A new criterion for dual-objective optimization of thermoelectric devices

In recent years, remarkable strides have been made in the thermoelectric (TE) materials field. Mirco TE devices (micro-TEDs) fabricated from TE materials have attracted substantial attention owing to their promising applications in energy harvesting and thermal management fields. The design of the geometric structure in micro-TEDs serves as a crucial link bridging the thermoelectric properties of materials and the overall performance of these micro-TEDs. In this work, the minimum distance criterion (C_md) was proposed to achieve relatively high-power density (P_d) and efficiency (η) at the same cross-sectional area ratio (x) and current (I). 5 pairs of n-type and p-type TE materials including Bi₂Te₃, Cu₂Se + LAST, half-Heusler, Mg₃Sb₂, and SnSe were used to simulate the micro-TEDs. When x = 0.9, the Bi₂Te₃-based micro-TEDs can possess a relatively higher P_d,max and η_max at the same I. According to the C_md criterion, for the Cu₂Se + LAST and SnSe micro-TEDs, the values of P_d,max, η_max, ΔT_max, and Q_cd,max can be increased by approximately 20 % compared to those of the x = 1.0 micro-TEDs. C_md value is an effective descriptor to optimize cross-sectional area ratio of n-type and p-type TE legs for micro-TEDs.