Giant transverse thermoelectric effect induced by topological transition in polycrystalline Dirac semimetal Mg 3 Bi 2

To achieve thermoelectric energy conversion, a large transverse thermoelectric effect in topological materials is crucial. However, a simple and effective way to manipulate the performance of transverse thermoelectric materials still remains elusive. Herein, we demonstrate a topological transition-induced giant transverse thermoelectric effect in polycrystalline Mn-doped Mg 3+ δ Bi 2 material, which has a competitively large transverse thermopower (617 μV K −1 ), power factor (20 393 μW m −1 K −2 ), magnetoresistance (16 600%), and electronic mobility (35 280 cm 2 V −1 s −1 ). The high performance is triggered by the modulation of the negative chemical pressure and disorder effects in the presence of Mn doping, which induces the transition from a topological insulator to a Dirac semimetal. The high-performance polycrystalline Mn-doped Mg 3+ δ Bi 2 described in this work robustly boosts the transverse thermoelectric effect through topological phase transition, paving a new avenue for the material design of transverse thermoelectricity.