Introducing atomistic dynamics at van der Waals surfaces for enhancing thermoelectric performance in layered Bi0.4Sb1.6Te3

Abstract

Thermoelectric (TE) enables the direct conversion of heat into electricity, but the performance of state-of-the-art layered materials has been limited due to restricted approaches to decoupling carrier and phonon transport. Here, a unique and never-looked feature of intralayer van der Waals bonds/interactions is explored for the atomistic/structural evolution and the transport properties of layered TE materials. The atomistic dynamics governing inversion in van der Waals layers/bonds is established as an innovative material engineering paradigm. We selected layered state-of-the-art Bi_0.4Sb1.6Te3 material as a representative prototype to reveal the intralayer transformative role in realizing high TE performance. The induced atomic diffusion at van der Waals layers and prevailed crystal-amorphicity duality optimize electronic and chemical environment with elevated carrier concentration and maintained Seebeck coefficient, which lead to an improved power factor of ≈ 49 µWcm−1K−2. Besides, the atomistic surface reconstruction/defects cause to reduce thermal conductivity to ≈0.97 Wm−1K−1 and in turn leading to an ultra-high figure of merit (ZTmax) of ≈1.54 at ~373 K. Thus, the present work provides a generic and practical avenue to open up a strategy by unique doping-dependent atomistic engineering, which is expected to be implemented in other layered structures to tailor the TE properties.