CIGS solar cells with very thin absorber layers

An additional carbon layer between Cu(In,Ga)Se₂ (CIGS) layer and molybdenum (Mo) back contact can increase the efficiency of solar cells with very thin absorber layers. In this study the so produced solar cells co-evaporated on top of a carbon layer are compared with cells co-evaporated directly on molybdenum. We found that the carbon layer leads to higher maximum current densities and higher maximum open-circuit voltages and thus higher maximum efficiencies (6.0% with carbon layer compared to 5.6% without for 250 nm CIGS thickness).