Exploring potential of lead-free KSn0.5Ge0.5I3 based perovskite solar cell: A combined first-principle DFT and SCAPS-1D study

Abstract

Perovskite solar cells present a promising alternative to conventional silicon or lead-based solar cells, offering a synergistic blend of cost-effectiveness and potential for elevated power conversion efficiency. We investigated the potential of an innovative KSn0.5Ge0.5I3-based perovskite solar cell (PSC) using density functional theory (DFT) and SCAPS-1D simulation studies. Computational analysis via DFT probed the crystal structure, elastic, mechanical, and optoelectronic properties of KSn0.5Ge0.5I3. Tolerance factor computation (0.94) and negative formation energy (-3.16 eV) affirmed the thermodynamic stability of the orthorhombic phase in KSn0.5Ge0.5I3. Optical variables including refractive index, absorption coefficient, dielectric function, optical loss, and reflectivity, were computed to explore KSn0.5Ge0.5I3 viability in PV applications. Band structure analysis, density of states (DOS), and projected density of states (PDOS) have been used to determine the band gap (∼1.87 eV), effective masses, and mobility of e-/h+. We have conducted SCAPS-1D simulation for diverse PSCs configurations using various holes transport layers (HTLs) and electron transport layers (ETLs), identified IGZO (Eg = 3.05 eV) as a proficient ETL while CuSbS2 (Eg = 1.58 eV) as an effective HTL. A comprehensive investigation of parameters such as absorber layer thickness, shunt and series resistance, donor and acceptor density, absorber defect density, back contact metal, temperature, and interface characteristics was undertaken, and the impact on PV device performances was assessed through current-voltage (IV) and quantum efficiency (Q.E) characteristics curves. These findings underscore the potential of KSn0.5Ge0.5I3 as a promising material for PSCs, offering a sustainable and eco-friendly avenue for future renewable energy.