Optimized Thermoelectric Cooler Performance by the Structure-Matching Design of Asymmetrical p/n-Type Legs

Commercial Bi₂Te₃-based thermoelectric (TE) coolers typically comprise equal-size p- and n-type legs. However, this traditional structure limits the cooling temperature differences of TE coolers (TECs) due to identical current density, when their electrical or thermal characteristics differ significantly. This work presents a novel design of p- and n-type TE legs to optimize the performance of TECs. The cooling properties of the materials are initially calculated by theoretical equations and then evaluated by using a combination of finite element simulations and experiments. The research findings suggest that by utilizing higher ZT p-type materials to enhance the TEC cooling performance, further optimization of the ratio of the cross-sectional area of the TE legs (A_p/A_n) improves the structural matching of the legs, which achieves the maximum figure of merit Z and leads to a 5.4% increase in cooling power density. Additionally, the TEC with optimized A_p/A_n increases the cooling temperature difference by 3.3 and 2.7 K for the same current at hot side temperatures of 300 and 315 K, respectively, while the coefficient of performance remains unchanged. Moreover, the maximum cooling temperature difference reaches 70 and 74 K, respectively. We anticipate that our results will guide the design and optimization of the TECs.