In situ crystal-amorphous compositing inducing ultrahigh thermoelectric performance of p-type Bi0.5Sb1.5Te3 hybrid thin films

Flexible Bi0.5Sb1.5Te3-based thermoelectric thin films are promising p-type candidates for applications in flexible and wearable electronics. Here, we use thermal evaporation deposition and subsequent post-annealing treatment to prepare Bi0.5Sb1.5Te3 crystal-amorphous hybrid thin films. Tuning the annealing temperature can achieve an optimized hybrid level between amorphous and crystalline Bi0.5Sb1.5Te3, leading to an optimized figure of merit as high as ~1.5 at room temperature, which is an ultrahigh value in the p-type Bi0.5Sb1.5Te3 thin films. Our single parabolic band model and Density-Functional Theory calculation results indicate that such a high value should be attributed to the high effective mass induced by the proper crystal-amorphous hybrid structure. Our study indicates that a crystal-amorphous compositing can be used as a new methodology to achieve ultrahigh performance in thermoelectric materials. [Display omitted] •Prepare p-type amorphous Bi0.5Sb1.5Te3 film composed of nanopillar arrays.•Controlling crystallinity by tuning annealing temperature.•Crystal-amorphous optimization enhances m* and S.•DFT calculation identifies that the enhanced m* is due to band flattening.•Approaching zT of ~1.5 and amorphous κl of ~0.35 W m−1 K-1 (at 300K).