A possibility to realize a high thermoelectric figure of merit in quasi-one-dimensional organic crystals

A. Casian, V. Dusciac, R. Dusciac

Department of Computers, Informatics and Microelectronics, Technical University of Moldova, MD-2004 Chisinau, Moldova

Organic materials attract in the last years an enhanced interest as materials with more diverse and often unusual electronic properties. In particular, we have recently demonstrated theoretically that under certain conditions it is possible to obtain in quasi-one-dimensional (Q1D) organic semiconductors rather high values of carriers mobility and of the thermoelectric figure of merit ZT. In the present paper we investigate the thermoelectric opportunities of some highly conducting Q1D organic crystals. Materials of n- and p-type are considered. The electrical conductivity, Seebeck coefficient, electronic thermal conductivity and Lorentz number are investigated as functions of crystal parameters. Obtained dependences are used to determine the optimal expected values of ZT at room temperature. The mechanism for ZT enhancement and the needed tuning of crystal parameters in order to maximize the enhancement are analyzed in detail. It is shown that due to the interference of two main electron-phonon interaction mechanisms, the values as high as ZT ~ 20 are possible both in n- and p- type Q1D materials. Recommendations are elaborated for the realization of such materials.