A novel investigation into strain-induced changes in the physical properties and solar cell performances of lead-free Ca3NCl3 perovskite

Abstract

The first-principle calculations were employed to analyze the structural, thermodynamic, electronic, optical, and mechanical properties of calcium-based halide perovskites, Ca3NCl3, under pressure variations from +6 % to −6%. The Ca3NCl3 materials are thermodynamically and dynamically stable, as indicated by the negative final enthalpy values obtained under pressures ranging from −6% to +6 %. The charge density maps confirm the existence of both ionic and covalent bonding features. The unstressed Ca3NCl3 has a direct bandgap of 1.66 eV with PBE functions, 2.32 eV with HSE functions and 1.48 eV with spin-orbit coupling (SOC) at the Γ point. When subjected to compressive strain, the bandgap reduces to 1.37 eV(PBE), 1.93 eV(HSE) and 1.08 eV(SOC) at −6% strain, causing a redshift in absorption coefficient peaks. Conversely, under tensile strain, the bandgap slightly rises to 1.92 eV(PBE), 2.60 eV(HSE) and 1.73 eV(SOC) at +6 % strain, resulting in a blueshift in absorption coefficient peaks. The Ca3NCl3 materials show enhanced optical absorption, loss function, conductivity, dielectric function, refractive index and reflectivity under applied pressure, making them more appropriate for use in solar absorbers, surgical tools, and optoelectronic devices. The investigation of the mechanical properties reveals that the Ca3NCl3 perovskite is mechanically stable. Moreover, with rising pressure (tensile to compressive), elastic constants, elastic moduli, ductility, machinability index, bulk modulus, shear modulus, pugh's ratio, young modulus and anisotropy all rise. The photovoltaic (PV) performance of novel cell configurations, featuring Ca3NCl3 as an absorber and CdS as an Electron Transport Layer (ETL), was systematically studied using the SCAPS-1D simulator. This structure achieved a maximum power conversion efficiency (PCE) of 20.88 %, with a current density (JSC) of 19.184 mAcm−2, a voltage (VOC) of 1.22 V, and a fill factor (FF) of 89.06. The valuable findings from our simulations will aid in the experimental design of an efficient Ca3NCl3-based new inorganic perovskite solar cell in the near future.