A facile strategy to adjust SnO2/perovskite interfacial properties for high-efficiency perovskite solar cells

The interface between the electron transport layer (ETL) and the perovskite film plays a vital role in the performance of perovskite solar cells (PSCs). Here, (2-hydroxyethyl)amine hydroiodide (EOAI) is employed to regulate the interface properties at the SnO2/perovskite. The -NH3+ positive and I- negative ion groups in EOAI, which are anchored on the surface of SnO2 through -OH groups, can passivate the interface defects of perovskite films. Besides, the modified ETL has a smaller work function (WF) and E-VB than pristine ones, which contributes to efficient charge transport and collection. Furthermore, the introduction of EOAI can also improve the crystallinity of the perovskite layer. As a result, PSCs with EOAI-modified SnO2 produce a champion power conversion efficiency (PCE) of 22.61%, and an improved environmental stability. At the same time, the 1.68 eV wide-band gap perovskite solar cell achieved a PCE close to 20% and the semitransparent device also achieved an efficiency of over 17%.