Homogeneous liquid crystal alignment on poly(vinylidene fluoride-trifluoroethylene) films subjected to ion-beam irradiation

Abstract

We demonstrate homogeneous and uniform liquid crystal (LC) alignment on poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] films using ion-beam (IB) irradiation and a performance improvement of twisted nematic (TN) cells using IB-irradiated PVDF-TrFE films. Spontaneous ferroelectricity of the PVDF-TrFE films was modified by IB irradiation, which affected the LC alignment properties. The variation in the pre-tilt angles of the LC molecules on the IB-irradiated PVDF films is attributed to surface reformation, including defluorination and oxidation because the pre-tilt angles of LC molecules can be controlled by adjusting the fluorine content. The results of contact angle measurements supported this phenomenon. A 58% reduction in the switching voltage was observed for TN cells, indicating that the IB-irradiated PVDF-TrFE films are a promising candidate for use as an alignment layer.

Static and dynamic electro-optical properties of liquid crystals mediated by ferroelectric polymer films

“… 27–29 Alignment and electro-optical properties of twisted nematics sandwiched between PVDF-based films are reported in recent papers. 30,31 An experimental evidence of the strong impact of the remnant polarization of PVDF-based polymer on the alignment of liquid crystals has been shown for polymer dispersed liquid crystals (PDLC). 32,33 Results presented in Holländer et al 33 were obtained using cyanobiphenyl-based liquid crystals characterized by a relatively high concentration of residual ions.…”

Effect of Poly(vinylidene fluoride-trifluoroethylene) Film Concentration and Alignment Method upon Liquid Crystal Alignment

“…[19][20][21] Shah et al demonstrated the capability of PVDF-TrFE copolymers to serve as LC alignment layers when treated with corona poling. 21 In addition, we demonstrated that uniform LC alignment can be achieved on the PVDF-TrFE films fabricated at a low temperature of 135 • C. 22 To align LC molecules on the LC alignment film surface during LCD fabrication, rubbing methods are conventionally used. However, there are some disadvantages arising from mechanical contact with the alignment layers, including the accumulation of electrostatic charge and the generation of fine dust, which degrade LCD quality.…”