The Effects Of Pressure And Doping On The Structural, Electronic, Phonon, Optical, Thermoelectric, And Superconducting Properties Of Yttrium Hydrogen Selenide (Yhse): First Principles Study

Abstract

Yttrium Hydrogen Selenide Shows Multifunctional Behavior Under High Pressure And La Doping, Making It A Promising Material For Next-Generation Superconducting, Thermoelectric, And Optoelectronic Applications. This Study Explores The Structural, Electronic, Phonon, Optical, Superconducting, And Thermoelectric Properties Of Yhse Under Pressure And La Doping Using Density Functional Theory, Phonopy, Phono3py, Boltztrap, And Python-Based Tools. With Increasing Pressure, Structural Analysis Reveals A Contraction Of Interatomic Distances And A Reduction In Lattice Parameters. Electronic Band Structure Calculations Indicate That, Pressure-Induced Modulation Of Localized States Drives A Transition From An Indirect To A Direct Band Gap At High Pressures. Phonon Dispersion Analysis Shows An Overall Stiffening Of Lattice Vibrations, Although Certain High-Symmetry Modes Exhibit Softening. Moreover, Enhanced Electron-Phonon Coupling Under High Pressure Can Lead To An Increase In The Superconducting Transition Temperature (Tc). Additionally, Pressure Induces Notable Modifications In Most Optical Properties, Particularly Enhancing Absorption In The Uv Region. Furthermore, Pressure Enhances Thermoelectric Performance, Achieving A Notable Maximum Figure Of Merit (Zt) Of 0.79. On The Other Hand, Lanthanum (La) Doping Modifies The Crystal Structure By Causing Lattice Expansion Along The C-Axis, Leading To An Increased C A Ratio And Structural Anisotropy, Which Can Influence Electronic And Transport Behavior. La Doping Also Raises The Density Of States Near The Fermi Level And Introduces Localized States Within The Band Gap. Phonon Mode Softening Induced By Doping Reduces The Lattice Thermal Conductivity, Thereby Enhancing Thermoelectric Efficiency. Additionally, Lanthanum Doping Raises The Superconducting Critical Temperature (Tc), Providing A Viable Alternative To Pressure-Induced Superconductivity. Moreover, Optical Analysis Reveals That Doping Induces Significant Enhancements In The Key Optical Parameters. Furthermore, Thermoelectric Calculations Indicate Enhanced Performance, With The Figure Of Merit Reaching, Zt 0.75. These Dft Results Reveal Crucial Functional Properties Of The Material Relevant To Optoelectronic, Thermoelectric, And Energy Storage Applications