  The search for semiconductors with high thermoelectric figure of merit has
been greatly aided by theoretical modeling of electron and phonon transport,
both in bulk materials and in nanocomposites. Recent experiments have studied
thermoelectric transport in ``strongly correlated'' materials derived by doping
Mott insulators, whose insulating behavior without doping results from
electron-electron repulsion, rather than from band structure as in
semiconductors. Here a unified theory of electrical and thermal transport in
the atomic and ``Heikes'' limit is applied to understand recent transport
experiments on sodium cobaltate and other doped Mott insulators at room
temperature and above. For optimal electron filling, a broad class of
narrow-bandwidth correlated materials are shown to have power factors (the
electronic portion of the thermoelectric figure of merit) as high at and above
room temperature as in the best semiconductors.
