Potential of advanced optical concepts in chalcopyrite-based solar cells

The potential of three advanced optical concepts in chalcopyrite-based solar cells is investigated by means of simulations with realistic optical and electrical parameters of state-of-the-art CGS and CIGS cells. First, a monolithically stacked tandem CGS/CIGS structure is analysed, achieving efficiencies up to 20.3% under standard test conditions. Then, in order to reduce the effects of the parasitic sub-bandgap absorption, a wavelength-selective intermediate reflector is incorporated in the tandem, leading to efficiencies up to 20.8%. Finally, the concept of spectrum splitting is tested in a hybrid four-terminal configuration of dislocated CGS and CIGS cells, and efficiencies up to 22.5% are simulated. To indicate further possible improvements, all three concepts are also tested in optically and electrically idealised CGS/CIGS structures, indicating the potential of efficiencies up to 28%.