Atomic layer deposition of SnO₂ using hydrogen peroxide improves the efficiency and stability of perovskite solar cells

Low-temperature processed SnO₂ is a promising electron transporting layer in perovskite solar cells (PSCs) due to its optoelectronic advantage. Atomic layer deposition (ALD) is suitable for forming a conformal SnO₂ layer on a high-haze substrate. However, oxygen vacancy formed by the conventional ALD process using H₂O might have a detrimental effect on the efficiency and stability of PSCs. Here, we report on the photovoltaic performance and stability of PSCs based on the ALD-SnO₂ layer with low oxygen vacancies fabricated via H₂O₂. Compared to the ALD-SnO₂ layer formed using H₂O vapors, the ALD-SnO₂ layer prepared via H₂O₂ shows better electron extraction due to a reduced oxygen vacancy associated with the highly oxidizing nature of H₂O₂. As a result, the power conversion efficiency (PCE) is enhanced from 21.42% for H₂O to 22.34% for H₂O₂ mainly due to an enhanced open-circuit voltage. Operational stability is simultaneously improved, where 89.3% of the initial PCE is maintained after 1000 h under an ambient condition for the H₂O₂-derived ALD SnO₂ as compared to the control device maintaining 72.5% of the initial PCE.