Electron structure and density of states’ calculations of Ag₂S and Ag₂Se crystals from first-principle

Abstract

The results of calculations of the electron structure for Ag2S and Ag2Se crystals from first-principle in the framework of density functional theory (DFT) are presented in this work. The origin of the bands from [Formula: see text] and [Formula: see text] electron states of Ag, S and Se atoms are investigated. It was established that the orthorhombic Ag2Se crystal shows semiconductor properties in P2221 and P212121 space groups and semimetallic properties in Im-3m space groups with cubic crystal system. Monoclinic crystal type of Ag2S shows semiconductor properties in P21/c space group. However, semimetallic properties manifested itself in monoclinic Ag2S in P21 and cubic Ag2S structure in Im-3m phases.

Significant Improvement in Thermoelectric Performance of AgInSe2-Based Composites through In Situ Formation of Ag2Se

“…The reduction in μ is mainly attributed to an increased carrier scattering and energy barrier in the heterojunction AgInSe 2 /Ag 2 Se . Although both the n H and μ values of the pristine AgInSe 2 at RT are scattered, they are comparable to those reported previously. ,,− The enhancement in n H is mainly ascribed to the contribution of the Ag 2 Se species with a very small indirect band gap. − ,, Further, it is also due to the fact that Ag can inject electrons into the conduction band of the Ag 2 Se and CuAgSe phases. , …”

“…17,18,20−23 The enhancement in n H is mainly ascribed to the contribution of the Ag 2 Se species with a very small indirect band gap. [24][25][26]44,45 Further, it is also due to the fact that Ag can inject electrons into the conduction band of the Ag 2 Se and CuAgSe phases. 35,36 TE Performance.…”

Advances in Ag2Se-based thermoelectrics from materials to applications

“…The theoretical calculation based on the first-principles density functional theory (DFT) shows that α-Ag 2 Se is a typical semiconductor with a narrow E g . 186 The calculation used a pseudo-potential method by implementing the general-gradient approximation (GGA) in the Quantum Wise program package. 186 Fig.…”

“…186 The calculation used a pseudo-potential method by implementing the general-gradient approximation (GGA) in the Quantum Wise program package. 186 Fig. 4(a) plots the band structure of α-Ag 2 Se with a space group of P 2 1 2 1 2 1 , 186 in which the conduction band minimum and the valence band maximum are located between the symmetry points of Γ – Z and Γ – U , while the fundamental absorption edge was formed by indirect transitions.…”

“…186 Fig. 4(a) plots the band structure of α-Ag 2 Se with a space group of P 2 1 2 1 2 1 , 186 in which the conduction band minimum and the valence band maximum are located between the symmetry points of Γ – Z and Γ – U , while the fundamental absorption edge was formed by indirect transitions. 186 The calculated E g is small for α-Ag 2 Se, agreeing well with the experimental result of 0.03 eV.…”