Ultraviolet light induced changes in polyimide liquid-crystal alignment films
- Center for Display Technology and Manufacturing, The University of Michigan, Ann Arbor, Michigan 48109 (United States)
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87185-1349 (United States)
Ultraviolet light induced changes in polyimide liquid-crystal alignment films were investigated. Infrared, UV-visible, x-ray photoelectron spectroscopy, and electron-spin-resonance measure- ments indicated that bond breaking and subsequent oxidation reactions occur in polyimide films (SE7210, OCG284, DuPont 2555 and 2540) during the broadband UV illumination in air. Mechanical rubbing has no effect on the optical and magnetic properties but it causes the removal of the UV-exposed film. Capacitance{endash}voltage measurements indicate that there is a slight decrease in dielectric constant and creation of net negative charges in the film after UV exposure. Sur- face tension of polyimide films before and after UV illumination and changes in the pretilt angle of the polyimide surface following UV exposure have also been studied. The decrease in pretilt angle following UV illumination is attributed to an increase in surface tension. Our results indicate that a simple UV technique can be used to achieve domain divided liquid-crystal pixel electrode design with improved viewing characteristics. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 392679
- Journal Information:
- Journal of Applied Physics, Vol. 80, Issue 9; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
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