SiO2 and Al2O3/SiO2 coatings for increasing emissivity of Cu(In, Ga)Se2 thin-film solar cells for space applications

In this study, optical coatings were investigated as substitutes for the coverglass on flexible thin-film space solar cells. The inherent low emissivity of copper–indium–gallium–diselenide (CIGS) thin-film solar cells was increased using optical coatings for thermal balance in space. Evaporated silicon dioxide (SiO2) and an additional aluminum oxide (Al2O3) coating on the CIGS solar cell increased the emissivity from 0.18 to 0.77. Higher emissivity was realized with the Al2O3/SiO2 double-layer coating than with the SiO2 single-layer coating. The straightforward double-layer coating gives the CIGS solar cells appropriate radiative properties for keeping the cell within a permissible temperature range in space.