Atomic-scale tuning oxygen-doped Bi2Te2.7Se0.3 to simultaneously enhance seebeck coefficient and electrical conductivity
Manipulation of oxygen-related impurities is an extreme challenge for most of thermoelectric materials, especially for those possessing nanostructure, since which normally result in the degradation of the thermoelectric performance. Here, we demonstrate that by atomic-scale controlling the oxygen doping in the form of dislocation clusters in Bi2Te2.7Se0.3 (BTS) thermoelectric material, the trade-off between Seebeck coefficient and electrical conductivity is broken, resulting in the simultaneously enhanced Seebeck coefficient and electrical conductivity as well as the suppressed thermal conductivity. As a consequence, a maximum ZT of 0.91 is achieved, which is approximately 1.4 times higher than that of pristine BTS. Based on HR-STEM investigation, the oxygen-related dislocation clusters can be unambiguously identified and we argue that the optimized carrier/phonon transport behavior can be attributed to the multifunctionality of oxygen-related dislocation clusters in BTS acting as electron donors, electron energy filters and phonon blockers. Our work provides a clear microscopic understanding on the role of oxygen doping in modifying phonons/carriers transport behavior in BTS thermoelectric material, which provides an efficient avenue for designing high performence thermoelectric material.