Regulation of Anderson localization for enhancing thermoelectric properties in Mn doped AgSbSe2 compounds†

Abstract

So far, the influence of Anderson localization on the thermoelectric performance of materials has been somewhat ambiguous. Herein, we establish that doping with Mn significantly weakens the Anderson localization in AgSbSe₂. The temperature dependent electronic transport properties of Mn-doped AgSbSe₂ compounds document an Anderson localization–delocalization transition that is revealed by three distinct stages: variable-range hopping conduction, nearest-neighbor hopping conduction, and band conduction. Doping AgSbSe₂ compounds with Mn reduces the electronic localization barrier and shifts electron localization to a lower temperature range. Such mitigation of the Anderson localization effect greatly improves the electrical transport properties. Ultimately, the electrical conductivity was increased from 1.01 × 10³ Ω⁻¹ m⁻¹ at room temperature for pristine AgSbSe₂ to 1.28 × 10⁴ Ω⁻¹ m⁻¹ for AgSb_0.96Mn_0.04Se₂. Consequently, the power factor was improved from 0.11 mW m⁻¹ K⁻² to 0.52 mW m⁻¹ K⁻², which corresponds to a fivefold increase compared to pristine AgSbSe₂. In conjunction with the intrinsically low lattice thermal conductivity of AgSbSe₂, the AgSb_0.98Mn_0.02Se₂ sample reaches the highest zT value of 1.1 at 690 K, which is more than a threefold increase in comparison with that of pristine AgSbSe₂. This work demonstrates that effective modulation of the Anderson localization can be an effective approach to improve the thermoelectric performance of materials.