General Screening Rules and Segmented Optimization Strategy for Efficient Thermoelectric Devices Validated by Mg 3 (Sb,Bi) 2 /Bi 0.5 Sb 1.5 Te 3 ‐GeTe Module

Abstract Segmentation is a widely adopted strategy to enhance the efficiency of medium‐ and high‐temperature thermoelectric devices by capitalizing on the distinct properties of materials across various temperature ranges. Establishing a highly compatible matching relationship is crucial for maximizing conversion efficiency. In this study, the concepts of materials’ compatibility factor and relative current density into the screening process are emphasized for universal adaptability. The effectiveness and practicality of the theoretical model for optimal segmented combinations are validated through COMSOL finite element simulations and experimental results. A segmented thermoelectric power generation device is constructed that integrates the environmentally friendly n‐type Mg 3 (Sb,Bi) 2 with the optimal segmented pairing of Bi 0.5 Sb 1.5 Te 3 ‐GeTe. Notably, at a temperature difference of Δ T = 440 K, this device achieves a maximum conversion efficiency of 10.4% and a peak output power of 0.41 W. These findings provide a solid theoretical foundation for the development of efficient combinations of thermoelectric materials.