High Bending Durability of Efficient Flexible Perovskite Solar Cells Using Metal Oxide Electron Transport Layer

With a rapid progress in photovoltaic performance over the past several years, organic–inorganic perovskite solar cells (PSCs) have been regarded as a promising candidate for next-generation photovoltaic devices such as lightweight and flexible photovoltaic equipment and portable systems. However, the photovoltaic performance and its durability during the mechanical bending test of flexible PSCs (fPSCs) are insufficient for the realistic application. This inadequacy stems from a lack of a superior electron transport material (ETM) for fPSCs. Here, we describe the application of SnO 2 as an ETM for fPSCs (SnO 2 -fPSCs), achieving outstanding photovoltaic performance and excellent mechanical bending durability. We demonstrate the high power conversion efficiency (PCE) of 17.1 and 16.2% with negligible hysteresis and the high stabilized power output of 17.0 and 15.9% of normal-architecture SnO 2 -fPSCs with a photoactive area of 0.1 and 1.0 cm 2, respectively. Moreover, the SnO 2 -fPSCs exhibit an excellent bending durability that retains 76.5% of the initial PCE even after 2000 times harsh bending cycle with a small bending radius of 4.0 mm on 0.1 cm 2 active area.