Research Progress of Thermoelectric Materials—A Review

Thermoelectric materials are functional materials that directly convert thermal energy into electrical energy or vice versa, and due to their inherent properties, they hold significant potential in the field of energy conversion. In this review, we examine several fundamental strategies aimed at enhancing the conversion efficiency, classification, preparation methods, and applications of thermoelectric materials. First, we introduce an important parameter for evaluating the performance of thermoelectric materials, the dimensionless quality factor ZT, and present the theory of electroacoustic transport in thermoelectric materials, which provides the foundation for enhancing the performance of thermoelectric materials. Second, strategies for optimizing electroacoustic transport properties, carrier concentration, energy band engineering, phonon engineering, and entropy engineering are summarized, emphasizing that energy band engineering presents numerous possibilities for enhancing thermoelectric material performance by tuning the carrier effective mass, energy band convergence, and energy band resonance. By analyzing the importance of various optimization strategies, it is concluded that co-optimization is the primary method for improving the performance of thermoelectric materials in the future. In addition, an overview of the currently available thermoelectric materials is provided, including two categories, classical thermoelectric materials and novel thermoelectric materials, along with a highlight of two thermoelectric material preparation techniques. Finally, the principles of thermoelectric technology are illustrated, its applications in various fields are discussed, problems in the current research are analyzed, and future trends are outlined. Overall, this paper provides a comprehensive summary of optimization strategies, material classifications, and applications, offering valuable references and insights for the researchers in this field, with the aim of further advancing the development of thermoelectric material science.