Dual Defense against Interface Defects and Environmental Stress via Synergistic Encapsulation for Efficient and Stable Perovskite Solar Cells

Due to their exceptional photovoltaic performance, perovskite solar cells (PSCs) have become attractive candidates for future photovoltaic technologies. However, the influence of interface defects and external environmental stress (thermal and moisture) constrains the long-term stability of the PSCs. Here, we propose an internal and external synergistic encapsulation strategy to enhance device stability. Internal encapsulation is achieved by depositing large-sized 3,4,5-trifluoroaniline hydroiodide (TFH) onto three-dimensional (3D) perovskite films. TFH passivates defects and significantly improves the heat resistance of perovskite films, preventing initial degradation of the perovskite film during the encapsulation process. On this basis, we employ an external encapsulation method involving low-temperature laminate sealing. The encapsulation layer effectively blocks moisture and oxygen, while low-temperature encapsulation avoids the degradation and damage of TFH itself, achieving a nondestructive physical barrier. Thus, the power conversion efficiency (PCE) of the TFH-modified PSCs increases from 24.32% to 26.03%. The PSCs maintain 92.2% of the initial PCE after 400 thermal cycles of 2400 h, demonstrating exceptional long-term stability. The collaborative encapsulation strategy offers novel prospects for enhancing the stability of PSCs with a high PCE.