We investigate the degradation of ZnO/CdS/ Cu(In, Ga)Sez heterojunction sol
ar cells for space applications and the defect generation in polycrystallin
e Cu(In, Ga)Se-2 thin films irradiation with 1-MeV electrons with fluences
phi(e) up to phi(e) = 5 x 10(18) cm(-2). Notable degradation of the solar c
ell performance starts at fluences of phi(e) = 10(17) cm(-2) where the open
circuit voltage decreases by about 5% while short circuit current and fill
factor remain essentially unaffected. Thus, Cu(In, Ga)Se-2 solar cells wit
hstand electron fluences which are higher by one order of magnitude or more
when compared to other technologies. A model describes the absolute open c
ircuit voltage loss considering the increase of space charge recombination
by electron irradiation-induced defects. Defect analysis by admittance spec
troscopy shows that acceptor defects with an energy distance of approximate
ly 300 meV from the valence band are generated at. a rate gamma = 0.017 (+/
-0.01) cm(-1).