Thin Film Organic Thermoelectric Generator Based on Tetrathiotetracene

Abstract

Thin films of p-and n-type organic semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene (TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition of thin films or by post-deposition doping using controlled exposure to iodine vapors. Thermal co-deposition in vacuum of TTT and TCNQ is used to prepare n-type thin films. The attained thin films are characterized by measurements of Seebeck coefficient and electrical conductivity. Seebeck coefficient and conductivity could be varied by altering the doping level. P-type TTT:iodide thin films with a power factor of 0.52 μWm -1 K -2 , electrical conductivity of 130 S m -1 and Seebeck coefficient of 63 μV K -1 and n-type TCNQ:TTT films with power factor of 0.33 μWm -1 K -2 , electrical conductivity of 57 S m -1 and Seebeck coefficient of -75 μV K -1 are produced. Engineered deposition of both p-and n-type thermoelectric conducting elements on the same substrate is demonstrated. A proof of concept prototype of planar thin film TE generator based on a single p-n couple from the organic materials is built and its power generation characterized.

Flexible Organic Thermoelectric Materials and Devices for Wearable Green Energy Harvesting

“…Thin p- and n-type organic semiconductor films for thermoelectrical applications are fabricated by doping tetrathiotetracene (TTT) [125]. To obtain p-type materials, TTT was doped with iodine during vacuum deposition, while for n-type thin films, thermal co-deposition in vacuum of tetracyanoquinodimethane (TCNQ) and TTT was used.…”

Enhancing doping efficiency by improving host-dopant miscibility for fullerene-based n-type thermoelectrics

“…Compared with the progress made on p-doping, n-doping is lagging behind due to the difficulty in finding efficient dopants for n-type semiconductors, which could partially account for the current situation that, unlike their p-type counterparts, [22][23][24][25][26][27][28][29][30][31][32] the development of n-type organic thermoelectric materials have not progressed rapidly, [33][34][35][36] but which is required for practical thermoelectric device applications. Most of the reported n-dopants thus far, such as reactive alkali metals, cationic dyes, or organometallic complexes, either possess poor ambient stability or require strict vacuum processing.…”

Capturing Waste Heat Energy with Charge-Transfer Organic Thermoelectrics

“…The poor solubility of TTT material makes vacuum deposition of thin films more attractive as gas-phase doping also allows preparation of both the nand p-legs (Figure 4, b) into a functioning in-plane generator (Figure 4, c). 30 Only very small amounts of power (50 pW at 1 mV) are attained by the device in Figure 4. Greater amounts of power in such thin-film configurations would be attained by use of multiple junctions in series or by increasing the thickness and length of the p/n legs.…”