Enabling Technology for Thin Film Displays
Abstract
This program has laid the foundations for rugged, flexible, bendable high performance thin-film transistor (TFT) backplanes for display and sensor/detector array applications and has further developed patterned organic layers for color OLED's using both wet and dry processes. Innovations have been made in transistor materials and processing, substrate treatments and processing, and systems integration. Six backplane TFT technologies have been developed for flexible substrates: (1) amorphous silicon TFTs on steel foils, which yields TFT structures which are rugged and dimensionally stable; (2) polycrystalline silicon TFT complementary metal oxide on silicon (CMOS) on steel foils, which takes advantage of the high temperature tolerance of steel; (3) high performance polycrystalline silicon (p-Si) TFT CMOS using a separation approach which allows full high-temperature processing and yields mobilities for holes and electrons over 300 square centimeters/volt-second; (4) amorphous silicon (a-Si) TFTs on plastic (Kapton) foil using an amorphous silicon process optimized for 150 deg C, (5) nanocrystalline silicon (n-Si) TFTs using processing that is adaptable to direct deposition on plastic foil substrates, and (6) polymeric TFTs fully compatible with flexible substrates and demonstrating record mobilities. In the OLED work, both wet and dry patterning for OLED processing have been found to be compatible with roll-roll processing and not to require vacuum. Wet processes (e.g., ink jet printing) have been found to depend critically on the final printed profiles which result from the drying process of the liquid. By developing a solvent-assisted diffusion process for organic molecules in polymers, which can temporarily depress glass transition temperatures by over 100 deg C, a practical large-area dry-patterning process has been developed for patterning color OLED's.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2002
- Accession Number
- ADA405636
Entities
People
- James C. Sturn
- Sigurd Wagner
- Steven J. Fonash
- Thomas N. Jackson
Organizations
- Pennsylvania State University