Ca掺杂HgS的DFT+U研究：面向高性能光伏应用的带隙调控与光学特性

Abstract This research investigates the functional characteristics of Ca doped HgS (Hg 1 − x Ca x S) compounds across different calcium concentrations ( X= 0 to 1 in the difference of 0.25) using DFT (Density Functional Theory) calculations. The study employs the GGA + U (Generalized Gradient Approximation with U correction) methodology with the PBE (Perdew–Burke–Ernzerhof) functional to ensure accurate electronic structure predictions. The inclusion of Hubbard U corrections enhances the accuracy of electronic structure predictions by addressing the underestimation of the bandgap inherent in conventional GGA. Calcium incorporation in HgS provides a promising route to fine-tune its electronic and optical characteristics for high-performance optoelectronic applications. However, the systematic impact of Ca doping across various concentrations remains largely unexplored. This work investigates the influence of Ca substitution on the semiconductor behavior of HgS, revealing a direct bandgap corresponding to Gamma point ( Γ − Γ ), which rises with rising Ca content. In addition, the material exhibits promising optical properties, such as high absorption coefficients, low reflectivity, and reduced energy loss across the visible and ultraviolet spectral ranges characteristics that are crucial for efficient light harvesting in optoelectronic and photovoltaic devices. These results demonstrate that Ca doping effectively tunes the optoelectronic behavior of HgS, offering a practical pathway for bandgap engineering. Consequently, the study provides valuable insights into the structure property relationship in Hg 1 − x Ca x S, addressing critical gaps in the understanding of its functional behavior and guiding future material design for high-performance solar energy applications. The incorporation of Ca into Hg 1 − x Ca x S (where x = 0 . 75 ) significantly enhances the band gap ( E g ) and absorption coefficient ( α ), with Hg 0.25 Ca 0.75 S exhibiting an optimal E g of ∼ 1.13 eV closely aligning with the Shockley–Queisser limit for maximum single-junction solar cell efficiency.