Performance enhancement by introducing different chlorinated salts in the SnO2 electron transfer layer of perovskite solar cells

Tin oxide (SnO2) is one of the important and commonly used electron transfer layers (ETLs) in the planar structure of perovskite solar cells (PSCs). Doping the SnO2 layer with chlorinated salts such as potassium chloride (KCl) has been reported to improve the power conversion efficiency (PCE), intriguing further exploration of other chlorinated salts. Herein, the results from various chlorinated salts in addition to KCl are evaluated. It was observed, that though the PSCs with KCl doped SnO2 layer yield the best PCE (~17%), the ETL layer doped with other chlorinated salts such as sodium chloride (NaCl) and Iron chloride (FeCl3) also showed improvement in performance from the pristine SnO2 (~15 %). Moreover, the results from the SnO2-NaCl-based devices are found to be comparable to the SnO2-KCl. Performance enhancement is attributed to the passivation of defects in the interface and reduction in the non-radiative recombination losses. The established trend is supported by the current-voltage (J-V) and photoluminescence (PL) studies.