Abstract

This study presents a comprehensive first-principles investigation of the structural, electronic and optical properties of monolayer Mo1–xWxS₂ alloys, systematically exploring the full compositional range (x = 0 to 1) using density functional theory (DFT). We establish that these alloys are thermodynamically stable and maintain the characteristic 2H crystal structure with minimal structural perturbation upon alloying. A key finding is the preservation of a direct bandgap at the K-point across all compositions. This gap exhibits continuous tunability, increasing near-monotonically from 1.696 eV (MoS₂) to 1.858 eV (WS₂), a critical feature for tailoring optoelectronic devices. Electronic structure analysis reveals the systematic evolution of the orbital contributions of transition metal d and sulfur p at the edges of the band with composition. Consequently, the optical spectra, evaluated up to 8 eV, show a progressive blueshift in the main features of the interband transition with increasing W content, accompanied by predictable changes in key optical constants. Our comprehensive results validate the monolayer Mo1–xWxS₂ as an electronically versatile platform that offers fine control over electronic and optical properties via alloying, making these tunable direct-gap semiconductors highly promising for next-generation photodetectors, light emitters, and potentially flexible optoelectronic applications exploiting their 2D nature.

Abstract

This study presents a comprehensive first-principles investigation of the structural, electronic and optical properties of monolayer Mo1–xWxS₂ alloys, systematically exploring the full compositional range (x = 0 to 1) using density functional theory (DFT). We establish that these alloys are thermodynamically stable and maintain the characteristic 2H crystal structure with minimal structural perturbation upon alloying. A key finding is the preservation of a direct bandgap at the K-point across all compositions. This gap exhibits continuous tunability, increasing near-monotonically from 1.696 eV (MoS₂) to 1.858 eV (WS₂), a critical feature for tailoring optoelectronic devices. Electronic structure analysis reveals the systematic evolution of the orbital contributions of transition metal d and sulfur p at the edges of the band with composition. Consequently, the optical spectra, evaluated up to 8 eV, show a progressive blueshift in the main features of the interband transition with increasing W content, accompanied by predictable changes in key optical constants. Our comprehensive results validate the monolayer Mo1–xWxS₂ as an electronically versatile platform that offers fine control over electronic and optical properties via alloying, making these tunable direct-gap semiconductors highly promising for next-generation photodetectors, light emitters, and potentially flexible optoelectronic applications exploiting their 2D nature.

Abstract

This study presents a comprehensive first-principles investigation of the structural, electronic and optical properties of monolayer Mo1–xWxS₂ alloys, systematically exploring the full compositional range (x = 0 to 1) using density functional theory (DFT). We establish that these alloys are thermodynamically stable and maintain the characteristic 2H crystal structure with minimal structural perturbation upon alloying. A key finding is the preservation of a direct bandgap at the K-point across all compositions. This gap exhibits continuous tunability, increasing near-monotonically from 1.696 eV (MoS₂) to 1.858 eV (WS₂), a critical feature for tailoring optoelectronic devices. Electronic structure analysis reveals the systematic evolution of the orbital contributions of transition metal d and sulfur p at the edges of the band with composition. Consequently, the optical spectra, evaluated up to 8 eV, show a progressive blueshift in the main features of the interband transition with increasing W content, accompanied by predictable changes in key optical constants. Our comprehensive results validate the monolayer Mo1–xWxS₂ as an electronically versatile platform that offers fine control over electronic and optical properties via alloying, making these tunable direct-gap semiconductors highly promising for next-generation photodetectors, light emitters, and potentially flexible optoelectronic applications exploiting their 2D nature.

Abstract

This study presents a comprehensive first-principles investigation of the structural, electronic and optical properties of monolayer Mo1–xWxS₂ alloys, systematically exploring the full compositional range (x = 0 to 1) using density functional theory (DFT). We establish that these alloys are thermodynamically stable and maintain the characteristic 2H crystal structure with minimal structural perturbation upon alloying. A key finding is the preservation of a direct bandgap at the K-point across all compositions. This gap exhibits continuous tunability, increasing near-monotonically from 1.696 eV (MoS₂) to 1.858 eV (WS₂), a critical feature for tailoring optoelectronic devices. Electronic structure analysis reveals the systematic evolution of the orbital contributions of transition metal d and sulfur p at the edges of the band with composition. Consequently, the optical spectra, evaluated up to 8 eV, show a progressive blueshift in the main features of the interband transition with increasing W content, accompanied by predictable changes in key optical constants. Our comprehensive results validate the monolayer Mo1–xWxS₂ as an electronically versatile platform that offers fine control over electronic and optical properties via alloying, making these tunable direct-gap semiconductors highly promising for next-generation photodetectors, light emitters, and potentially flexible optoelectronic applications exploiting their 2D nature.