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65.1: Invited Paper : Amorphous Silicon TFT's with 100‐Year Lifetimes in a Clear Plastic Compatible Process for AMOLEDs
Author(s) -
Sturm James C.,
Hekmatshoar Bahman,
Cherenack Kuni,
Wagner Sigurd
Publication year - 2009
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1889/1.3256963
Subject(s) - thin film transistor , oled , brightness , materials science , optoelectronics , stack (abstract data type) , transparency (behavior) , amoled , amorphous solid , current (fluid) , silicon , electrical engineering , optics , computer science , physics , composite material , layer (electronics) , chemistry , engineering , active matrix , crystallography , computer security , programming language
Abstract We demonstrate critical elements of a‐Si technology on clear plastic for flexible AMOLED applications. First, we show that a‐Si TFT's with gate voltages under 5 V provide sufficient current for OLED pixel brightness of over 1000 cd/m 2 , with minimum geometries (W/L = 1)for 100 μm × 100 μm pixels. Critical to this result is a clear plastic with the combined properties of high transparency, glass transition temperature in excess of 300 °C, and low coefficient of thermal expansion. Second, we show that by engineering the a‐Si TFT stack, under the bias conditions for pixel operation, the “half‐life” of the TFT (defined as the time for the current to fall by 50% in DC operation) is 10 years for a 280 °C process on clear plastic, and at least 100 years for 300 °C. This is several orders of magnitude higher than that of common a‐Si TFT processes and in general larger than the lifetimes for the 50% decay of the luminescence of the OLED's themselves. Finally, we provide a framework demonstrating the tradeoff between drive current and TFT stability.