Design and performance investigation of CIGS/SWCNT tandem solar cell for efficiency improvement

This research work demonstrates the design and simulation of highly efficient tandem solar cell by using SCAPS-1D software. This tandem solar cell has been designed with a higher bandgap Copper Indium Gallium Diselenide (CIGS) absorber as a top cell and a lower bandgap Single Wall Carbon Nano Tube (SWCNT) absorber as a bottom cell, which are arranged in the series connection. Firstly, both top and bottom solar cells were analysed under standalone afterward, tandem configuration was developed with the top cell illumined by AM 1.5 spectrum and the bottom cell illumined by AM 1.5 filtered by top cell spectrum. The effects of absorber thickness, doping density, and bandgap on the output characteristics of the solar cell are also investigated. The current matching of both cells is attained by tuning the bandgap and thickness of Cu(In1-xGax)Se2 absorber of the upper cell. The remarkable efficiency of 38.91 % (Voc = 1.3441 V, Jsc = 37.87 mA/cm2 and FF = 76.41 %) is attained of the proposed CIGS/SWCNT tandem device at a thickness of 860 nm and 2000 nm for absorber of top and bottom cell respectively. The results of this research suggest a route for the fabrication of CIGS/SWCNT tandem solar cell with high efficiency.