Novel Thermal Diffusion Temperature Engineering Leading to High Thermoelectric Performance in Bi 2 Te 3 -Based Flexible Thin-Films.

Flexible Bi 2 Te 3 -based thermoelectric devices can function as power generators for powering wearable electronics or chip-sensors for internet-of-things. However, the unsatisfied performance of n-type Bi 2 Te 3 flexible thin films significantly limits their wide application. In this study, a novel thermal diffusion method is employed to fabricate n-type Te-embedded Bi 2 Te 3 flexible thin films on flexible polyimide substrates, where Te embeddings can be achieved by tuning the thermal diffusion temperature and correspondingly result in an energy filtering effect at the Bi 2 Te 3 /Te interfaces. The energy filtering effect can lead to a high Seebeck coefficient ≈160 µV K -1 as well as high carrier mobility of ≈200 cm 2 V -1 s -1 at room-temperature. Consequently, an ultrahigh room-temperature power factor of 14.65 µW cm -1 K -2 can be observed in the Te-embedded Bi 2 Te 3 flexible thin films prepared at the diffusion temperature of 623 K. A thermoelectric sensor is also assembled through integrating the n-type Bi 2 Te 3 flexible thin films with p-type Sb 2 Te 3 counterparts, which can fast reflect finger-touch status and demonstrate the applicability of as-prepared Te-embedded Bi 2 Te 3 flexible thin films. This study indicates that the thermal diffusion method is an effective way to fabricate high-performance and applicable flexible Te-embedded Bi 2 Te 3 -based thin films.