Study on the optoelectronic properties of ZrS₂/h-BN composite ceramics: improved ceramic design

In this study, density functional theory (DFT) calculations were employed to systematically investigate the geometric structures, electronic properties, strain responses, and optical absorption performances of ZrS₂/h-BN composite ceramic heterojunctions. Three heterojunction models were constructed: bilayer ZrS₂/h-BN, trilayer ZrS₂/h-BN/ZrS₂, and h-BN/ZrS₂/h-BN. All three were found to be direct bandgap semiconductors with bandgaps of 0.763 eV, 0.544 eV, and 0.626 eV, respectively, which are significantly narrowed compared to their monolayer counterparts. By examining the difference in charge density across the interface alongside the electrostatic potential profiles, it was demonstrated that electrons spontaneously migrated from the h-BN monolayer toward the ZrS₂ monolayer. Biaxial strain modulation demonstrated that compressive strain widened the bandgap while tensile strain narrowed it. Among the structures, ZrS₂/h-BN/ZrS₂ exhibited the strongest strain sensitivity, with its bandgap decreasing to 0.337 eV under +2% strain. Optical absorption calculations showed that the trilayer heterojunction achieved an absorption coefficient as high as 2.5 × 10⁵ cm^-1 in the ultraviolet-visible region, approximately three times higher than that of the monolayer ZrS₂, and tensile strain induced a significant red shift. This work provides theoretical guidance and material design strategies for developing high-performance, bandgap-tunable novel composite ceramic optoelectronic devices.

All first-principles calculations were performed using the CASTEP code. The norm-conserving pseudopotential method based on density functional theory was employed to describe the interactions between ion cores and valence electrons. The electron exchange-correlation energy was parameterized using the PBE functional within the GGA. To obtain more accurate electronic band structures and optical properties, the HSE06 hybrid functional was used to correct the bandgap after convergence of the self-consistent field calculations.