Computational analysis of LiMgI3: a promising material for solar energy conversion†

Abstract

This work employs density functional theory (DFT) using CASTEP to investigate the structural, electronic, and optical properties of cubic LiMgI₃ as an absorber material. The lattice parameters we examined match quite well with earlier theoretical results, and the phonon dispersion confirmed its dynamic stability. The electronic band structure and density of states (DOS) revealed that LiMgI₃ is a semiconductor, with band gaps of 1.162 eV using the GGA method and 1.922 eV using the HSE06 hybrid functional. Optical properties were evaluated within the photon energy range of 0–14 eV, key optical characteristics-such as absorption coefficient, reflectivity, refractive index, dielectric response, optical conductivity, and energy loss, all indicating excellent light-harvesting potential. To assess its device applicability, SCAPS-1D simulation software was used to model various solar cell architectures with LiMgI₃ as the absorber. A total of 60 configurations combining different electron transport layers (ETLs) such as WS₂, IGZO, TiO₂, ZnO, ZnS, and PCBM, and hole transport layers (HTLs) like Cu₂O, CuO, CBTS, CuI, P3HT, PEDOT:PSS, CuSCN, Spiro-OMeTAD, PTAA, and CdTe were evaluated. The ITO/WS₂/LiMgI₃/Cu₂O/Ni structure yielded the best performance, with a power conversion efficiency (PCE) of 20.73%, open circuit voltage (V_OC) of 1.495 V, a short circuit current (J_SC) of 15.78 mA cm⁻², and fill factor (FF) of 87.81%. This study analyzes how absorber and electron transport layer (ETL) thickness affect key photovoltaic parameters. It also examines the valence band offset (VBO) and conduction band offset (CBO) characteristics of different ETLs. The study further investigates the impact of series and shunt resistances, temperature, quantum efficiency (QE), capacitance–voltage (C–V) Characteristics, generation–recombination response, current density–voltage (J–V) characteristics, and impedance spectra on improving device performance. The exceptional photon capture efficiency of LiMgI₃ perovskite solar cells (PVSKs) holds significant potential for advancing photovoltaic and optoelectronic device technologies.