Surface anchoring effect on the morphology and performance of polymer-dispersed liquid crystal

Yi-Hsin Lin*, Hongwen Ren, Yung Hsun Wu, Xiao Liang, Shin Tson Wu

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

16 Scopus citations

Abstract

Surface effects on the phase separation dynamics, morphologies, and electro-optic properties of thin polymer-dispersed liquid crystal (PDLC) cells are investigated. Four types of surface alignment layers were studied: ITO only, Polyimide (PI) without rubbing, homogeneous cell, and 90° twisted nematic (TN) cell. The ITO-only and non-rubbed PI cells do not provide enough anchoring force to prevent LC droplets flow and coalesce. As a result, the droplets are larger and less uniform. For the homogeneous and TN cells with sufficiently high anchoring energy, almost all the nucleated LC droplets grow at a fixed position during phase separation. The appearance of the coalescence is not obvious and the formed LC droplets are relatively uniform. For the rubbed cells with polar anchoring energy >2x 10 -4 J/m 2, the droplet size is smaller and more uniform than those in the conventional PDLC cell. The phase separation dynamics determine the final composite morphology which affects the electro-optic properties of a PDLC device. The morphologies in the homogeneous and TN cells are similar, but the TN cell is polarization independent while the homogeneous cell is polarization dependent. Moreover, the TN PDLC cell exhibits a higher contrast ratio. The light shutter made of TN PDLC shows no haze and 5-10 ms response time.

Original languageEnglish
Article number11
Pages (from-to)74-82
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5741
DOIs
StatePublished - 22 Aug 2005
EventEmerging Liquid Crystal Technologies - San Jose, CA, United States
Duration: 25 Jan 200527 Jan 2005

Keywords

  • High contrast ratio
  • Morphologies
  • Polymer-dispersed liquid crystal
  • Surface anchoring effect

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