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<p>In this paper, the stability characteristics, electronic configuration, magnetic coupling mechanism, and optical properties of ZnS/ZnO heterojunctions doped with Cu<sup>2+</sup> and containing point defects (V<sub>Zn</sub>/V<sub>O</sub>/V<sub>S</sub>) were systematically investigated using first-principles calculations. Studies have shown that under Zn-rich conditions, the O-Zn interface containing oxygen vacancies (V<sub>O</sub>) achieves the highest stability, while under Cu-rich conditions, both O-Zn and S-Zn interfaces are viable. The O-Zn interface outperforms the S-Zn interface in both structural stability and band gap reduction capability. Cu<sup>2+</sup> doping on the ZnO side induces a more pronounced band gap narrowing effect than that on the ZnS side. The synergistic interaction between vacancy defects (V<sub>Zn</sub>/V<sub>O</sub>/V<sub>S</sub>) and Cu<sup>2+</sup> doping further narrows the band gap, with the minimum value reaching 1.23&#xa0;eV. In the Cu<sup>2+</sup>-doped O-Zn interface system containing V<sub>O</sub>/V<sub>Zn</sub>, the average ratio of the effective mass of holes to electrons (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:\stackrel{-}{D}\)</EquationSource> </InlineEquation>) can be achieved in the range of 1.58–1.83. A balance between light absorption and carrier separation is enabled by its moderate band gap (2.01–2.47&#xa0;eV), and the carrier separation efficiency is significantly enhanced. Furthermore, the visible light absorption edge of the system is redshifted to 692&#xa0;nm, with the maximum absorption coefficient reaching 2.45<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:\times\:\)</EquationSource> </InlineEquation>10<sup>5</sup> cm <sup>− 1</sup>. Magnetic analysis reveals that the magnetic core of the system is the unpaired electron of Cu<sup>2+</sup>-<i>3d</i><sup><i>9</i></sup>. During the charge compensation process between V<sub>O</sub>/V<sub>S</sub> and Cu<sup>2+</sup>, electrons are confined within the Cu-S coordination layer by the strong hybridization of Cu−3<i>d</i> and neighboring S−3<i>p</i> orbitals, as well as Coulombic attractive forces. The spin polarization effect is only manifested in this local structure. The strong electronegativity of the O-Zn interface partially suppresses the spin polarization of S−3<i>p</i> orbital electrons, with the net magnetic moment of the system maintained at 1–2 <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\:\mu\:\)</EquationSource> </InlineEquation><sub><i>B</i></sub>. In contrast, the weaker electronegativity of the S-Zn interface leads to reduced suppression of spin polarization, allowing the net magnetic moment to reach 4 <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\:\mu\:\)</EquationSource> </InlineEquation><sub><i>B</i></sub>.</p>

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First-Principles Study on Synergistic Regulation of Magnetic and Optical Properties by Defects (VZn/VO/VS) in Cu2+ Doped ZnS/ZnO Heterojunction

  • 期刊论文

  • 发表日期：

    2026年2月6日

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  • Miao Yu,
  • Yue Zhang,
  • Lei Zhang,
  • Fei Wang,
  • Cong Li

摘要

In this paper, the stability characteristics, electronic configuration, magnetic coupling mechanism, and optical properties of ZnS/ZnO heterojunctions doped with Cu2+ and containing point defects (VZn/VO/VS) were systematically investigated using first-principles calculations. Studies have shown that under Zn-rich conditions, the O-Zn interface containing oxygen vacancies (VO) achieves the highest stability, while under Cu-rich conditions, both O-Zn and S-Zn interfaces are viable. The O-Zn interface outperforms the S-Zn interface in both structural stability and band gap reduction capability. Cu2+ doping on the ZnO side induces a more pronounced band gap narrowing effect than that on the ZnS side. The synergistic interaction between vacancy defects (VZn/VO/VS) and Cu2+ doping further narrows the band gap, with the minimum value reaching 1.23 eV. In the Cu2+-doped O-Zn interface system containing VO/VZn, the average ratio of the effective mass of holes to electrons ( \(\:\stackrel{-}{D}\) ) can be achieved in the range of 1.58–1.83. A balance between light absorption and carrier separation is enabled by its moderate band gap (2.01–2.47 eV), and the carrier separation efficiency is significantly enhanced. Furthermore, the visible light absorption edge of the system is redshifted to 692 nm, with the maximum absorption coefficient reaching 2.45 \(\:\times\:\) 105 cm − 1. Magnetic analysis reveals that the magnetic core of the system is the unpaired electron of Cu2+-3d9. During the charge compensation process between VO/VS and Cu2+, electrons are confined within the Cu-S coordination layer by the strong hybridization of Cu−3d and neighboring S−3p orbitals, as well as Coulombic attractive forces. The spin polarization effect is only manifested in this local structure. The strong electronegativity of the O-Zn interface partially suppresses the spin polarization of S−3p orbital electrons, with the net magnetic moment of the system maintained at 1–2 \(\:\mu\:\) B. In contrast, the weaker electronegativity of the S-Zn interface leads to reduced suppression of spin polarization, allowing the net magnetic moment to reach 4 \(\:\mu\:\) B.