Control over MoSe2 formation with vacuum-assisted selenization of one-step electrodeposited Cu-In-Ga-Se precursor layers.

Cu(In,Ga)Se2 (CIGS) absorbers are prepared by direct current electrodeposition process followed by selenization of precursors. Selenization of electrodeposited layers is performed in a tubular furnace at 550 °C in elemental selenium atmosphere using Ar as carrier gas. The effect of evacuation of tube prior to the selenization on the formation of CIGS absorbers is studied. Characterization of CIGS absorbers reveals that the samples selenized without prior evacuation found to have excess MoSe2 formation at the CIGS/Mo interface leading to bulk cracks in underlying Mo back contact compared to their counterparts. Although the fabricated solar cells using the absorbers, prepared with and without evacuation, are observed to be photoactive, the cells from vacuum-based selenization showed improvement in performance compared to the cells from non-vacuum selenization. The process is further being improved to enhance the efficiency, which can pave way towards environmentally friendly low-cost solar cells.