Efficiency Enhancement of Copper Indium Gallium Diselenide‐Based Thin‐Film Solar Cell with Copper Iodide as Hole‐Transport Layer: A Simulation Approach

Herein, a new thin‐film solar cell (TFSC) structure utilizing copper indium gallium diselenide (CIGS) absorber is designed, and the performances of proposed device are evaluated by using the SCAPS‐1D simulator. This numerical result aligns closely with the reported experimental findings, providing the validity of this theoretical approach. This research investigates the introduction of CuI as hole‐transport layer (HTL) on performances of the suggested heterojunction TFSC comprising Al/FTO/CdS/CIGS/CuI/Ni. It is revealed that the proper band alignment at the CIGS/CuI interface enhances the device efficiency by minimizing the back surface carrier recombination loss. The photovoltaic performances of the proposed heterojunction TFSC are also examined by varying the thickness, carrier density, and defects of different layers, as well as operating temperatures and recombination velocity at the back contact. In this work, the cell structure is optimized at 0.8 μm for absorber and 0.2 μm for CuI HTL, respectively; on the other hand, the optimum doping concentrations of 10¹⁷ and 10¹⁸cm⁻³ for CIGS and CuI are found. An efficiency of 29.02% is obtained at the optimized thickness and carrier concentrations. Therefore, these findings imply that the nontoxic CuI can be passivated effectively at rear surface of the low‐cost CIGS TFSC.