A polysilicon transistor based active matrix organic light emitting diode (AMOLED) pixel with high pixel to pixel luminance uniformity is reported. The new pixel powers the OLEDS with small constant currents to ensure consistent brightness and extended life. Excellent pixel to pixel current drive uniformity is obtained despite the threshold voltage variation inherent in polysilicon transistors. considerations in the design for high information content displays are discussed.
The design of an active matrix organic light emitting diode (AMOLED) display using a polysilicon thin film transistor pixel is described. Characteristics of the OLED response in the low current regime are described and their impact on the design of integrated driver circuitry is discussed. Integrated data and select scanners which generate the signals necessary for data capture and pixel calibration are presented.
A key requirement for fabrication of organic light emitting diode (OLED) displays is uniform film deposition over large areas because of the sensitivity of emission color and efficiency on film thickness. Conventional deposition using point sources is unattractive because of the requirement of a large source to substrate separation, usually with substrate rotation, to achieve acceptable thin film uniformity. By translating a novel extended linear evaporation source in a single direction, film nonuniformity of less than 5% has been demonstrated over a 300 mm x 400 mm substrate with a source to substrate separation of 100 mm.OLEDs with all organic layers deposited using linear sources have been determined to operate identically to devices fabricated using conventional point sources. The performance of doped and undoped devices as well as the advantages of linear source deposition over conventional deposition techniques will be described.
A nonmetallic connector has been developed for high‐efficiency tandem white architecture. Forming the “N” type layer using NDN‐26 doped into NET‐18 and inserting an organometallic thin layer between the “N” and “P” layers results in a high‐performance connector. An efficiency of 33 cd/A has been achieved at 6.7 V, 1000 cd/m2 and 10000K color temperature in a fluorescent based tandem emitter. This >15% EQE device also demonstrates a half‐life of ∼80,000 h at 1000 cd/m2.
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