Stable Inverted Perovskite Solar Cells with Efficiency over 23.0% via Dual-Layer SnO<sub>2</sub> on Perovskite
Fei Fei, Yunxiao Liao, Yibo Xu, Shubo Wang, Lvzhou Li, Xu Dong, Xiaoshuang Zhou, Jie Gao, Kaifeng Wang, Ningyi Yuan, Jianning Ding
Abstract
Perovskite solar cells (PSCs) have shown great potential for reducing costs and improving power conversion efficiency (PCE). One effective method to achieve the latter is to use an all-inorganic charge transport layer (ICTL). However, traditional methods for crystallizing inorganic layers often result in the formation of a powder instead of a continuous film. To address this issue, we designed a dual-layer inorganic electron transport layer (IETL). This dual-layer structure consists of a layer of SnO 2 nanocrystals (SnO 2 NCs) deposited via a solution process and a dense SnO 2 layer deposited through atomic layer deposition (ALD SnO 2 ) to fill the cracks and gaps between the SnO 2 NCs. PSCs having these dual-layer SnO 2 ETLs achieved a high efficiency of 23.0%. This efficiency surpasses the recorded performance of ICTLs deposited on the perovskite. Furthermore, the PCE is comparable to that achieved with a C60 ETL. Moreover, the high-density structure of the ALD SnO 2 layer inhibits the vertical migration of ions, resulting in improved thermal stability. After continuous heating at 85 °C in 10% humidity for 1000 h, the PCE of the dual-layer SnO 2 structure decreased by 18%, whereas that of the C60/BCP structure decreased by 36%. The integration of dual-layer SnO 2 into PSCs represents a significant advancement in achieving high-performance, commercially viable inverted monolithic PSCs or tandem solar cells.