Temperature dependences of the thermoelectric power factor of TTT2I3 organic crystals

Abstract

The organic crystals of p – type of tetrathiotetracene-iodide (TTT2I3) are very prospective for thermoelectric applications. The internal structure consists of segregate linear TTT molecular chains spaced at approximately 0.9 nm one from other. In the chain direction, the distance between the nearest TTT molecules is ~ 0.25 nm, and the overlap of electronic wavefunctions provide a narrow conduction band in this direction. The electrical conductivity is highly anisotropic and is mainly provided by TTT chains. Two most important electron-phonon interaction mechanisms are considered: of the deformation potential type and of the polaron type. The thermoelectric properties can be significantly enhanced by optimizing the structural composition of the crystal.