MAPbI3-on-CuInSe2 two-terminal monolithically integrated and four-terminal mechanically stacked tandem solar cells: A Theoretical Investigation Using SCAPS-1D

Two-terminal (2-T) and four-terminal (4-T) tandem solar cells with wide bandgap perovskite (MAPbI3) as the top sub-cell and low bandgap copper indium diselenide (CuInSe2, CIS) as the bottom sub-cell have potential to outperform the single-junction power conversion efficiency. The proper consideration of native defects density and interface defects density in tandem solar cell (TSC) is required to achieve the full ability. The present paper examines a MAPbI3-on-CuInSe2 (MAPbI3-on-CIS) TSC. The bottom sub-cell of CIS has a bandgap of 1.04 eV, while the top sub-cell of MAPbI3 has a bandgap of 1.61 eV. The performance of the independent top and bottom sub-cells is explored by considering the physical parameters such as interface defects density, bulk defects density, and absorber layer thickness. The filtered spectra have been used to investigate the performance of 2-T monolithically integrated and 4-T mechanically stacked TSCs. When measuring the short-circuit current density (JSC) in a 2-T monolithic TSC, the top sub-cell's absorber layer thickness is changed to determine the exact thickness for the current matching condition. The proposed 2-T monolithic TSC satisfies the current matching requirement at a thickness of 0.346 μm of the top sub-cell's absorber layer, resulting in a power conversion efficiency (PCE) of 30.21%. The best simulated PCE of 4-T mechanically stacked TSC is 31.07%.