Optimizing the design of CIGS-based solar cells: a computational approach

It was found that the efficiency η depends both on the gallium content, x, and the thickness of the absorber layers. For bi-layer cells, it is also a function of the relative thicknesses of the layers. η, for single layered cells, was found to depend both on the absorber layer thickness and the gallium content, x. As the thickness was increased (x = constant), η increased from ∼16% (1 μm thick absorber layer) to ∼20% (for 5 μm thick absorber layer). Any change of η was minimal for absorber layers containing between 20 and 60% gallium. For bi-layers η dropped sharply when a thin layer of CGS was added as a top layer. η then increased steadily until the CGS thickness was about 90% of the total thickness.