Multiple Valence Bands Convergence and Localized Lattice Engineering Lead to Superhigh Thermoelectric Figure of Merit in MnTe

Abstract

MnTe has been considered a promising candidate for lead‐free mid‐temperature range thermoelectric clean energy conversions. However, the widespread use of this technology is constrained by the relatively low‐cost performance of materials. Developing environmentally friendly thermoelectrics with high performance and earth‐abundant elements is thus an urgent task. MnTe is a candidate, yet a peak ZT of 1.4 achieved so far is less satisfactory. Here, a remarkably high ZT of 1.6 at 873 K in MnTe system is realized by facilitating multiple valence band convergence and localized lattice engineering. It is demonstrated that SbGe incorporation promotes the convergence of multiple electronic valence bands in MnTe. Simultaneously, the carrier concentration can be optimized by SbGeS alloying, which significantly enhances the power factor. Simultaneously, MnS nanorods combined with dislocations and lattice distortions lead to strong phonon scattering, resulting in a markedly low lattice thermal conductivity(κlat) of 0.54 W m K−1, quite close to the amorphous limit. As a consequence, extraordinary thermoelectric performance is achieved by decoupling electron and phonon transport. The vast increase in ZT promotes MnTe as an emerging Pb‐free thermoelectric compound for a wide range of applications in waste heat recovery and power generation.

Thermal and electrical transport properties of two-dimensional Dirac graphenylene: a first-principles study

“…8 A high ZT is a key requirement of TE materials to be used as promising candidates for energy harvesting. 9,10 However, the S and κ parameters of TE materials are interrelated, making the independent control of these variables to improve ZT difficult. 11 For example, the large effective mass of carriers increases S , but reduces the electrical conductivity, and the reduction of electrical conductivity leads to a decrease in the electronic contribution to κ , which is consistent with the Wiedemann–Franz law: κ e = LσT (where L is the Lorentz constant).…”

Realizing high-performance thermoelectric modules through enhancing the power factor via optimizing the carrier mobility in n-type PbSe crystals

“…Hitherto, predominant strategies for enhancing thermoelectric performance have focused on intricately balancing these parameters. These strategies encompass manipulations of the band structure to bolster electrical transport properties 9–11 or the design of defect structures to reduce thermal conductivity. 12–14 However, these aforementioned strategies inevitably lead to a deterioration in carrier mobility, a critical factor closely tied to the power factor.…”