Issue 16, 2022

Lewis acid–base pair doping of p-type organic semiconductors

Abstract

Doping is required to increase the electrical conductivity of organic semiconductors for uses in electronic and energy conversion devices. The limited number of commonly used p-type dopants suggests that new dopants or doping mechanisms could improve the efficiency of doping and provide new means for processing doped polymers. Drawing on Lewis acid–base pair chemistry, we combined Lewis acid dopant B(C6F5)3 (BCF) with the weak Lewis base benzoyl peroxide (BPO). The detailed behavior of p-type doping of the model polymer poly(3-hexylthiophene) (P3HT) with this Lewis acid–base pair in solution was examined. Solution 19F-NMR spectra confirmed the formation of the expected counterion, as well as side products from reactions with solvent. BCF : BPO was also found to efficiently dope a range of semiconducting polymers with varying chemical structures demonstrating that the BCF : BPO combination has an effective electron affinity of at least 5.3 eV. In thin films of regioregular P3HT cast from the doped solutions, delocalized polarons formed due to the large counterions leading to a large polaron-counterion distance. At and above 0.2 eq. BCF : BPO doping, amorphous areas of the film became doped, disrupting the structural order of the films. Despite the change in structural order, thin films of regioregular P3HT doped with 0.2 eq. BCF : BPO had a conductivity of 25 S cm−1. This study demonstrates the effectiveness of a two-component Lewis acid–base doping mechanism and suggests additional two-component Lewis acid–base chemistries should be explored.

Graphical abstract: Lewis acid–base pair doping of p-type organic semiconductors

Supplementary files

Article information

Article type
Paper
Submitted
12 Feb 2022
Accepted
21 Mar 2022
First published
06 Apr 2022

J. Mater. Chem. C, 2022,10, 6287-6295

Author version available

Lewis acid–base pair doping of p-type organic semiconductors

K. A. Peterson and M. L. Chabinyc, J. Mater. Chem. C, 2022, 10, 6287 DOI: 10.1039/D2TC00605G

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