Thermoelectric Properties of Nanostructured Tetrathiotetracene Iodide Crystals: 3D Modeling

Abstract

A more complete three-dimensional (3D) physical model for nanostructured crystals of tetrathiotetracene iodide, TTT 2 I 3 , is presented. The restrictions on the thermoelectric figure of merit ZT that this model involves are determined. At the same time, the criteria of application of simplified 1D model are defined more precisely. In TTT 2 I 3 crystals the carriers are holes. As earlier, two interaction mechanisms of holes with acoustic phonons are considered, generalized for 3D case. One interaction is similar to that of polaron and other to that of deformation potential. Interaction of carriers with impurities and defects is also taken into account. Along chains (x direction) the transport mechanism is of the band type, but in the transversal directions it is of hopping type. The electrical conductivity σ xx , the thermopower (Seebeck coefficient) S xx , the electronic thermal conductivity e xx  and (ZT) xx along the conductive chains have been modelled for the first time in the 3D model. Optimal parameters which predict a considerable increase of (ZT) xx are determined.

Non-conventional charge transport in organic semiconductors: magnetoresistance and thermoelectricity

“…41 Organic materials whose thermoelectric properties have been studied 42 include polymers such as poly(thienothiophene), 43 poly(ethylene-dioxythiophene) [44][45][46][47][48][49][50] (PEDOT), polyaniline, 51 poly(pphenylene vinylene) derivatives, 52,53 poly(3-hexylthiophene), 1,54 carbazole polymers, [55][56][57] metal coordination polymers, 58 and P(NDIOD-T2) 59 , as well as small molecules such as fullerenes, [60][61][62][63] perylene diimide derivatives and organic salts based on TTF, TCNQ, BEDT-TTF and tetrathiotetracene amongst others. 44,[64][65][66][67][68][69][70] Of these, PEDOT has recently shown excellent performance as a p-type thermoelectric material with ZT reported up to 0.42 71 . On the other hand, there has not been so much success in finding good n-type organic thermoelectric materials.…”

Peierls Structural Transition in Q1D Organic Crystals of TTT<SUB>2</SUB>I<SUB>3</SUB> for Different Values of Carrier Concentration

“…Recently, it was shown that Advances in Materials Physics and Chemistry highly conducting Quasi-One-Dimensional (Q1D) organic crystals can have different promising thermoelectric applications [4] [5]. It was predicted in [6] that the values of dimensionless thermoelectric figure of merit ~4 could be realized after optimization of carrier concentration in TTT 2 I 3 organic crystals. On the other hand, it is well known that organic nanomaterials have large potential applications in electronic, sensing, energy-harnessing and quantum-scale systems [7].…”