Study the effect of space radiation on ISO-type multijunction solar cells

Multijunction, GaInP/GaAs/Ge tandem solar cells have been extensively used in space as the power generation source for satellites due to their high conversion efficiency, high radiation tolerance and low-temperature coefficient. The most critical characteristic of space solar cells is the radiation hardness of the device. The space radiation environment degrades the long-term performance of the solar cell when they are exposed to the radiation. The effect of radiation on single-junction cell is well understood, established and well-studied. But the radiation effect on multijunction solar cell and its characterization needs to be studied in detail. The study is carried out on the effect of space radiation on ISO-type (sub-cells) cells of multijunction solar cells, its characterization and compared with the full cell and among three sub-cells which one is more susceptible to radiation. Different characterization techniques Dark IV, Light IV, Spectral Response and Electroluminescence are used to characterize sub-cells as well as full cell. The reverse saturation current, solar cell ideality factor, electrical parameters, current density, series and shunt resistance of sub-cells and full cells were estimated for pre and post-electron and proton radiation. This study helps in optimization of the solar cell design, material selection and manufacturing processes of multijunction solar cell. Also, the results of this study are useful in modeling of multijunction solar cell.