Effects of Counter‐Ion Size on Delocalization of Carriers and Stability of Doped Semiconducting Polymers. (28th October 2020)

• Record Type: Journal Article
• Authors: Thomas, Elayne M.; Peterson, Kelly A.; Balzer, Alex H.; Rawlings, Dakota; Stingelin, Natalie; Segalman, Rachel A.; Chabinyc, Michael L.
• Is Part Of: Advanced Electronic Materials. Volume 6:Number 12(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-28
• Subjects: doping -- electrical conductivity -- semiconducting polymers; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.202000595
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: Since doped polymers require a charge‐neutralizing counter‐ion to maintain charge neutrality, tailored and high degrees of doping in organic semiconductors requires an understanding of the coupling between ionic and electronic carrier motion. A method of counter‐ion exchange is utilized using the polymeric semiconductor poly[2, 5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3, 2‐b]thiophene] ‐C14 to deconvolute the effects of ionic/polaronic interactions with the electrical properties of doped semiconducting polymers. In particular, exchanging the counter‐ions of the dopant nitrosonium hexafluorophosphate enables investigation into the role of counter‐ion size from 5.2 to 8.2 Å in diameter. The orientational order of the polymeric crystallites is not affected with this exchange process while effectively modifying the counter‐ion distance to the charge carrier. Doped films have electrical conductivities of 320 S cm −1 and are not sensitive to an increased ion‐polaron distance. It is posited that other factors dominate the electrical properties at a device scale, such as the morphology and presence of domain boundaries. Interestingly, the temperature stability of the doped film can be drastically improved with the use of counter‐ions containing less labile bonds. This platform serves as a unique way to retain the morphology of polymeric thin films while studying charge interactions at the local scale. Abstract : The distance between the counter‐ion and charge carrier in semiconducting polymers has been predicted to shift the polaron absorbance and suggested to affect electrical properties. Here, the polaron absorbance is found to shift with counter‐ion size, but the electrical conductivity is relatively unchanged in doped semiconducting polymers with unchanged morphology.