Enhancing the Thermoelectric Properties of Conjugated Polymers by Suppressing Dopant-Induced Disorder

Suhao Wang, Wenjin Zhu, Ian E. Jacobs, William A. Wood, Zichen Wang, Suraj Manikandan, Jens Wenzel Andreasen, Hio-Ieng Un, Sarah Ursel, Sébastien Peralta, Shaoliang Guan, Jean-Claude Grivel, Stéphane Longuemart, Henning Sirringhaus

Abstract:

Doping is a crucial strategy to enhance the performance
of various organic electronic devices. However, in many cases, the
random distribution of dopants in conjugated polymers leads to the
disruption of the polymer microstructure, severely constraining the
achievable performance of electronic devices. Here, it is shown that by
ion-exchange doping polythiophene-based P[(3HT)1-x-stat-(T)x] (x = 0 (P1), 0.12 (P2), 0.24 (P3), and 0.36 (P4)), remarkably high electrical conductivity of >400 S cm−1 and power factor of >16 µW m−1 K−2
are achieved for the random copolymer P3, ranking it among highest ever
reported for unaligned P3HT-based films, significantly higher than that
of P1 (<40 S cm−1, <4 µW m−1 K−2). Although both polymers exhibit comparable field-effect transistor hole mobilities of ≈0.1 cm2 V−1 s−1 in the pristine state, after doping, Hall effect measurements indicate that P3 exhibits a large Hall mobility up to 1.2 cm2 V−1 s−1, significantly outperforming that of P1 (0.06 cm2 V−1 s−1). GIWAXS measurement determines that the in-plane π–π
stacking distance of doped P3 is 3.44 Å, distinctly shorter than that
of doped P1 (3.68 Å). These findings contribute to resolving the
long-standing dopant-induced-disorder issues in P3HT and serve as an
example for achieving fast charge transport in highly doped polymers for
efficient electronics.

External IDs:doi:10.1002/adma.202314062