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<p>This study explores the electronic and optical properties of the double perovskite K<sub>2</sub>AgSbI<sub>6</sub> under external electric fields using first-principles density functional theory (DFT) calculations. The material exhibits a cubic Fm3̅m crystal structure, providing essential structural context for its properties. Calculations were performed using the generalized gradient approximation with the Perdew–Burke–Ernzerhof functional (GGA-PBE) and the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional within the CASTEP code. K<sub>2</sub>AgSbI<sub>6</sub> exhibits an indirect gap that decreases systematically with field due to a Stark effect: from 0.597 eV (HSE06, 0 V/Å) to 0.231 eV (0.5 V/Å). Field-induced changes in the orbital-projected density of states highlight enhanced K-state participation near the band edges. The optical properties, including the dielectric function, absorption coefficient, refractive index, and optical conductivity, exhibit substantial tunability under applied fields across the visible–ultraviolet (UV) range. For instance, the absorption coefficient in the visible region rises from 6.3 × 10<sup>4</sup> to 8.7 × 10<sup>4</sup> cm<sup>−1</sup> at 2.8 eV between 0 V/Å and 0.5 V/Å. These results establish K<sub>2</sub>AgSbI<sub>6</sub> as a strongly electro-optic responsive platform suitable for field-effect optical modulators and photodetectors, and they delineate materials-engineering routes (chemical substitution, strain) to tailor the bandgap for other applications.</p>

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Novel Insights into the Electric Field-Driven Electronic and Optical Behavior of K2AgSbI6 via DFT

  • 期刊论文

  • 发表日期：

    2026年1月4日

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  • Abdelmounaim Laassouli,
  • Mohamed Karouchi,
  • Abdelkebir Ejjabli,
  • Aymane El Haji,
  • Hamza Errahoui,
  • Youssef Lachtioui,
  • Omar Bajjou

摘要

This study explores the electronic and optical properties of the double perovskite K2AgSbI6 under external electric fields using first-principles density functional theory (DFT) calculations. The material exhibits a cubic Fm3̅m crystal structure, providing essential structural context for its properties. Calculations were performed using the generalized gradient approximation with the Perdew–Burke–Ernzerhof functional (GGA-PBE) and the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional within the CASTEP code. K2AgSbI6 exhibits an indirect gap that decreases systematically with field due to a Stark effect: from 0.597 eV (HSE06, 0 V/Å) to 0.231 eV (0.5 V/Å). Field-induced changes in the orbital-projected density of states highlight enhanced K-state participation near the band edges. The optical properties, including the dielectric function, absorption coefficient, refractive index, and optical conductivity, exhibit substantial tunability under applied fields across the visible–ultraviolet (UV) range. For instance, the absorption coefficient in the visible region rises from 6.3 × 104 to 8.7 × 104 cm−1 at 2.8 eV between 0 V/Å and 0.5 V/Å. These results establish K2AgSbI6 as a strongly electro-optic responsive platform suitable for field-effect optical modulators and photodetectors, and they delineate materials-engineering routes (chemical substitution, strain) to tailor the bandgap for other applications.