According to various aspects, exemplary embodiments are provided of thermoelectric materials, which embodiments may have improved figure of merit. In one exemplary embodiment, a thermoelectric material generally includes bismuth telluride nanoparticles, which may be undoped or doped with at least one or more of silver, antimony, tin, and/or a combination thereof. The bismuth telluride nanoparticles may be dispersed in a matrix material comprising particulate bismuth telluride. Methods for making undoped and doped bismuth telluride nanoparticles are also disclosed, which may include a solvothermal method for making bismuth telluride nanoparticles having a size ranging from 1 to 200 nanometers.