OLED panels are created from organic (carbon based) materials that emanate light when they’re connected to electricity. Since OLEDs do not require a backlight and filters, in contrast to LCD displays, they are more powerful, easier to manufacture, and much thinner, they can even be made flexible and rollable ! OLEDs have a great image aspect – shiny colors, deep contrast, fast response rate and expended viewing angles. OLEDs can also be used to make OLED lighting – thin, efficient and with only resisted materials.
OLED materials have been discovered back in 1960, but only in the past 20 years or so have researchers started to actually work on the technology. The very first brevet was labeled by Kodak in 1987, this device used a novel two-layer structure with separate hole transporting and electron transporting layers such that recombination and light emission occurred in the middle of the organic layer; this resulted in a reduction in operating voltage and improvements in efficiency.
How do OLEDs work?
The essential component in an OLED display is the OLED emitter – an organic (carbon-based) material that emits light when electricity is applied. The basic structure of an OLED is an emissive layer sandwiched between a cathode (which injects electrons) and an anode (which removes electrons). Modern OLED devices use many more layers in order to make them more efficient and durable, but the basic functionality remains the same.
Transparent OLEDs use transparent or semi-transparent contacts on both sides of the device to create displays that can be made to be both top and bottom emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view displays in bright sunlight.This technology can be used in Head-up displays (used in the air force ), smart windows or augmented reality applications and has been used (with a black light absorbing backing) on some Samsung Galaxy phones such as the S4 Mini verified by Andre de-Guerin around June 2016.
Lower cost in the future
OLEDs can be printed onto any suitable substrate by an inkjet printer or even by screen printing, theoretically making them more economical to produce than LCD or plasma displays. However, fabrication of the OLED substrate is currently more costly than that of a TFT LCD, until mass production methods lower costs through scalability. Roll-to-roll vapor-deposition methods for organic devices do allow mass production of thousands of devices per minute for minimal cost
How an OLED panel is made
An OLED panel itself is made from a substrate, backplane (electronics – the driver), frontplane (the organic materials and electrodes as explained above) and an encapsulation layer. OLEDs are very receptive to air and moisture and so the encapsulation layer is critical.
The substrate and backplane of an OLED display are comparable to those of an LCD display, but the front plane deposition is unique to OLEDs. There are a lot of manners to drop and pattern the organic layers. Presently most OLED displays are manufactured using vacuum evaporation, using a Shadow Mask (FMM, Fine Metal Mask) to pattern. This is a relatively plain approach but it is inefficient (a lot of material is wasted) and very difficult to rate to large substrates.
Some OLED elements are soluble, and these can be deposited using printing methods – mostly ink-jet printing. This technology is not commercialized yet, but OLED makers hope that ink-jet printing may be a scalable, profitable and low-cost manner to deposit OLEDs.
Lightweight and flexible plastic substrates
OLED displays can be fabricated on flexible plastic substrates, leading to the possible fabrication of flexible and ultra thin displays for other new applications, such as roll-up displays embedded in fabrics or clothing. If a substrate like polyethylene terephthalate (PET) can be used, the displays may be produced inexpensively. Furthermore, plastic substrates are shatter-resistant, unlike the glass displays used in LCD devices.
Better picture quality
OLEDs enable a greater artificial contrast ratio (both dynamic and static) and wider viewing angle compared to LCDs, because OLED pixels emit light directly. Furthermore, OLED pixel colors appear precise and unshifted, even as the viewing angle approaches 90° from the normal.
Better power efficiency and thickness
LCDs filter the light emitted from a backlight, allowing a limited fraction of light through. Thus, they cannot show true black. However, an inactive OLED element does not produce light or consume power, allowing true blacks. Removing the backlight also makes OLEDs clearer because some substrates are not needed.
OLEDs also have a much faster response time than an LCD. Using response time compensation technologies, the fastest modern LCDs can reach response times as low as 1 ms for their fastest color transition, and are capable of refresh frequencies as high as 144 Hz. Due to their extremely fast response time, OLED displays can also be easily designed to be strobed, creating an effect similar to CRT flicker in order to avoid the sample-and-hold behavior seen on both LCDs and some OLED displays, which creates the perception of motion blur.