Remarkable conductivity enhancement in P-doped polythiophenes via rational engineering of polymer-dopant interactions

Jongho Kim, Jing Guo, Gjergji Sini*, Michael Korning Sørensen, Jens Wenzel Andreasen, Kai Lin Woon, Veaceslav Coropceanu, Sri Harish Kumar Paleti, Huan Wei, Sébastien Peralta, Mohamed Mallouki, Christian Müller, Yuanyuan Hu*, Thanh Tuan Bui, Suhao Wang*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Molecular doping is an effective approach to tune the charge density and optimize electrical performance of conjugated polymers. However, the introduction of dopants, on the other hand, may disturb the polymer microstructure and disrupt the charge transport path, often leading to a decrease of charge carrier mobility and deterioration of electrical conductivity of the doped films. Here we show that dopant-induced disorder can be overcome by rational engineering of polymer-dopant interactions, resulting in remarkable enhancement of electrical conductivity. Benchmark poly(3-hexylthiophene) (P3HT) and its analogous random polymers of 3-hexylthiophene and thiophene P[(3HT)1-x-stat-(T)x] were synthesized and doped by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Remarkably, random P[(3HT)1-x-stat-(T)x] was doped to a far superior electrical conductivity, that in the case of x ≥ 0.24, the conductivity of P[(3HT)1-x-stat-(T)x] is over 100 times higher than that of the doped P3HT, despite both P3HT and P[(3HT)1-x-stat-(T)x] exhibit comparable charge carrier mobility in their pristine state and in spite of their practically identical redox properties. This result can be traced back to the formation of π-stacked polymer-dopant-polymer co-crystals exhibiting extremely short packing distances of 3.13–3.15 Å. The mechanism behind these performances is based on a new role played by the dopant molecules that we name “bridging-gluing”. The results are coherently verified by the combination of optical absorption spectroscopy, X-ray diffraction, density functional theory calculations, and molecular dynamics simulations.
Original languageEnglish
Article number100360
JournalMaterials Today Advances
Volume18
Number of pages14
DOIs
Publication statusPublished - 2023

Keywords

  • Conducting polymers
  • Charge-transport
  • Doping
  • Aggregations
  • DFT calculations

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