Fe 2 O 3 as an Electron Transport Material for Organo-Metal Halide Perovskite Solar Cells

Sputtered iron (III) oxide (Fe 2 O 3 ) was used as an electron transporting material for methylammonium lead iodide perovskite. The fill factor and efficiency of the solar cell improved as the layer thickness increased from 17 to 43 nm. The performance dropped when increasing the thickness to 67 nm due to parasitic absorption of the iron oxide. Open circuit voltage of the devices was 0.2-0.4 V below record efficiency cells, which is attributed to large work function of the iron oxide layer. However, a thin layer of PCBM between the Fe 2 O 3 and the perovskite layers improved the open circuit voltage. Introduction of dopants in the iron oxide layer may further result in improved device performance.