Unveiling pressure-driven modulations in Ca3NBr3: Insights into physical properties and solar cell performance

Abstract

This study employs first-principles calculations using Quantum Espresso to investigate the structural, thermodynamic, electrical, mechanical, and optical properties of the halide-based perovskite Ca₃NBr₃ under varying pressures (−6 % to +6 %). Additionally, SCAPS-1D simulations were conducted to evaluate its solar cell performance. This comprehensive approach provides insights into the material's potential for photovoltaic applications and its behavior under mechanical stress, advancing our understanding of halide-based perovskites. The final enthalpy and elastic constants confirmed the thermodynamic and mechanical stability of Ca₃NBr₃, indicating its ductile nature. Without biaxial pressure, Ca₃NBr₃ maintains a semiconductor bandgap of 1.128 eV. Under compressive strain (−6 %), the bandgap narrows to 0.998 eV, causing a redshift in the absorption peaks. Conversely, tensile strain (+6 %) widens the bandgap to 1.315 eV, resulting in a blueshift. Additionally, as pressure increases from tensile to compressive, there is a rise in elastic constants, average sound velocity, bulk modulus, shear modulus, ductility, Pugh's ratio, Poisson's ratio, anisotropy, Young's modulus, and Elastic Debye temperature. Furthermore, the optical absorption, Loss function, both the imaginary and real components of the dielectric functions, conductivity, and refractive index, and reflectivity, for cubic perovskite Ca₃NBr₃ were analyzed in detail under pressures ranging from −6 % to +6 %. Increased pressure caused the compound to transition to a conductor and improve its absorption capabilities in the 4–20 eV range, making it suitable for UV spectrum applications. A new solar cell device featuring a Ca₃NBr₃ absorber layer and WS₂ electron transport layer achieved a maximum power conversion efficiency (PCE) of 30.82 %, with a V_OC of 0.894 V, a J_SC of 41.81 mA/cm², and a fill factor (FF) of 82.46 %. Additionally, the effects of temperature and realistic resistances on the Ca₃NBr₃ materials were calculated. The findings position Ca₃NBr₃ as a promising candidate for advanced optoelectronic applications, including UV absorbers and high-performance solar cells.