Thermoelectric figure-of-merit barrier at minimum lattice thermal conductivity?

An analysis of the transport properties data on established thermoelectric materials indicates that the ratio of the electrical power factor to optimu m electrical conductivity appears constant. This result, when combined with the previously proposed concept of a minimum thermal conductivity, enables realistic maximum dimensionless figures-of-merit to be calculated. It is c oncluded that a barrier to increasing the dimensionless figure-of-merit app ears to exist which is around 2 at room temperature and that overcoming thi s barrier will require the development of materials with radically differen t transport properties from those currently available. (C) 2000 American In stitute of Physics. [S0003-6951(00)02132-X].