Solution-processed amino acid modified SnO2 electron transport layer for carbon-based CsPbIBr2 perovskite solar cells

• DOI: 10.1016/j.mssp.2021.105964
• Publication Date: 2021-05-30T16:13:10Z
• Authors: Siqi Han; Haiming Zhang; Yujie Li; Rufeng Wang; Qingchen He
• Keywords: Alanine

Abstract SnO2 has gathered wide attention as an electron transport layer (ETL) in perovskite solar cells (PSCs) for its outstanding properties such as low-temperature process, high mobility, and matched energy level. However, the low-temperature annealing of SnO2 may lead to the formation of large quantities of oxygen vacanices, which can give rise to nonradiative recombination. Herein, we introduce an alanine (C3H7NO2) with a high fusion point to modify the quality of SnO2 film in solution processing at a low temperature. The carboxylic acid group of alanine can crosslink to SnO2 via a chelating interaction, leading to the decreasing in traps and increasing in carrier transmission. Furthermore, the amino group of alanine could also promote the crystallization and suppress ion migration of the perovskite film through hydrogen bonds. The result demonstrates that using the C3H7NO2 modified SnO2 ETL with the optimal concentration, the highest power conversion efficiency (PCE) of carbon-based CsPbIBr2 PSC was obviously improved from 5.09% to 6.80%, leading to an increase by almost 33.60% compared to the PSC with pristine SnO2. More importantly, the PSCs with modified SnO2 had better long-term stability. This paper demonstrates the utility of the alanine modification approach boosting the performance of carbon-based PSCs.