On the Viability of CIGS Technology for Silicon Based Tandem Solar Cells

This work models the efficiency obtainable from tandem structures with a silicon bottom cell and a CIGS top cell. Its results are based on the characteristics obtained by different authors on single CIGS solar cells, modelling their dependence of Voc on EG and the dependence of Voc on recombination mechanisms with kT or 2kT dependence. Results are modelled for different connection strategies: 4 terminals, with independent bias conditions for top and bottom cells; 3 terminals, with a parallel interconnection of both sub-cells (one top in parallel with a series of two bottoms); 2 terminals as conventional tandem cells with series connection. The work shows the viability of CIGS / Silicon tandem cells for any configuration with different band gap targets for optimum conversion efficiency, upgrading the efficiency of a single high efficiency silicon solar cell.