Gamma-Fe2o3 As A Novel Electron Transporting Material For Planar Heterojunction Perovskite Solar Cells By Simple Room-Temperature Solution Method

alpha-Fe2O3 has been demonstrated to be a promising electron transporting material (ETL) for fabricating efficient perovskite solar cells (PSCs) with good stability under ultraviolet light compared to the commonly used TiO2. However, alpha-Fe2O3 films need to be processed over 500 degrees C, which is a serious impediment to fabricate devices on the flexible substrates. Herein, gamma-Fe2O3, which could be deposited onto the substrates under room temperature, would be an alternative magnetic ETL with a reasonable performance. We report that pure and fine nano-sized gamma-Fe2O3 particles can be synthesized below 200 degrees C and the corresponding compact layers have been fabricated by a simple room-temperature solution process. The methylammonium lead iodide (MAPbI(3)) PSCs based on gamma-Fe2O3 show a power conversion efficiency of 12.86% with a short circuit current (J(sc)) of 21.79 mA/cm(2), an open circuit photovoltage (V-oc) of 0.93 V and a fill factor (FF) of 63.3%. These results indicate a possible direction for preparing flexible perovskite solar cells.