This study investigates the annihilation of intragrain impurities in perovskite solar cells (PSCs) using in situ scanning transmission electron microscopy (STEM) and computational modeling. Intragrain impurities, such as PbI₂ nano-clusters, can negatively affect the efficiency and stability of PSCs. However, these impurities can be healed by external energy stimuli, such as an electron beam, leading to the transformation of these impurities into perovskite phases. This process, termed intragrain impurity annihilation (IGIA), was observed to improve the optoelectronic properties and reduce intra-crystal strain in PSCs. The study also demonstrates that laser-induced IGIA can enhance the performance of PSCs, particularly in formamidinium-cesium (FA-Cs) perovskite solar cells. The IGIA process was found to be effective in both solution-processed and post-synthesis storage conditions. The study further shows that IGIA can be used to recover the performance of PSCs during storage. The findings suggest that IGIA can be a promising strategy for defects elimination and improving the power conversion efficiency (PCE) of PSCs. The study also highlights the importance of understanding the fundamental behaviors of intragrain defects and impurities in PSCs for device advancement. The results demonstrate that IGIA can be applied to various perovskite compositions, including MA-Cs and FA-Cs, and can significantly improve the stability and performance of PSCs. The study provides a new approach for solar cell advancement by translating atomic-level fundamental studies to module-level device technologies.This study investigates the annihilation of intragrain impurities in perovskite solar cells (PSCs) using in situ scanning transmission electron microscopy (STEM) and computational modeling. Intragrain impurities, such as PbI₂ nano-clusters, can negatively affect the efficiency and stability of PSCs. However, these impurities can be healed by external energy stimuli, such as an electron beam, leading to the transformation of these impurities into perovskite phases. This process, termed intragrain impurity annihilation (IGIA), was observed to improve the optoelectronic properties and reduce intra-crystal strain in PSCs. The study also demonstrates that laser-induced IGIA can enhance the performance of PSCs, particularly in formamidinium-cesium (FA-Cs) perovskite solar cells. The IGIA process was found to be effective in both solution-processed and post-synthesis storage conditions. The study further shows that IGIA can be used to recover the performance of PSCs during storage. The findings suggest that IGIA can be a promising strategy for defects elimination and improving the power conversion efficiency (PCE) of PSCs. The study also highlights the importance of understanding the fundamental behaviors of intragrain defects and impurities in PSCs for device advancement. The results demonstrate that IGIA can be applied to various perovskite compositions, including MA-Cs and FA-Cs, and can significantly improve the stability and performance of PSCs. The study provides a new approach for solar cell advancement by translating atomic-level fundamental studies to module-level device technologies.