Radiation resistance of Cu(In,Ga)Se-2 solar cells under 1-MeV electron irradiation

Polycrystalline ZnO/CdS/Cu(In,Ga)Se-2 heterojunction solar cells display a very high radiation resistance under 1-MeV electrons. We irradiated high-ef ficiency Cu(In,Ga)Se-2 solar cells with 1-MeV electron fluences up to phi ( e) = 5 X 10(18) cm(-2). The loss in the conversion efficiency, starting at phi (e) = 10(17) cm(-2), was caused by the open circuit voltage loss. An an alytical model for the open circuit voltage describes the loss by consideri ng the increase in space charge recombination via deep defects introduced b y electron irradiation. A reduction of the doping density in the Cu(In,Ga)S e, absorber layer upon irradiation was analyzed by capacitance voltage meas urements. The rate at which the net doping density decreased was 0.045 cm(- 1). Accumulative irradiation shows that partial recovery of the radiation i nduced damage occurred during our analysis cycle well below 100 degreesC. ( C) 2001 Elsevier Science B.V. All rights reserved.