OLED displays-design

In this section, we provide a brief introduction to the field of display engineering and the human-factors issues which dictate display design. We then assess how OLEDs measure up to the criteria necessary to achieve a commercially successful display technology. But first, we take a short detour to lay out the language used by display engineers and to provide a means of translating from the scientific units that wc have used up to now. 

All these features above make AMOLED especially suitable for portable DVD players, digital cameras, portable TVs, and game players. The discussion in this section also suggests that the performance of a given OLED display can be maximized by proper design of display contents. 

All these calculations show that pentacene TFTs are feasible for active-matrix OLED display backplanes. For the Penn State/Kodak practical realization mentioned above, a 48 x 48 pixel bottom-emission display panel was designed on a 64 mm x 64 mm glass substrate. To obtain good yield, a design rule of 10 pm was used for the minimum feature size (line width or separation) for most structures on the test panel. The coarseness of this design rule is not related to the use of organic compounds, but rather to the simplicity of photolithographic processes. 

Dawson, R.M.A. et al.. The impact of the transient response of organic hght emitting diodes on the design of active matrix OLED displays, Int. Electron Devices Meeting, 875, 1998. 

Aerts, W.E., Verlaak, S., and Heremans, R, Design of an organic pixel addressing circuit for an active-matrix OLED display, IEEE Trans. Electron Devices, 49, 2124,... 

Several typical properties of PEDT PSS polymers that depend on the PEDT PSS ratio are summarized in Table 10.1. To meet requirements for conductivity, antistatic grades of PEDT PSS have relatively low PSS-contents, and therefore higher conductivity values. In contrast, PEDT PSS grades designed for hole-injection in polymer OLEDs have larger PSS contents, smaller particles (Figure 10.6), and lower conductivities. Specifically, PEDT PSS grades useful for passive matrix OLED displays have the lowest... 

Although the data here show we can achieve relatively uniform TFT performance, it is still not good enough for a display application, so a compensation circuit would be needed in the pixel design. Threshold voltage stability and uniformity, together, form perhaps the most risky feature of organic TFT backplanes for OLEDs. 

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