Processing and Low Voltage Switching of Organic Ferroelectric Phase-Separated Bistable Diodes

Authors

  • Mengyuan Li,

    Corresponding author
    1. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands
    • Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands.
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  • Natalie Stingelin,

    1. Department of Materials and Centre for Plastic Electronics, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
    2. FRIAS, School of Soft Matter Research, University of Freiburg, 79104 Freiburg, Germany
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  • Jasper J. Michels,

    1. Holst Centre, High Tech Campus 31, 5605 KN Eindhoven, The Netherlands
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  • Mark-Jan Spijkman,

    1. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands
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  • Kamal Asadi,

    1. Philips Research Laboratories, High Tech Campus 4, 5656AE, Eindhoven, The Netherlands
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  • Rene Beerends,

    1. Philips Research Laboratories, High Tech Campus 4, 5656AE, Eindhoven, The Netherlands
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  • Fabio Biscarini,

    1. CNR- ISMN, Institute for the Study of Nanostructured Materials, Via Gobetti 101, I-40129 Bologna, Italy
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  • Paul W. M. Blom,

    1. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands
    2. Holst Centre, High Tech Campus 31, 5605 KN Eindhoven, The Netherlands
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  • Dago M. de Leeuw

    Corresponding author
    1. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands
    2. Philips Research Laboratories, High Tech Campus 4, 5656AE, Eindhoven, The Netherlands
    • Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen The Netherlands.
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Abstract

The processing of solution-based binary blends of the ferroelectric random copolymer poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and the semiconducting polymer poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) applied by spin-coating and wire-bar coating is investigated. By systematic variation of blend composition, solvent, and deposition temperature it is shown that much smoother blend films can be obtained than reported thus far. At a low PFO:P(VDF-TrFE) ratio the blend film consists of disk-shaped PFO domains embedded in a P(VDF-TrFE) matrix, while an inverted structure is obtained in case the P(VDF-TrFE) is the minority component. The microstructure of the phase separated blend films is self-affine. From this observation and from the domain size distribution it is concluded that the phase separation occurs via spinodal decomposition, irrespectively of blend ratio. This is explained by the strong incompatibility of the two polymers expressed by the binary phase diagram, as constructed from thermal analysis data. Time resolved numerical simulation of the microstructure evolution during de-mixing qualitatively shows how an elevated deposition temperature has a smoothening effect as a result of the reduction of the repulsion between the blend components. The small roughness allowed the realization of bistable rectifying diodes that switch at low voltages with a yield of 100%. This indicates that memory characteristics can be tailored from the outset while processing parameters can be adjusted according to the phase behavior of the active components.

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