Enhanced thermoelectric properties of 3D printed Bi2Te2.7Se0.3 by atomic interface engineering

Abstract

The performance of n-type Bi2Te3 materials prepared by selective laser melting (SLM) 3D printing technology tends to be lower than p-type materials. Herein, a bottom-up interface engineering strategy based on Atomic Layer Deposition (ALD) is presented to improve the properties of n-type Bi2Te2.7Se0.3 (BTS) materials prepared by SLM. To validate this strategy, a ZnO ultrathin layer was applied to the grain boundaries of BTS, synergistically optimizing carrier/phonon transport. In terms of electrical transport, the energy filtering effect triggered by the constructed ZnO/BTS interface effectively enhances the Seebeck coefficient of the Bi2Te3 material printed by SLM, substantially increasing the power factor. Additionally, the high thermal stability of the ALD-deposited ZnO ultrathin layer effectively suppresses the volatilization of Te in BTS, regulating the carrier concentration. Regarding thermal transport properties, the multiscale defects introduced by the non-equilibrium solidification process during SLM printing cause effective phonon scattering across a wide frequency range, which in turn reduces the thermal conductivity of the material. Atomic-level interface modification in SLM-printed BTS enhanced the ZT value to 1.25. Exploiting this superior thermoelectric performance, a thermoelectric module was constructed. It demonstrated a conversion efficiency of 5.7 % with a temperature difference of 200 K, comparable to the advanced Bi2Te3-based thermoelectric modules. The integration of an ALD interface modification strategy with SLM technology has not only demonstrated potential applications in Bi2Te3-based thermoelectric material development, but also bears significant importance for the accelerated advancement of high-performance thermoelectric materials in other systems.