Multifunctional Ionic Liquid as an Interfacial Modifier for High-Performance and Stable NiOx-Based Inverted Perovskite Solar Cells

Interface instability has evolved into the primary aspect that limits the durability improvement of perovskite solar cells (PSCs). Interface modification with suitable molecules is widely considered an effective path for improving the interface state. Herein, an ionic liquid modified layer, 1-ethyl-3-methylimidazolium aminoacetate (EMIMAE), is brought to modify NiO_x/perovskite interface. The EMIMAE layer can interact with the adjacent layer to regulate the perovskite growth, passivate defects in the film, and promote charge transport in PSCs. Eventually, the optimized device's efficiency rises to 18.6%, which is a substantial improvement over the control device. Particularly, after 1000 h of continuous maximum power point tracking, the device can still retain 95% of its initial efficiency. This work proposes a simple idea to ameliorate the device interface and boost the commercialization of NiO_x based devices.