Processing and low voltage switching of organic ferroelectric phase-separated bistable diodes

Mengyuan Li, Natalie Stingelin, Jasper J. Michels, Mark Jan Spijkman, Kamal Asadi, Rene Beerends, Fabio Biscarini, Paul W.M. Blom, Dago M. De Leeuw

Research output: Contribution to journalArticle

39 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2750-2757
Number of pages8
JournalAdvanced Functional Materials
Volume22
Issue number13
DOIs
Publication statusPublished - 10 Jul 2012

Keywords

  • bistable diodes
  • ferroelectric blends
  • ferroelectricity
  • non-volatile memory
  • self-affine surfaces
  • spinodal decomposition

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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