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<p>Alloying engineering offers a powerful route to tailor the multifunctional properties of chalcogenide perovskites for optoelectronic applications. This work presents a comprehensive first-principles investigation of the structural, electronic, optical, and elastic properties of orthorhombic CaHf<sub>1-x</sub>Ge<sub>x</sub>S<sub>3</sub> (x = 0.00, 0.25, 0.50, 0.75, 1.00) using density functional theory with on-site Coulomb correction (DFT + U) and density-functional perturbation theory (DFPT). All compositions preserve the orthorhombic <i>Pnma</i> framework, while Ge substitution induces lattice contraction and enhanced covalency. Negative formation energies and calculated Goldschmidt tolerance factors confirm both thermodynamic and structural stability across the alloy series. Electronic structure analysis revealed semiconducting behavior with band gaps tunable within the range of <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(1.84 - 0.59eV\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1.84</mn> <mo>-</mo> <mn>0.59</mn> <mi>e</mi> <mi>V</mi> </mrow> </math></EquationSource> </InlineEquation>. While the gap generally decreases with Ge substitution, a specific electronic transition/structural variation is observed at <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(x=0.75\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>=</mo> <mn>0.75</mn> </mrow> </math></EquationSource> </InlineEquation>. Mechanical analysis demonstrates that B-site alloying drives a transition from brittle to ductile behavior, while optical studies show good light absorption, high optical conductivity, and increased reflectivity, highlighting suitability for photovoltaics, photodetectors, and light-emitting devices. This study establishes CaHf<sub>1-x</sub>Ge<sub>x</sub>S<sub>3</sub> as a versatile and designable platform for next-generation optoelectronic materials, demonstrating that controlled B-site substitution can precisely tune structural, electronic, and optical properties in sulfide perovskites.</p>

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Alloying enhanced structural, electronic, elastic and optical properties of CaHf1-xGexS3 (x = 0.00, 0.25, 0.50, 0.75, and 1.00) chalcogenide perovskites for Optoelectronic Applications: First Principle Study

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • Mulugetta Duressa Kassa

摘要

Alloying engineering offers a powerful route to tailor the multifunctional properties of chalcogenide perovskites for optoelectronic applications. This work presents a comprehensive first-principles investigation of the structural, electronic, optical, and elastic properties of orthorhombic CaHf1-xGexS3 (x = 0.00, 0.25, 0.50, 0.75, 1.00) using density functional theory with on-site Coulomb correction (DFT + U) and density-functional perturbation theory (DFPT). All compositions preserve the orthorhombic Pnma framework, while Ge substitution induces lattice contraction and enhanced covalency. Negative formation energies and calculated Goldschmidt tolerance factors confirm both thermodynamic and structural stability across the alloy series. Electronic structure analysis revealed semiconducting behavior with band gaps tunable within the range of \(1.84 - 0.59eV\) 1.84 - 0.59 e V . While the gap generally decreases with Ge substitution, a specific electronic transition/structural variation is observed at \(x=0.75\) x = 0.75 . Mechanical analysis demonstrates that B-site alloying drives a transition from brittle to ductile behavior, while optical studies show good light absorption, high optical conductivity, and increased reflectivity, highlighting suitability for photovoltaics, photodetectors, and light-emitting devices. This study establishes CaHf1-xGexS3 as a versatile and designable platform for next-generation optoelectronic materials, demonstrating that controlled B-site substitution can precisely tune structural, electronic, and optical properties in sulfide perovskites.