Light Stability of Laser‐Assisted Glass Encapsulated Perovskite Solar Cells under Different Atmospheres

ABSTRACT The long‐term stability of perovskite solar cells (PSCs) is crucial for their commercial viability. This study investigates the influence of a controlled internal atmosphere within glass‐glass encapsulated devices on operational stability under illumination. Devices encapsulated under nitrogen (N 2 ) and carbon dioxide (CO 2 ) were compared with counterparts sealed in ambient air, which had uncontrolled moisture and oxygen levels. The study focused on dual cation (5‐AVA) 0.05 MA 0.95 PbI 3 perovskite films deposited on mesoporous TiO 2 , as well as hole‐transport material (HTM)‐free PSCs employing carbon electrodes. After more than 2000 h of exposure to 1 sun illumination at 45°C, films encapsulated in air exhibited significant morphological and compositional degradation. In contrast, devices encapsulated under N 2 and under CO 2 environments show markedly reduced degradation. After 1000 h of light exposure, the champion HTM‐free PSC sealed in ambient air exhibits a 25% decline in power conversion efficiency (PCE), whereas the devices sealed in CO 2 and N 2 display superior stability, with PCE reductions of approximately 12%. This work provides the first experimental demonstration that hermetic laser‐assisted glass frit encapsulation in moisture‐ and oxygen‐free environments effectively mitigates extrinsic degradation. It significantly improves the long‐term stability of (5‐AVA) 0.05 MA 0.95 PbI 3 films and carbon‐based HTM‐free PSCs under extended light soaking conditions (1 sun).