The modern study of thermoelectric materials offers two important targets: from one side the research is oriented to the development of materials with increased adimensional figure of merit, ZT, providing an improvement in energy conversion efficiency in order to make thermoelectric technology more appealing for larger scale operations. On the other hand, a hard challenge is represented by the research of novel materials based on cheaper, more reliable and less hazardous elements. This second objective is at the base of different attempts of overcoming the modern consolidated thermoelectric technology with its limits often related to the materials involved.