Directional Thermal Diffusion Realizing Inorganic Sb2Te3/Te Hybrid Thin Films with High Thermoelectric Performance and Flexibility

Abstract

Inorganic films possess much higher thermoelectric performance than their organic counterparts, but their poor flexibilities limit their practical applications. Here, Sb2Te3/Tex hybrid thin films with high thermoelectric performance and flexibility, fabricated via a novel directional thermal diffusion reaction growth method are reported. The directional thermal diffusion enables rationally tuning the Te content in Sb2Te3, which optimizes the carrier density and leads to a significantly enhanced power factor of >20 µW cm–1 K–2, confirmed by both first-principles calculations and experiments; while dense boundaries between Te and Sb2Te3 nanophases, contribute to the low thermal conductivity of ≈0.86 W m–1 K–1, both induce a high ZT of ≈1 in (Sb2Te3)(Te)1.5 at 453 K, ranking as the top value among the reported flexible films. Besides, thin films also exhibit extraordinary flexibility. A rationally designed flexible device composed of (Sb2Te3)(Te)1.5 thin films as p-type legs and Bi2Te3 thin films as n-type legs shows a high power density of >280 µW cm–2 at a temperature difference of 20 K, indicating a great potential for sustainably charging low-power electronics.