Effect of cesium fluoride treatment in bifacial Cu(In1-x,Ga-x)Se-2 solar cell

Bifacial Cu(In1-x,Ga-x)Se-2 (CIGS) thin film solar cells were fabricated on titanium-doped indium oxide (ITiO) coated soda-lime glass substrate, and the effect of cesium fluoride (CsF) treatment on solar cell performance was investigated. CsF treatment improved the photovoltaic properties of CIGS/ITiO-based solar cells not only under front-side illumination but also under rear-side illumination. The quantum efficiency for rear-side illumination improved significantly in CsF-treated CIGS solar cells. As a result, the bifaciality improved in the CsF-treated CIGS solar cell. ITiO exhibited good contact with the CIGS thin film, regardless of Cs incorporation. In addition, the effect of heat-light soaking treatment was also investigated in CIGS/ITiO-based solar cells.