A study published in Nature (DOI: 10.1038/s41467-024-44974-0) investigates the impact of repeated thermal evaporation of C60 on the performance of perovskite-based solar cells. The research reveals that commercial C60 source materials, when repeatedly evaporated, can coalesce, leading to the formation of deep states within the perovskite bandgap and a systematic decrease in solar cell performance. This degradation is attributed to oxygen present in the initial source powder. However, further purification of C60 through sublimation to 99.95% purity before evaporation prevents coalescence, resulting in fully reproducible solar cell performances after repeated processing. The study also demonstrates that sublimed C60 maintains consistent performance in perovskite/silicon tandem solar cells, with open-circuit voltages and fill factors remaining stable over eight repeated processes. One of these cells achieved a certified power conversion efficiency of 30.9%. The findings highlight the importance of purifying C60 to ensure the scalability and efficiency of perovskite photovoltaic technologies. The research provides insights into the structural and electronic changes in C60 during thermal cycling, showing that sublimation enhances the quality of C60 films, reduces defect states, and improves electron mobility. The study also confirms that sublimed C60 can be used in industrial processes without performance loss, making it a promising solution for the commercialization of perovskite-based solar cells.A study published in Nature (DOI: 10.1038/s41467-024-44974-0) investigates the impact of repeated thermal evaporation of C60 on the performance of perovskite-based solar cells. The research reveals that commercial C60 source materials, when repeatedly evaporated, can coalesce, leading to the formation of deep states within the perovskite bandgap and a systematic decrease in solar cell performance. This degradation is attributed to oxygen present in the initial source powder. However, further purification of C60 through sublimation to 99.95% purity before evaporation prevents coalescence, resulting in fully reproducible solar cell performances after repeated processing. The study also demonstrates that sublimed C60 maintains consistent performance in perovskite/silicon tandem solar cells, with open-circuit voltages and fill factors remaining stable over eight repeated processes. One of these cells achieved a certified power conversion efficiency of 30.9%. The findings highlight the importance of purifying C60 to ensure the scalability and efficiency of perovskite photovoltaic technologies. The research provides insights into the structural and electronic changes in C60 during thermal cycling, showing that sublimation enhances the quality of C60 films, reduces defect states, and improves electron mobility. The study also confirms that sublimed C60 can be used in industrial processes without performance loss, making it a promising solution for the commercialization of perovskite-based solar cells.