Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.
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We gratefully acknowledge financial support from Innovate UK (PORSCHED project) and the Engineering and Physical Sciences Research Council though a Programme Grant (EP/M005141/1). I.N. acknowledges studentship support from FlexEnable Ltd. K.B. gratefully acknowledges financial support from the Deutsche Forschungsgemeinschaft (BR 4869/1-1). A.S. would like to acknowledge support from the India-UK APEX project. B.R., M.K.R. and J.-L.B. acknowledge the financial support from King Abdullah University of Science and Technology (KAUST), the KAUST Competitive Research Grant program, and the Office of Naval Research Global (Award N62909-15-1-2003); they also acknowledge the IT Research Computing Team and Supercomputing Laboratory at KAUST for providing computational and storage resources.
Intellectual property on the reported technique has been licensed by the University of Cambridge to FlexEnable Ltd.
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Nikolka, M., Nasrallah, I., Rose, B. et al. High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives. Nature Mater 16, 356–362 (2017). https://doi.org/10.1038/nmat4785
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