Unveiling the recently synthesis noncentrosymmetric layered ASb3X2O12 (A = K, Rb, Cs, Tl; X = Se, Te) via first principles calculations

Abstract

This study explores the structural, optical, and thermoelectric properties of non-centrosymmetric layered selenite and tellurite compounds KSb₃Se₂O₁₂, RbSb₃Se₂O₁₂, CsSb₃Se₂O₁₂, TlSb₃Se₂O₁₂, KSb₃Te₂O₁₂, RbSb₃Te₂O₁₂, CsSb₃Te₂O₁₂, TlSb₃Te₂O₁₂ to assess their potential for sustainable and renewable energy technologies. The selenite and tellurite compounds feature distinct non-centrosymmetric layered crystal structures, which are key to their unique optical and electronic properties. The materials display a layered structure without a center of symmetry, characterized by distinct atomic arrangements, and their band gaps vary depending on the constituent elements. For selenites, band gaps range from 2.97 eV to 3.19 eV, while for tellurites, they range from 2.75 eV to 3.02 eV, indicate their suitability for indirect semiconducting applications. The investigated materials exhibit high absorbance in the ultraviolet region, suggesting they are promising for solar cell applications. The energy loss function peaks at 14 eV, indicating minimal optical loss in the infrared and visible spectra. The static dielectric constants ε₁(0) were calculated, showing variations based on the elemental composition. The response of ε₂(ω) demonstrates strong interactions in the ultraviolet region, corresponding to electronic transitions from the valence to the conduction bands. Thermoelectric properties, evaluated with the BoltzTrap code using transport theory. The Seebeck coefficient of p-type semiconductors typically increases with temperature, but TlSb₃Se₂O₁₂ shows an even greater increase, suggesting enhanced thermoelectric properties. Both selenites and tellurites have rising electrical conductivities, with ASb₃Se₂O₁₂ peaking at 800 K. The Power Factor improves with temperature, reaching a peak for TlSb₃Se₂O₁₂. These compounds exhibit favorable electrical conductivity and power factor, suggesting potential applications in thermoelectric systems. The figure of merit (ZT) values spanning from 0.90 to 1.51, with a maximum ZT value of 1.41 at 800 K, TlSb₃Se₂O₁₂ shows great potential for high-temperature thermoelectric applications. These findings advance the understanding of non-centrosymmetric oxide materials and provide valuable insights for developing advanced materials for energy technologies.