Optimization direction and selection strategy for thin film thermoelectric cooler materials

While thin-film thermoelectric coolers (TECs) are promising for chip thermal management, their material optimization strategy remains controversial. Conventional approaches focus on improving the material's figure of merit (ZT) by enhancing the power factor or reducing thermal conductivity, yet their relative effectiveness is unclear. Moreover, materials with identical ZT values can exhibit significantly different performance in practical devices, making selection criteria ambiguous. This study establishes a simulation model for thin-film TECs that incorporates contact and size effects, achieving a computational error of 3.33%. Through sensitivity analysis, we demonstrate that the optimal priority of thermophysical parameters (Seebeck coefficient, electrical resistivity, thermal conductivity) is condition-dependent: Under zero heat load and when the variations in material thermophysical properties are minor, the sensitivity of the Seebeck coefficient to ΔT is 2.9, which is higher than that of thermal conductivity (2.3) and electrical resistivity (0.5). Therefore, the optimization sequence should prioritize the Seebeck coefficient, followed by thermal conductivity and then electrical resistivity. Under heat load conditions, the sensitivity of the Seebeck coefficient remains consistently high (always greater than 2), indicating that it should still be optimized first. However, the optimal order for enhancing thermal conductivity and electrical resistivity depends on the magnitude of the heat flux density. This work provides a decisive material selection strategy beyond the ZT metric, guiding the performance optimization of thin-film TECs for high heat-flow scenarios. When selecting thin film thermoelectric materials with the same ZT, materials with lower thermal conductivity should be preferred under zero heat load, while materials with higher Seebeck coefficient should be preferred under high heat load. This study provides certain reference value for the development of high-performance thin-film thermoelectric materials.