Performing Relevant Irradiation Experiments: The Role of Proton Flux in the Dynamic Annealing during Irradiation of Cu(In,Ga)Se ₂ ‐Based Solar Cells

Laboratory irradiation tests are crucial to evaluate the viability of photovoltaic technologies for space applications. This work investigates the effect of the proton flux on the radiation hardness of Cu(In,Ga)Se 2 ‐based solar cells. Two solar cells were irradiated with 1 MeV protons at equal fluence (∼10 13 H + cm − 2 ) under distinct fluxes. The optical and electrical characterization revealed that the proton irradiation induces a higher density of defects, some deep in the bandgap, leading to the emergence of new recombination channels and the degradation of the device's performance. Besides the common degradation observed for both cells, the extent of damage shows a dependency on the irradiation flux. The cell irradiated with a lower proton flux exhibited greater degradation of its open‐circuit voltage, fill factor, power conversion efficiency, and a higher density of deep defects in the bandgap. On the other hand, the higher flux caused stronger losses both in external quantum efficiency and short‐circuit current, suggesting a different nature of the induced damage. Altogether, these findings point to a flux‐dependent balance between defect generation and dynamic annealing processes that occur during irradiation, highlighting the need to consider the irradiation flux as a critical parameter in radiation hardness studies of space‐aimed photovoltaic technologies.