Evaluation of energy filtering effect from first principles calculations

Abstract

Energy filtering effect is usually utilized in composites to enhance the thermoelectric performance, and a reliable theoretical approach is needed to predict the optimum parameters related to this effect. By taking Bi2Te3 as an example, we show that first principles calculations and Boltzmann transport equations can be used to evaluate energy filtering effect, and the optimal values for the maximum power factor of interfacial potential barrier height (Eb) and carrier scattering probability (p) can be calculated precisely. The calculation results show that the power factor can be greatly enhanced at high carrier concentrations by energy filtering. This enhancement is sensitive to Eb and p: to achieve 40% power factor enhancement, Eb must be in the range 0.06–0.10 eV, and p should be greater than 60%. The optimal Eb also shows weak dependence on p. Our approach can be easily applied to other materials due to the generality of first principles calculations, and will aid high throughput screening for new thermoelectric composites.