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内容記述 |
Space solar cells supply power to spacecrafts to achieve their mission. Cu (In, Ga) (Se, S)2 (CIGS) solar cells are promising for the next-generation space solar cells because of their high radiation tolerance. The robustness of CIGS solar cells to radiation has been proven in the on-orbit demonstration test. These reports suggested that radiation defects of CIGS cells recovered by the thermal annealing and light irradiation in space. To predict the on-orbit radiation degradation of CIGS cells, it is necessary to understand this recovery property. However, it is difficult to assess the degradation and recovery separately, because the small activation energy (Ea) of CIGS could cause both phenomena simultaneously during radiation exposure. Hence, we focused on in-situ proton irradiation tests and I-V measurements in low temperature (−60℃) to suppress the self-healing effect and assess the pristine radiation degradation. The slope of temperature coefficient of Voc became steeper after proton irradiation. It suggests that a significant recovery did not occur from −60℃ to room temperature. Following that, we conducted heat-light soaking (HLS) treatment with AM0 light at various temperatures for CIGS cells and calculated the Ea to assess the recovery property. Furthermore, we also investigated the effect of operation voltage during HLS at the open circuit and max power point voltage to discuss the role of photocarrier recombination in defect healing. Our study will provide valuable insights to understand the self-healing mechanism of CIGS solar cells. |
