RT journal article
T1 Synthesis and Thermoelectric Properties of 2- and 2,8-Substituted Tetrathiotetracenes
A1 Garret, Mary Robert
A1 Durán Peña, María Jesús
A1 Lewis, William
A1 Pudzs, Kaspars
A1 Uzulis, Janis
A1 Mihailovs, Igors
A1 Tyril, Björk
A1 Shine, Jonathan
A1 Rutkis, Martins
A1 Woodward, Simon
A2 Química Orgánica
K1 tetratiotetracene
K1 thermoelectric properties
AB Reaction of elemental sulfur with 2-R1 and 2,8-R1,R2-substituted tetracenes (2) in refluxing DMF affords 5,6,11,12 tetrathiotetracenes (1) in good yields (74-99%) for a range of substituents where R1,R2 are: H,H (a); Me,H (b); MeO,H (c); Ph,H (d); Me,Me (e), Me,iPr (f, iPr = iso-propyl, CHMe2), Me,MeO (g); MeO,MeO (h). The reaction rate is limited only by the solubility of the tetracene (2); 2g-h being both the least soluble and slowest reacting. At partial conversion recovered single crystalline 2g led to its X-ray structure determination. Vacuum deposited (substrate deposition temperature 300 K, pressure 7 × 10 6 mbar, source temperature 500 K) thin films from 1 (of initial 88-99% purity) show final electrical conductivities, σ(in plane) from 1.40 × 10-5 S cm-1 (1g) to 3.74 × 10-4 S cm-1 (1b) for the resultant near pristine films; while 1d proved too involatile to be effectively sublimed under these conditions. In comparison, initially 95% pure TTT (1a) based films show σ(in plane) = 4.33 × 10-5 S cm-1. The purities of 1a-h are highly upgraded during sublimation. Well defined micro-crystallites showing blade, needle or mossy like habits are observed in the films. The Seebeck coefficients (Sb) of the prepared 1 range from 374 (1c) to 900 (1f) μV K-1 (vs. 855 μV K-1 for identically prepared 95% pure TTT, 1a). Doping of films of 1f (R1 = Me, R2 = iPr) with iodine produces optimal p-type behaviour: σ(in-plane) = 7.00 × 10-2 S cm 1, Sb = 175 μV K-1. The latter’s Power Factor (PF) at 0.327 μW m-1 K 2 is more than 500-times that of the equivalent I2-doped TTT films (1a, R1 = R2 = H), previously regarded as the optimal material for thin film thermoelectric devices using acene radical cation motifs.
PB ROYAL SOC CHEMISTRY
SN 2050‐7534
YR 2018
FD 2018
LK http://hdl.handle.net/10498/30398
UL http://hdl.handle.net/10498/30398
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 21-sep-2026