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

Abstract

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.