Magnesium Acetate Key Enhancers for Electron Transport Layers in Highly Efficient and Stable Perovskite Solar Cells

The intrinsic characteristics of electron transport layers (ETLs) significantly influence the efficiency of conventional perovskite solar cell (PSC). This work introduces an in situ defect passivation approach utilizing magnesium acetate (MgAc) to mitigate bulk defects within SnO2 films. The incorporation of MgAc during SnO2 growth significantly reduces vacancy defects, including oxygen and tin vacancies, leading to enhanced electronic properties, such as improved conductivity and electron mobility. The morphological analysis reveals that MgAc-modified SnO2 (MgAc-SnO2) films exhibit a smooth surface with better crystallinity, which promotes uniform perovskite deposition and high crystallization quality. These improvements result in enhanced charge transport and reduced nonradiative recombination, achieving an efficiency of 25.35% for the device with MgAc-SnO2, surpassing the efficiency of 23.93% for the device with pristine SnO2. The unencapsulated devices with MgAc-SnO2 maintain 87.88%, 95.49%, and 84.51% of the initial efficiency upon heating at 85 °C for 1000 h, storing in the air for 1200 h, and continuously irradiating for 1000 h, respectively. The excellent stability is due to the reduction in defects of SnO2 bulk films and relaxed residual stresses of the perovskite to suppress degradation. The study highlights that MgAc modification serves as an effective approach to enhancing the efficiency and stability of PSCs, thereby advancing their commercial viability.