Giant transverse thermoelectric effect induced by topological transition in polycrystalline Dirac semimetal Mg3Bi2

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 Mg3+δBi2 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 cm2 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 Mg3+δBi2 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.