Cu(In,Ga)Se2 absorbers from stacked nanoparticle precursor layers

The following paper presents a processing route for Cu(In,Ga)Se2 absorber layers that is based on nanoparticle dispersions which are applied by doctor blade deposition and converted with elemental selenium vapors. In particular, the preparation of the precursor layers is investigated by systematically assessing the influence of the stacking sequence of mono- and multi-metallic layers on sintering, elemental distribution and solar cell efficiency. By applying suitable stacking sequences, precursor layers with both local Cu-rich and over-all Cu-poor stoichiometry could be prepared that allowed improved sintering properties and modifications of the gallium gradient. Despite the still prevailing porosity of the absorber layer, solar cells with efficiencies exceeding 5% could be obtained.

► Description of a nanoparticle based non-vacuum deposition route for CIGS absorbers
► The process omits the use of toxic and explosive H2, H2S, and/or H2Se gases.
► Stacked precursor layers with improved grain growth and Ga double-gradient
► Up to 5.8% efficient cells have been produced by this process.