纯SnO₂与金属氯化物处理的SnO₂电子传输层对空气环境中制备的钙钛矿太阳能电池的影响：电学、光学和光伏特性

The low-temperature colloidal solution-processed tin oxide (SnO 2 )-based electron transport layer (ETL) has received considerable attention in the development of planar perovskite solar cells (PSC) to resolve issues encountered with conventional ETL, TiO 2 , e.g., effect of elevated temperatures processing, low mobility, and low UV photocatalytic activity. However, the presence of Sn vacancies and hydroxyl groups at SnO 2 surface hinders the PSC power conversion efficiency (PCE) and subsequently the long-term stability of PSC. In this study, the effect of pristine SnO 2 and KCl-treated SnO 2 ETL layers were studied for air ambient fabricated PSCs. From the W–H plot, the strain ( ε ) values were found to be 0.66 × 10 –3 ± 0.00026 and 0.87 × 10 –3 ± 0.00022 for the perovskite film on pure and KCl-treated SnO 2 , respectively. Solar cell devices on KCl-treated SnO 2 ETL showed a comparatively less diode quality factor ( n D2 = 1.55) and smaller reverse saturation current ( J o = 5.57 × 10 –5 mA/cm 2 ) as compared to pristine SnO 2 -based devices, suggesting reduced trap state density and suppressed non-radiative recombination. These findings are also complemented by steady-state photoluminescence. Further, the best solar cell device based on KCl-treated SnO 2 ETL shows improved J sc of 20.83 mA cm −2 , a FF of 70.61%, and a PCE of 15.3% than the cell based on pristine SnO 2 ETL, J sc of 19.28 mA cm −2 , FF of 54.16%, and PCE of 10.8%. The film composition is roughly assumed to be according to the fractions of the precursor solutions, i.e., FAI (1 M), PbI 2 (1.1 M), MABr (0.2 M), PbBr 2 (0.2 M), and CsI (1.5 M) in a DMF:DMSO solvent mixture. Further elemental analysis, for example by SIMS, will provide accurate compositions.