Enhancing the performance of the perovskite solar cells by modifying the SnO2 electron transport layer

The tin oxide (SnO2) electron transport layer (ETL) plays a vital role in the photo-conversion efficiency (PCE) and stability of organic-inorganic perovskite solar cells (PSCs). However, SnO2 ETL-induced defects such as hydroxyl groups, oxygen vacancies, exposed Sn atoms, and dangling bonds hinder device performance. In this study, rubidium chloride (RbCl) has been used to modify the SnO2 ETL. Perovskite film formed on the RbCl-modified SnO2 ETL exhibits improved crystallinity with enlarged grain size and reduced grain boundaries and enhanced optical absorption. The Hall-effect measurements indicate the improved carrier mobility, and the dark J-V curve shows the increment of electrical conductivity for the RbCl-modified SnO2 ETL. X-ray photoelectron spectroscopy (XPS) results demonstrate the surface defects passivation of the perovskite layer by modifying the SnO2 ETL. A champion PCE of 19.35% has been achieved for the RbCl-modified SnO2 ETL-based devices with improved stability, while the control devices with unmodified SnO2ETL show a PCE of 17.18%.