Electronic structure and optical property of Cd\(_{2-x}\)Y\(_{x}\)SnO4 using the first-principles calculation

IF 1.6 4区物理与天体物理 Q3 PHYSICS, CONDENSED MATTER

The European Physical Journal B Pub Date : 2025-01-29 DOI:10.1140/epjb/s10051-025-00868-8

Mei Tang, Cuilian Wen

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Abstract

The electronic structure and optical properties of Cd_2-xY_xSnO₄ are studied using the first-principle calculation within the generalized-gradient approximation and the Coulomb repulsion effect. Three defect models are constructed by Y atom occupying Cd sites. The energy band shows that the 4d electrons of Y atom mainly affect the bottom of conduction band. The density of state reveals that the 4d state of Y atom hybridizes with the O 2p and Cd 5s states at the bottom of conduction band. With the increment of the substitution numbers, Y 4d states increases gradually to enhance the hybrid intensity. The average effective mass of Cd_1.875Y_0.125SnO₄ model attains 0.352m₀, which is lower than 0.484m₀ of Cd₂SnO₄. It indicates that the conductivity of Cd₂SnO₄ is improved by Y occupying Cd site. Moreover, the absorption edges of Cd_1.9375Y_0.0625SnO₄ and Cd_1.875Y_0.125SnO₄ models blueshift to induce optical transmittance reaching about 90% in the visible light region. Therefore, Cd_1.875Y_0.125SnO₄ can be applied to prepare a short wavelength optical device in future.

Graphical abstract

As the substitution concentration increases, both the conduction band and the valence band move to the low energy direction. The band gap value of Cd_1.9375Y_0.0625SnO₄ is 2.19 eV, which is the closest to the band gap value of Cd₂SnO₄. The band gap value decreases slightly with increasing substitution concentration of Y at Cd site. Compared with the effective mass m* of Cd₂SnO₄, the effective mass m* decreases after the entry of Y atoms. It indicates that Y atoms substitution has a certain improvement for the conductivity of Cd₂SnO₄. The transmittance of Cd_1.9375Y_0.0625SnO₄ and Cd_1.875Y_0.125SnO₄ models can attain 90%, which is somewhat higher than that of Cd₂SnO₄.