2 films were used as ETLs of PSCs. The properties of films and the performance of PSCs were closely examined depending on the SnO 2 growth conditions. The SnO 2 films grown at higher temperatures showed a very small surface roughness (≤0.6 nm) though grown faster. The relative oxygen content of the film was inclined to decrease with increasing the growth temperature. Consequently, the carrier concentration and the Fermi level of the film became higher at elevated temperatures. PSCs with ALD-grown SnO 2 ETLs also revealed a clear correlation between cell performance and the film growth temperature. The results of this work may offer practical guidelines for enhancing the performace of a PSC that employs a metal oxide as an ETL. [ABSTRACT FROM AUTHOR]