Abstract
Abstract Organic solar cells (OSCs) are emerging as promising candidates for space power generation due to their lightweight nature and rapidly advancing power conversion efficiencies. However, their resilience to the harsh space environment remains a critical factor for practical applications. This study investigates the impact of varying PM6:Y6 active layer thicknesses on the performance and radiation hardness of OSCs subjected to intense 170 keV short‐pulse (150 ns) proton irradiation, simulating operation in Low Earth Orbit, followed by thermal annealing. Proton irradiation induced significant changes in charge recombination and extraction dynamics, resulting in a performance degradation exceeding 50%. Notably, OSCs with thinner active layers demonstrate better radiation resistance and more effective recovery after annealing, attributed to reduced bulk trap concentrations and enhanced charge extraction efficiency. These findings provide valuable insights into the design and optimization of radiation‐hardened OSCs for space applications.