1. Technical Field
The disclosed embodiments relate to flat panel display devices, and in particular relates to a method of fabricating a pixel structure for an organic light-emitting display (OLED).
2. Description of the Related Art
Due to thin profiles, light weights and low power consumption provided by flat panel display (FPD) devices, related problems associated with cathode ray tube (CRT) display technology have been solved, and FDP devices are now widely applied in electronic devices, such as laptop computers, personal digital assistant (PDA), e-books (electronic books), projectors, and mobile phones. Generally, flat panel display devices include active matrix liquid crystal display (AMLCD) devices and active matrix organic light-emitting display (AMOLED) devices. Unlike the active matrix liquid crystal display devices, the active matrix organic light-emitting display devices are self-emissive devices using organic material without the requirement of a backlight module. Therefore, the manufacturing process is simplified and the thickness of flat panel display devices is further reduced. Typically, the pixel structure of active matrix organic light-emitting display devices comprises a thin film transistor (TFT) array substrate and a plurality of organic light-emitting diodes disposed thereon. Each organic light-emitting diode includes an upper electrode (a cathode or anode), a lower electrode (an anode or cathode), and an organic light-emitting layer disposed between the two electrodes.
In active matrix organic light-emitting display devices, an electrode contact hole is typically formed outside of the display region (or active region) such that the upper electrode of the organic light-emitting diode and the electronic devices on the TFT array substrate form a loop. However, the voltage drop (IR drop) effect results in a brightness difference between the central pixel region and the peripheral pixel region in the display region (i.e., poor brightness uniformity). In top emission light-emitting display devices, metal (such as calcium, magnesium, lithium, silver and alloys thereof) or the combination with transparent conductive oxide (such as indium tin oxide, indium zinc oxide, aluminum zinc oxide, zinc oxide) with resistance higher than metal are usually used as the upper electrode of the organic light-emitting diode, therefore the IR drop effect is more significant. Moreover, the problem of poor brightness uniformity is more serious for large-sized organic light-emitting display applications.
Therefore, there is a need to develop an improved method of fabricating a pixel structure for an organic light-emitting display (OLED), mitigating or eliminating the aforementioned problems.