Highly efficient and stable perovskite solar cells via bilateral passivation layers

NiOx-based perovskite solar cells (PSCs) have drawn tremendous attention and achieved significant improvement in recent years. Interfacial engineering is a promising route for enhancing performances of PSCs with larger open-circuit voltage (V-OC) and short-circuit current density (J(SC)). Herein, we report a simple method for improving the performance of PSCs by applying bilateral polystyrene layers between the perovskite absorber and charge transport layers, respectively. The top and bottom surfaces of the perovskite layer are passivated and protected by ultrathin bilateral polystyrene layers, which results in highly efficient devices with a larger perovskite grain size, fewer interfacial defects and suppressed charge recombination. As a result, a power conversion efficiency (PCE) of 19.99% is achieved without hysteresis and the V-OC is as high as 1.149 V, which is so far the best result for p-i-n PSCs based on pure CH3NH3PbI3. Moreover, the devices also show improved long-term stability. This study provides a powerful strategy to design and prepare highly efficient and stable perovskite solar cells.