Proton irradiation effects on NiO/ZnO visible-light-transparent solar cells for space applications

In this study, the feasibility of in-space applications of a NiO/ZnO visible-light-transparent solar cell was investigated. The current density-voltage and external quantum efficiency measurements were conducted under air mass (AM) 0 conditions, and a short-circuit current density under AM 0 increased 2.6 times compared to that under AM 1.5. This significant increase is attributed to the absorption of only ultraviolet light with a wavelength of less than 400 nm, the irradiance of which is especially large in AM 0. Moreover, the degradation of photovoltaic properties of NiO/ZnO solar cells after 380 keV proton irradiation was evaluated to determine the possibility of long-term operation in space. No significant degradation was observed at a proton fluence of less than 3 × 1014 cm-2- 1 × 1015 cm-2. The NiO/ZnO solar cells showed the potential of a higher radiation tolerance under proton irradiation, as compared to Cu(In,Ga)Se2 (CIGS) or GaAs-based solar cells.