摘要：SummaryThe highest theoretical efficiency of double junction solar cells is predicted for architectures with the bottom cell bandgap (Eg) of approximately 0.9–1.0 eV, which is lower than that of a typical Si cell (1.1 eV). Cu(In,Ga)(Se,S)2(CIGS) solar cells exhibit a tunableEgdepending on their elemental composition and depth profile. In this study, various CIGS solar cells withEgranging from 1.02 to 1.14 eV are prepared and a spectrum splitting system is used to experimentally demonstrate the effect of using lower-Egcells as the bottom cell of two-junction solar cells. The four-terminal tandem cell configuration fabricated using a mixed-halide perovskite top cell (Eg = 1.59 eV; stand-alone efficiency = 21.0%) and CIGS bottom cell (Eg = 1.02 eV; stand-alone efficiency = 21.5%) with a 775-nm spectral splitting mirror exhibits an efficiency of 28.0% at the aperture area of 1 cm2.Graphical AbstractDisplay OmittedHighlights•CIGS bottom solar cells withEgranging from 1.02 to 1.14 eV are prepared•The lower theEgof CIGS bottom cell, the higher PCE of PVK/CIGS tandem solar cell•PCE of 28% was demonstrated in a 1 cm2-sized PVK/CIGS 4-Terminal solar cell•The result can be utilized to design better tandem solar cell in the futureInorganic Materials; Optical Materials; Materials Science; Materials Application; Energy Materials
