A new tin-based-precursor solution for reproducible and high-quality SnO2 electron transporting layers in carbon-based perovskite solar cells

Used as an electron transporting layer (ETL), SnO2 is one of the most commonly used materials for perovskite solar cells (PSCs) due to its excellent semiconducting properties. However, the conventional precursor solution (SnCl2⋅H2O in ethanol) for SnO2 film deposition suffers from an ageing effect, which inhibits its use for PSCs production on an industrial scale. For the first time, a stable precursor solution based on tin (II) 2-ethylhexanoate (C16H30O4Sn) has been presented in this work for the preparation of reproducible and high-quality SnO2 ETLs.Our proposed route requires an annealing temperature of 180 °C, owing to the highest quality and the greater charge transfer at the ETL/perovskite interface. The PSCs prepared from our proposed route provided better photovoltaic performance compared to conventional ones. The effects of aged precursors (0–30 days) were also examined. It has been found that the PSCs with a SnO2 film deposited from the C16H30O4Sn precursor offered a negligible solution ageing effect and performed better than the PSCs with a SnO2 film deposited from the SnCl2 precursor. The main reason for this characteristic could be related to the quality of SnO2 films, which are influenced by the colloidal chemistry of the precursor solution. Lastly, our reproducible route is beneficial for preparing high-quality SnO2 films used in photovoltaic applications and other optoelectronic devices.