An Approach to Improve the Computational Accuracy of Power Factor in Thermoelectric Energy Conversion

Thermoelectric technology is emerging as an novel technique and became very popular in the field of energy harvesting, especially the waste heat energy. The performance of any material for thermoelectric application can be analysed using the first principle technique significantly. The thermoelectric transport parameters are extracted by using the Boltzmann transport equations within the constant scattering time approximation. But this approach leads to the erroneous estimation of thermoelectric properties as it is a crude assumption of scattering time approximation. In the present work, for silicene and germanene, the scattering time of charge carriers is obtained as a function of temperature by investigating electron-phonon interactions from the first principles. Our calculations incorporate the interaction of the charge carriers with all the possible phonon modes, which gives an access to the highly precise scattering times. Incorporating the scattering times information in Onsager transport coefficients, thermoelectric transport properties are calculated based on the electronic band structure using HSE06 functional. To quantify the degree of inaccuracy occurred within constant scattering time approximation, the thermoelectric power factor is estimated using our proposed method and compared with constant scattering time.