A customized fullerene based metal oxide electron transport layer surface activity inhibitor to enhance the operational stability of perovskite solar cells

One of the most notorious problems with classic perovskite (MAPbI₃) is the rapid degradation induced by superoxide radicals (O₂˙⁻) generated on the surface under light and O₂ conditions (light/O₂). This work found that SnO₂ and TiO₂ surfaces can generate O₂˙⁻, inducing hidden degradation at the bottom of MAPbI₃ thin films, leading to a rapid decline in the performance of packaged devices. Using TiO₂ and SnO₂ as electron transport layers, we investigate the relationship between the number of O₂˙⁻ generated on their surfaces and the degradation rate of MAPbI₃ films. A fullerene idebenone derivative (C₆₀IDB) was introduced as a buffer layer between SnO₂ and MAPbI₃ to clear O₂˙⁻ and eliminate degradation, decrease the density of interface defect states, and accelerate the transmission of photogenerated electrons. Consequently, the C₆₀IDB-modified device had a maximum efficiency of 22.17%, among the most significant recorded efficiencies for MAPbI₃-based perovskite solar cells (PSCs). C₆₀IDB eliminates degradation at the MAPbI₃ films' buried interface, and following 528 hours of UV irradiation in ambient air, the target device maintained 93% of the original power conversion efficiency (PCE). This work reveals the veiled degradation at the buried interface of MAPbI₃ induced by O₂˙⁻ and provides reliable solutions.