Enhanced thermoelectricity by controlled local structure in bismuth-chalcogenides

Spectroscopic techniques, including photoelectron spectroscopy, diffuse reflectance, and x-ray absorption, are used to investigate the electronic structure and the local structure of LaOBiS$_{2-x}$Se$_x$ thermoelectric material. It is found that Se substitution effectively suppresses local distortion, that can be responsible for the increased carrier mobility together with a change in the electronic structure. The results suggest a possible way to control thermoelectric properties by tuning of the local crystal structure of these materials.