Energy filtering-induced ultrahigh thermoelectric power factors in Ni$_3$Ge

TL;DR

This paper introduces a novel materials design principle to achieve ultrahigh thermoelectric power factors in Ni3Ge by engineering electronic band structures to induce energy filtering, supported by DFT screening and experimental validation.

Contribution

It presents a new design approach for thermoelectric materials using band structure engineering to induce energy filtering, leading to high power factors in Ni3Ge and related compounds.

Findings

Ultrahigh power factors up to 11 mW/mK^2 near room temperature achieved.

Energy filtering mechanism driven by intrinsic phonon interactions identified.

A multi-step DFT screening method discovered new high-performance thermoelectric compounds.

Abstract

Traditional thermoelectric materials rely on low thermal conductivity to enhance their efficiency but suffer from inherently limited power factors. Novel pathways to optimize electronic transport are thus crucial. Here, we achieve ultrahigh power factors in Ni$_3$Ge through a new materials design principle. When overlapping flat and dispersive bands are engineered to the Fermi level, charge carriers can undergo intense interband scattering, yielding an energy filtering effect similar to what has long been predicted in certain nanostructured materials. Via a multi-step DFT-based screening method developed herein, we discover a new family of L1$_2$-ordered binary compounds with ultrahigh power factors up to 11 mW m$^{-1}$ K$^{-2}$ near room temperature, which are driven by an intrinsic phonon-mediated energy filtering mechanism. Our comprehensive experimental and theoretical study of these new intriguing materials paves the way for understanding and designing high-performance scattering-tuned metallic thermoelectrics.