SnO2-based electron transporting layer materials for perovskite solar cells: A review of recent progress

Abstract In recent years, due to their high photo-to-electric power conversion efficiency (PCE) (up to 23% (certified)) and low cost, perovskite solar cells (PSCs) have attracted a great deal of attention in photovoltaics field. The high PCE can be attributed to the excellent physical properties of organic–inorganic hybrid perovskite materials, such as a long charge diffusion length and a high absorption coefficient in the visible range. There are different diffusion lengths of holes in electrons in a PSC device, and thus the electron transporting layer (ETL) plays a critical role in the performance of PSCs. An alternative for TiO 2 , to the most common ETL material is SnO 2 , which has similar physical properties to TiO 2 but with much higher electron mobility, which is beneficial for electron extraction. In addition, there are many facile methods to fabricate SnO 2 nanomaterials with low cost and low energy consumption. In this review paper, we focus on recent developments in SnO 2 as the ETL of PSCs. The fabrication methods of SnO 2 materials are briefly introduced. The influence of multiple SnO 2 types in the ETL on the performance of PSCs is then reviewed. Different methods for improving the PCE and long-term stability of PSCs based on SnO 2 ETL are also summarized. The review provides a systematic and comprehensive understanding of the influence of different SnO 2 ETL types on PSC performance and potentially motivates further development of PSCs with an extension to SnO 2 -based PSCs.