In this lecture, the evolution of the thermoelectric figure of merit ZT during the last decades is analyzed. The possibilities to increase ZT are described. The realizations of main ideas, as the use of heavy atom masses and complex unit cells, alloy scattering of phonons, bulk nanostructuring, phonon glass/electron crystal, quantum confinement of electrons, film nanostructuring and band engineering are presented. The charge and energy transport in highly conducting organic materials is described. It is shown theoretically that the Q1D organic crystals on the basis of p-type tetrathiotetracene–iodide, TTT₂ I₃ and n-type tetrathiotetracene-tetracyanoquinodimethane TTT(TCNQ)₂, after additional purification and optimization of carrier concentration, may have good thermoelectric properties. Bibl. 31, Fig. 10.