Mixed Conduction in an N‐Type Organic Semiconductor in the Absence of Hydrophilic Side‐Chains
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- Biological and Environmental Science and Engineering Division Organic Bioelectronics Laboratory King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia
- Department of Chemistry Northwestern University Evanston IL 60208 USA
- Physical Science and Engineering Division KAUST Solar Center (KSC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia
- Physical Science and Engineering Division KAUST Solar Center (KSC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia, Department of Chemistry Chemistry Research Laboratory University of Oxford Oxford OX1 3TA UK
- Department of Chemistry Northwestern University Evanston IL 60208 USA, Simpson Querrey Institute Northwestern University Chicago IL 60611 USA
Abstract Organic electrochemical transistors (OECTs) are the building blocks of biosensors, neuromorphic devices, and complementary circuits. One rule in the materials design for OECTs is the inclusion of a hydrophilic component in the chemical structure to enable ion transport in the film. Here, it is shown that the ladder‐type, side‐chain free polymer poly(benzimidazobenzophenanthroline) (BBL) performs significantly better in OECTs than the donor–acceptor type copolymer bearing hydrophilic ethylene glycol side chains (P‐90). A combination of electrochemical techniques reveals that BBL exhibits a more efficient ion‐to‐electron coupling and higher OECT mobility than P‐90. In situ atomic force microscopy scans evidence that BBL, which swells negligibly in electrolytes, undergoes a drastic and permanent change in morphology upon electrochemical doping. In contrast, P‐90 substantially swells when immersed in electrolytes and shows moderate morphology changes induced by dopant ions. Ex situ grazing incidence wide‐angle X‐ray scattering suggests that the particular packing of BBL crystallites is minimally affected after doping, in contrast to P‐90. BBL's ability to show exceptional mixed transport is due to the crystallites’ connectivity, which resists water uptake. This side chain‐free route for the design of mixed conductors could bring the n‐type OECT performance closer to the bar set by their p‐type counterparts.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1784446
- Journal Information:
- Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 31 Journal Issue: 21; ISSN 1616-301X
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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