Thermally Induced Formation of HF4TCNQ– in F4TCNQ-Doped Regioregular P3HT
- 23 July 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry Letters
- Vol. 11 (16), 6586-6592
- https://doi.org/10.1021/acs.jpclett.0c01673
Abstract
The prototypical system for understanding doping in solution-processed organic electronics has been poly(3-hexylthiophene) (P3HT) p-doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Multiple charge transfer states, defined by the fraction of electron transfer to F4TCNQ, are known to coexist and are dependent on polymer molecular weight, crystallinity, and processing. Less well understood is the loss of conductivity after thermal annealing of these materials. Specifically, in thermoelectrics, F4TCNQ-doped regioregular (rr) P3HT exhibits significant conductivity losses at temperatures lower than other thiophene-based polymers. Through detailed spectroscopic investigation of progressively heated P3HT films co-processed with F4TCNQ, we demonstrate that this diminished conductivity is due to formation of the non-chromophoric, weak dopant HF4TCNQ-. This species is likely formed through hydrogen abstraction from the alpha aliphatic carbon of the hexyl chain at the 3-position of thiophene rings of rr-P3HT. This reaction is eliminated for polymers with ethylene glycol-containing side chains, which retain conductivity at higher operating temperatures. In total, these results provide a critical materials design guideline for organic electronics.Funding Information
- King Abdullah University of Science and Technology
- Achievement Rewards for College Scientists Foundation
- Eli Lilly and Company
- Division of Materials Research (DMR-1608289)
This publication has 48 references indexed in Scilit:
- Organic and solution-processed tandem solar cells with 17.3% efficiencyScience, 2018
- Long‐Lived Flexible Displays Employing Efficient and Stable Inverted Organic Light‐Emitting DiodesAdvanced Materials, 2018
- High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiencyNature Energy, 2018
- Over 14% Efficiency in Polymer Solar Cells Enabled by a Chlorinated Polymer DonorAdvanced Materials, 2018
- High thermoelectric power factor from multilayer solution-processed organic filmsApplied Physics Letters, 2018
- Influence of crystallinity on the thermoelectric power factor of P3HT vapour-doped with F4TCNQRSC Advances, 2018
- Molecular Optimization Enables over 13% Efficiency in Organic Solar CellsJournal of the American Chemical Society, 2017
- Impact of the Doping Method on Conductivity and Thermopower in Semiconducting PolythiophenesAdvanced Energy Materials, 2014
- Polymer solar cellsNature Photonics, 2012
- In situ measurement of power conversion efficiency and molecular ordering during thermal annealing in P3HT:PCBM bulk heterojunction solar cellsJournal of Materials Chemistry, 2011