First-Principles Insights into the Relative Stability, Physical Properties, and Chemical Properties of MoSe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Molybdenum diselenide (MoSe2) is a transition-metal dichalcogenide (TMDC) with significant potential in electrochemical, photocatalytic, and optoelectronic applications.
• Existing research lacks comprehensive studies on the structural stability of various MoSe2 polymorphs, hindering their practical implementation.

Purpose of the Study:

• To systematically investigate and compare the relative structural stability of eleven different MoSe2 polymorphs.
• To analyze the physical properties of these polymorphs and assess their suitability for real-world applications.

Main Methods:

• First-principles calculations based on density functional theory (DFT) were employed.
• Calculations included band structure, phonon dispersion, elastic constants, and electronic properties using the HSE06 hybrid functional.
• Analysis of charge density, charge transfer, and electron localization function elucidated bonding characteristics.

Main Results:

• Four MoSe2 polymorphs (1H, 2H, 2T, and 3Hb) were predicted to be stable based on mechanical and dynamical properties.
• Polymorphs 4T and 3Ha, while dynamically stable, were found to be mechanically unstable, indicating a metastable state.
• Calculated band gaps for several polymorphs (1H, 2H, 3Ha, 3Hb, 2T, 4T, 2R1) ranged from 1.6-1.8 eV, aligning with experimental values for 2H-MoSe2.

Conclusions:

• The study provides the first comprehensive analysis of MoSe2 polymorph stability, identifying key candidates for advanced applications.
• The findings offer crucial insights into the mechanical, dynamical, electronic, and thermal properties of MoSe2 polymorphs.
• The identified stable polymorphs are promising for further experimental validation and integration into functional devices.