Metal Oxide CrO_x as a Promising Bilayer Electron Transport Material for Enhancing the Performance Stability of Planar Perovskite Solar Cells

Abstract

The stability of both the perovskite material and the interfacial layer is a key issue toward commercializing perovskite solar cells, due to the detrimental effects of water and oxygen under ambient conditions. Here, we report a solution‐processed organic–inorganic halide perovskite solar cell that employs a bilayer PC 61 BM/CrO x as the electron transport layer. Use of an additional CrO x interfacial layer can enhance the stability of a device in air without encapsulation by more than 10 times compared to that for a device using only a PC 61 BM electron transport layer. The device with a CrO x interfacial layer can also improve the power conversion efficiency by 17.5% compared to that using PC 61 BM only. The improved performance is attributed to the better matching of the energy levels of the active layer with the metal electrode and more effective electron collection when using interfacial CrO x as the bilayer electronic transport layer. It was also found that use of CrO x as a passivating layer could resist the diffusion of water and oxygen into the active layer and prevent the reaction of the metal electrode with the perovskite layer.