One-dimensional confinement in crystallization of P(VDF-TrFE) thin films with transfer-printed metal electrode

The crystallization of thin polymer film depends on surface/interface properties, due to the fact that molecular chain motion is affected by the presence of the surface. In this work, we measured the ferroelectric properties, crystallinity, chain conformation and surface morphologies of one-dimensionally confined P(VDF-TrFE) thin films using transfer-printed Au film, annealed at elevated temperatures, from just below melting temperature up to 200 °C. Crystallization at low temperature, i.e., below melting temperature, the confinement effect has been found to be negligible. At high temperatures, however, confined crystallization has led to superior ferroelectric properties, compared to samples annealed without confinement. These observations have led to two- or three-layer model for those crystallized thin films with or without confinement, respectively. Further, the transfer-printing of metal as a confining surface has been found to be beneficial, compared to vacuum evaporation, due to deposition-induced damages on organic polymer. This confinement-induced retention of ferroelectricity in P(VDF-TrFE) thin films above its melting temperature can extend processing temperature in organic devices using the ferroelectric polymer, such as non-volatile organic memory devices.

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