Probing the Interfacial Properties of ACIGS Solar Cells with Targeted Proton Irradiation

ACIGS solar cells are exposed to targeted radiation to probe the front and back interfaces of the absorber to assess the impact of space environments on these systems. These data suggest ACIGS cells are more radiation-hard than early CIGS devices likely due to the lower defect densities and more ideal interfaces in the ACIGS system. A combination of J–V and external quantum efficiency measurements indicates some improvement in the performance of the device due to the effects of local heating in the dominant ionizing electronic energy loss regime of proton irradiation that anneal the upper CdS/ACIGS interface. However, nonionizing energy losses at the base of the solar cell also appear to inhibit minority carrier collection from the back of the cell at the ACIGS/Mo interface, which is discussed in terms of defect-mediated changes in the doping profile, the Ga/Ga+In ratio, and impurity composition after proton irradiation.