Radiation-tolerant GaAs heterojunction solar cells

A major challenge for space solar cells is degradation caused by high-energy radiation. This study aims to mitigate radiation degradation in GaAs solar cells by employing a hetero p-n junction. Our first approach focuses on reducing the radiation damage coefficient for carrier lifetime in the depletion region ( K τ d e p ). We demonstrate, through simulations and experiments, that forming the depletion region within the wide-bandgap emitter effectively reduces K τ d e p . Second, we seek to enhance the internal luminescence efficiency in the neutral region by increasing the doping concentration of the narrow-bandgap base layer. Simulations and experiments reveal that a high base doping concentration suppresses non-radiative recombination losses in the neutral region caused by radiation-induced defects. As a result, a thin-film GaAs heterojunction solar cell incorporating these two strategies achieves a maximum power point remaining factor of more than 99% after irradiation with 1 MeV electrons at a fluence of 1×10 14 cm −2 .