A pyridine-capped quaterthiophene as an alternative to PEDOT:PSS, processable from organic solvents and without acidity, for more stable electronic devices

Hussien, E. J., Cameron, J. , Findlay, N. J. , Taylor, R. G.D., Johnson, M., Kanibolotska, L., Kanibolotsky, A. L. and Skabara, P. J. (2023) A pyridine-capped quaterthiophene as an alternative to PEDOT:PSS, processable from organic solvents and without acidity, for more stable electronic devices. Materials Horizons, 10(11), pp. 5087-5098. (doi: 10.1039/D3MH01060K) (PMID:37681478)

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a material that has become ubiquitous in the field of organic electronics. It is most commonly used as a hole transport layer (HTL) in optoelectronic devices and can be purchased commercially in various formulations with different properties. Whilst it is a most convenient material to work with, there are stability issues associated with PEDOT:PSS that are detrimental to device stability and these are due to the acidic nature of the PSS component. In this paper, we present a molecular, non-acidic alternative to PEDOT:PSS. The parent structure is composed of a quater(3,4-ethylenedioxythiophene) unit capped either side of the short chain with two pyridine units. This compound, termed (BEDOTPy)2, can be prepared chemically and electrochemically to give doped materials with a choice of counteranions. Further functionalisation via quaternisation at the nitrogen atoms allows for modification of solubility and film-forming properties. The conductivity of the doped samples can reach up to 3.75 S cm−1. The materials are non-acidic and are therefore attractive alternatives to PEDOT:PSS for device applications. We demonstrate an OLED device using the compound (BEDOTPy-EtOH-I)2PF6 as an HTL, and compare the device performance to one made with PEDOT:PSS. Due to the non-acidic nature of the molecular material, the corresponding OLED device does not show a drop in luminance over time, whereas a loss of performance is observed for the device containing PEDOT:PSS over a short period. These results are presented to introduce the parent compound (BEDOTPy)2 as an attractive alternative to PEDOT:PSS, which can be easily modified chemically to provide a plethora of potential compounds with tunable properties.

• Item Type: Articles
• Additional Information: The authors thank EPSRC for funding through grants EP/T022477/1 and EP/R03480X/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Johnson, Mr Michael and Cameron, Dr Joseph and Kanibolotska, Dr Lyudmyla and Skabara, Professor Peter and Findlay, Dr Neil and Kanibolotskyy, Dr Oleksandr and Hussien, Mrs Eman
• Authors: Hussien, E. J., Cameron, J., Findlay, N. J., Taylor, R. G.D., Johnson, M., Kanibolotska, L., Kanibolotsky, A. L., and Skabara, P. J.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Materials Horizons
• Publisher: Royal Society of Chemistry
• ISSN: 2051-6347
• ISSN (Online): 2051-6355
• Published Online: 31 August 2023
• Copyright Holders: Copyright © 2023 The Royal Society of Chemistry
• First Published: First published in Materials Horizons 10(11): 5087-5098
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
308252		rISC - the game of strategic molecular design for high efficiency OLEDs	Peter Skabara	Engineering and Physical Sciences Research Council (EPSRC)	EP/T022477/1	Chemistry
301327		`Hetero-print: A holistic approach to transfer-printing for heterogeneous integration in manufacturing	Peter Skabara	Engineering and Physical Sciences Research Council (EPSRC)	EP/R03480X/1	ENG - Electronics & Nanoscale Engineering