Proton Degradation-free Flexible Chalcopyrite Solar Cells without Cover Glass and Adhesive

Strong radiation hardness against low-energy and high- energy proton irradiation on newly developed flexible chalcopyrite Cu(In, Ga)(Se, S)(2) solar cells without cover glass and adhesive was confirmed. Degradation of efficiency after 300 keV and 3 MeV proton irradiation (fluence varied from 10(11) to 10(13) cm(-2)) was fully recovered by heat light soaking. Capacitance-voltage measurement indicated recovery of the net carrier concentration after the heat light soaking. Compositional depth profile measurement suggested the full-recovery characteristics should be delivered from Ga-less and Cu-poor composition in the depletion layer in Cu(In, Ga)(Se, S)(2) absorber layer. We believe these results are one of big steps for achieving light-weight and low-cost space solar cells with long lifetime.