Advanced Surface Passivation Enables High-Performance Carbon-Based All-Inorganic Perovskite Solar Cells

The all-inorganic perovskite CsPbI2Br has garnered significant attention due to its excellent thermal stability and suitable band gap. The use of carbon electrode materials can further enhance the thermal and moisture stability of the device and reduce the cost. However, the introduction of such materials causes an energy level mismatch and poor contact between the carbon electrode and perovskite, resulting in carrier recombination. In this study, we incorporated small molecule N-(4-Cyanophenyl)guanidine (NG) as a modifier to passivate trap density, to manage the energy level, and to improve interface contact. With the addition of NG, device efficiency increased from 10.24% to 12.89%. Moreover, the stability of the device was significantly improved. This study underscores the importance of modifiers and offers a concise strategy for enhancing the all-inorganic CsPbI2Br perovskite solar cells with respect to performance and stability.