There are several types of OLED materials. The most basic division is between small-molecule OLEDs and large molecule ones (called Polymer OLEDs, or P-OLEDs). All commercial OLEDs today are SM-OLED based. P-OLEDs had great promise as they are naturally solution processable (and so can easily be used in InkJet printing and spin-coating fabrication methods) - but P-OLEDs are no longer popular as the performance was never up to par with SM-OLEDs. Intensive research is being performed to develop efficient solution-processable SM-OLEDs.
OLED emitter materials are classified as either fluorescent or phosphorescent. Fluorescent materials last longer but are much less efficient than phosphorescent materials. Currently most OLED displays use phosphorescent emitter materials - except for the blue color which is still fluorescent as the lifetime is still not good enough. Universal Display Corporation is pioneering PHOLED research, holding the basic patents in this area.
AMOLED vs PMOLED
These terms relate to the driving method of the OLED display. A PMOLED (Passive-Matrix OLED) is limited in size and resolution, but is cheaper and easier to make compared to an AMOLED (which uses an Active-Matrix). An AMOLED uses an active-matrix TFT array and storage capacitors. While these displays are more efficient and can be made large, they are also more complicated to make.
PMOLED displays are used in small devices or secondary displays while AMOLEDs are used in smartphones, tablets and TVs. Here's more information about the difference between PMOLED and AMOLED.
The are still many challenges facing the OLED industry. Here's a list of some of the major ones:
- Material lifetime and efficiency (especially of the blue material)
- Soluble OLED material performance and production processes
- Flexible OLED encapsulation
- Better backplane materials for flexible OLED
- Scaling of evaporation processes for direct-emission OLEDs beyond Gen-6
OLED technology today
The leading AMOLED producer today is Samsung, who's making around 300 million displays a year, and is still expanding production capacity - of mostly smartphone-sized flexible AMOLEDs. LG Display is the second largest producer, but LG is currently focused on WRGB (WOLED-CF) 55" to 77" OLED panels for OLED TVs. LG is producing around a million OLED TV panels each year, and expanding its capacity. LGD is also building flexible OLED production fabs.
Besides LG and Samsung, other players, including China's BOE, Visionox and Everdisplay are also starting to produce AMOLEDs, and other display makers such as Sharp and Japan Display aim to start producing OLEDs by 2018.
In the OLED lighting market, several companies (including as OLEDWorks/Philips, LG, OSRAM and Konica Minolta) are already shipping OLED panels, but production capacity is still low and prices are very high. OLED lighting today is mostly used in premium lighting fixtures and installations and massive investments in production capacity will have to be made for prices to drop and for OLEDs to be able to compete with LED lighting.