AVS 46th International Symposium
    Flat Panel Displays Topical Conference Tuesday Sessions
       Session FP-TuM

Paper FP-TuM9
Photoisomerization and Photo-induced Alignment of Azobenzene Containing Dyes and Polymers in Ultrathin Films Fabricated by the Alternate Polyelectrolyte Deposition (APD): Application for LC Displays

Tuesday, October 26, 1999, 11:00 am, Room 604

Session: Novel Materials for Field Emission Displays and Technologies for Flexible Displays
Presenter: M.-K. Park, University of Alabama at Birmingham
Authors: R.C. Advincula, University of Alabama at Birmingham
M.-K. Park, University of Alabama at Birmingham
A. Baba, Niigata University, Japan
F. Kaneko, Niigata University, Japan
Correspondent: Click to Email
The incorporation of a photochromic moiety in polymers is very attractive due to the possibility of creating new light-sensitive materials and optical devices. Ultrathin films containing photoisomerizable moieties, e.g. azo dyes are excellent materials for inducing control in LC molecules (command layer effects), holographic surface relief gratings, optical storage media, nanoscale applications, etc. In this work we have employed the alternate polyelectrolyte deposition (APD) on solid substrates to fabricate ultrathin films containing photoactive azobenzene groups. We investigated the combination of polymer containing azobenzene dye (PAZO)/ polycation (PDADMAC or PDDA) system and the small molecule dye Direct Red 80/PDADMAC system at various layer thicknesses. The uniform layer by layer assembly of the films was determined by UV-vis spectroscopy, ellipsometry, X-ray reflectivity, QCM, AFM, and SPS. The complex photoisomerization behavior reveals the importance of layer ordering, azobenzene mobility, and aggregation states in determining the future utility of these films. We utilized polarized UV-light to induce photoisomerization and photo-alignment of these ultrathin films. Hybrid LC Cells reveal in-plane homogeneous alignment. Correlation was made on the effect of film formation parameters to the overall film quality and layer ordering. We observed high anisotropies dependent on the dye, layer preparation, thickness, etc. LC Cells made from 5 CB reveal read/write capabilities dependent on the thickness and irradiation parameters. Future possibilities for LC and Large area display device modifications are envisioned.