An Overview of Thermoelectric Concepts

Abstract

Thermoelectric (TE) materials have emerged as promising candidates for addressing the global energy crisis by enabling waste heat recovery and sustainable cooling technologies. The performance of TE materials is governed by the dimensionless figure of merit ZT = α² σ T / κ, which depends on three key interrelated parameters: the Seebeck coefficient (α), electrical conductivity (σ), and thermal conductivity (κ). Due to the conflicting nature of these interconnected variables, simultaneous optimization of all three parameters remains elusive. Two main strategies have been introduced to improve ZT: phonon engineering and band engineering. The ultimate goal of these approaches is to develop phonon-glass and electron-crystal materials. Among the well-studied families of thermoelectric materials are chalcogenides (e.g., Bi₂Te₃, PbTe, and SnSe), skutterudites (e.g., CoSb₃), Zintl phases (e.g., Yb₁₄MnSb₁₁), and half-Heuslers (e.g., ZrNiSn), each offering distinct advantages across different temperature regimes. Despite considerable progress, a unified understanding of structure-property relationships remains elusive, motivating growing interest in computational methods. The design, prediction, and discovery of new and improved thermoelectric materials increasingly rely on density functional theory and machine learning, which complement experimental efforts by accelerating the identification of high-performance candidates. In this overview, we revisit the fundamental concepts and theories underlying these materials along with their key design strategies and applications.