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.