Display technology, flat panel

In display technology flat-panel-displays are today in production. Advanced products such as large screen plasma displays and miniature thin-film-transistor-liquid-crystal display (LCDs) are commercially available. Recently the quality and reliablility have improved considerably. So, for instance, the conical viewing angle of liquid crystal displays has been extended to nearly 160° with in-plane-switching active-matrix LCDs. 

The paper is oiganized to describe, first, the materials that have been used in OLEDs, then the device structures that have been evaluated. After a description of the methods used to characterize and evaluate materials and devices, we summarize the current stale of understanding of the physics of device operation, followed by a discussion of the mechanisms which lead to degradation and failure. Finally, we present the issues that must be addressed to develop a viable flat-panel display technology using OLEDs. Space and schedule prevent a comprehensive review of the vast literature in this rapidly moving field. We have tried to present... 

Mentley, D. E. 2002. State of flat-panel display technology and future trends. Proc. IEEE 90 453 159. 

Over the last 50 years, remarkable improvements in the performance of vapor-deposited OLEDs have been made. Operating voltages have been decreased from a few kilovolts to a few volts, at the same time efficiencies are now approaching 100 lm/W. These improvements in device performance have made commercial displays based on vapor-deposited OLEDs viable. This technology is now poised to compete with liquid crystal displays (LCDs) in an expanding flat panel display marketplace. 

One of the most obvious markets for thin-film vapor-deposited organic materials is in flat panel displays [123], a market currently dominated by LCDs. Over the last two decades, a great improvement in the lifetime and efficiency of OLEDs have been achieved. OLED displays can already be found in simple applications such as automobile stereos, mobile phones, and digital cameras. However, to exploit the advantages of the technology fully, it is necessary to pattern the OLEDs to form monochrome, or more preferentially, full-color displays. This section will consider the difficulties involved in addressing such displays (either passively or actively) and the variety of patterning methods that can be used to produce full-color displays. 

The biggest growth area in LC based displays has been in full-colour flat panel displays for use in conjunction with computers, especially portable machines. The two major technologies used in this area, as stated above, are STN-LCDs and AMTFT-LCDs, with the latter, as their prodnction costs diminished, taking the major share of the market. This is becanse they exhibit a more uniform, wide viewing angle and superior display brighmess. ... 

Colloids hold a considerable potential for applications that are unusual in the classical sense. Most of us are familiar with imaging devices such as the picture tube in a television set. These tubes are bulky and consume large amounts of electrical power. There is, therefore, a large incentive to develop compact imaging devices, known as flat-panel devices, that are easily portable and have lower power requirements. (Displays based on liquid crystal technology fall in this class.)... 

Organic light-emitting devices (OLEDs) are one of several technologies competing for the market for next-generation emissive flat panel displays. It is the one most likely to triumph over field emission displays (basically CRT technology in miniature) and plasma display panels. 

---