you happened to pick my post-doc research area so…
OLEDS come in two types - sublimed small molecules and solution based polymer types. The first are hard to make quickly, so not so good for large scale manufacture. The japanese have gone down this path mainly. The second is being developed rapidly by a number of companies.
However, LCDs have had a huge head start. To make a factory making large scale displays will probably cost up to a billion, so everything must be perfect. Several things holding back OLEDs
operating lifetimes: in practice not always good enough for a display (20,000 hours needed). But for cell-phones or other consumer products it is fine. Currently can get reliably between 1000-10,000 hours depending on colour and type.
Addressing: To get a large display you need active matrix addressing, e.g silicon backplane. Not cheap on a large area, and back-planes have so far only been optimised for LCD displays (e.g. voltage driven) rather than OLEDS (current driven). The OLEDs also drift a little during operation, so need compensation circuitry. All quite possible, but that is another factory again to make the backplane.
Efficiency. At the moment a little bit better, but not 6 X as good as LCDs. The problem is that the OLEDs have lots of small losses that also add up, e.g. higher than wanted voltage operation, less than 100% fluorescence efficiency, less than 100% charge capture, less than 100% colour purity. The main advantage of OLEDs is their wide viewing angle and much faster refresh rate. They should also be be more efficient, but only in an ideal world. See CDTs website for more details www.cdtltd.co.uk/
OLEDs will have to battle it out against ferroelectric LCDs (fast and good viewing angle, known technology), plasma displays, field effect displays etc. No one is going to commit a billion pounds yet, so we will have to wait a few years until they prove themselves, and gradually expand their market. Of course by then other technologies may have come through. e.g see http://www.screentechnology.com/tech/
The hype about flexible OLEDs on clothing etc may be a long way off. These displays are very very sensitive to oxygen and water during operation and need outstanding encapsulation. they are also very sensitive to variations in thickness, and so are not suited to coating on rough surfaces. On the other hand, WRONZ ( http://www.wronz.org.nz/wronz-main/index.shtm )has developed an inorganic variety that can go through the wash! Sorry cant find a direct cite, but I have held it in my hand so it must be true.