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

International audience ; Inorganic films possess much higher thermoelectric performance than their organic counterparts, but their poor flexibilities limit their practical applications. Here, Sb2Te3/Te-x 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 mu W 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 approximate to 0.86 W m(-1) K-1, both induce a high ZT of approximate to 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 mu W cm(-2) at a temperature difference of 20 K, indicating a great potential for sustainably charging low-power electronics.