Unusual Transport and Impact of Nonparabolic Electronic Band Structure on the Thermoelectric Performance in n‐Type In4Se3‐Based Thermoelectric Materials

Abstract

Unusual thermoelectric (TE) transport in n‐type In4Se3 has been reported in the context of first‐principles electronic structure calculation and Boltzmann transport theory. The density of states (DOS) shows certain peaks due to a nontopological Mexican hat and parabolic capping around the edges of Kane bands. The effect of such hard shifts of bands shows anomalously high Seebeck coefficient (S = 550 μV K−1 at ≈1017 cm−3) at room temperature due to very slow decreasing S and rapidly increasing DOS effective mass with carrier concentration compared to that obtained from Kane and parabolic band model. The best TE performance is predicated in Kane transport region (≈1018 cm−3) over the wide range of temperature, 300–700 K. The calculated values of relaxation time (≈10−14 s at 660 K), electrical conductivity, power factor and figure of merit in iodine‐doped sample and those obtained from the rigid band model of pure sample show excellent agreement with the reported experimental results.