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A novel TFT‐OLED integration for OLED‐independent pixel programming in amorphous‐Si AMOLED pixels
Author(s) -
Hekmatshoar Bahman,
Kattamis Alex Z.,
Cherenack Kunigunde,
Wagner Sigurd,
Sturm James C.
Publication year - 2008
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1889/1.2835027
Subject(s) - amoled , oled , anode , pixel , materials science , thin film transistor , cathode , optoelectronics , active matrix , diode , voltage , computer science , electrical engineering , electrode , physics , nanotechnology , layer (electronics) , artificial intelligence , engineering , quantum mechanics
— The direct voltage programming of active‐matrix organic light‐emitting‐diode (AMOLED) pixels with n ‐channel amorphous‐Si (a‐Si) TFTs requires a contact between the driving TFT and the OLED cathode. Current processing constraints only permit connecting the driving TFT to the OLED anode. Here, a new “inverted” integration technique which makes the direct programming possible by connecting the driver n‐channel a‐Si TFT to the OLED cathode is demonstrated. As a result, the pixel drive current increases by an order of magnitude for the same data voltages and the pixel data voltage for turn‐on drops by several volts. In addition, the pixel drive current becomes independent of the OLED characteristics so that OLED aging does not affect the pixel current. Furthermore, the new integration technique is modified to allow substrate rotation during OLED evaporation to improve the pixel yield and uniformity. The new integration technique is important for realizing active‐matrix OLED displays with a‐Si technology and conventional bottom‐anode OLEDs.