OLED, short for Organic Light-Emitting Diode, is a next-generation technology for lighting and electronic displays. OLED is primarily a light source but the term is also used for the associated display technology. The term organic in the abbreviation refers to the fact that the materials used are based on carbon instead of the much more common silicon.
The technology is becoming increasingly popular in televisions, but is already widely used in smartphones. In phones the technology is often called AMOLED (where AM is short for Active Matrix).
An OLED screen consists of organic material that emits light when it is tensioned. Depending on composition, the material may give different colors. The colors are then combined into several pixels to form a screen.
Each pixel is its own light source, and therefore an OLED screen does not require any backlighting. It also allows each pixel to be turned off to achieve deep blacks and a theoretically infinite contrast ration. Unlike LCD monitors, OLED panels have no problems with local dimming, clouding and bleeding. OLED displays also offer extremely good viewing angles and color reproduction.
As they also consist of fewer layers than LCDs, they can be extremely thin, even foldable.
The most common OLED technology, though unusual for televisions, is direct emission. It is used for small OLED screens. Here each pixel is made up of three sub-pixels (RGB), similar to LCD technology. The difference is that each sub pixel is individually lit and so eliminated the need for backlighting. The pixel is does not have to be treated by a filter to show color, rather it gives off the right color from the beginning.
One of the manufacturers who have used the technology is Samsung, for its mobile screens primarily, but attempts have been made to incorporate it into television production. However, the problem with the technology is that it is difficult to scale up to big displays, and as of this writing Samsung has given up on producing large OLEDs.
LG is currently the only manufacturer of OLED panels suited for televisions. While other manufacturers such as Sony and Philips also make OLED TVs, they use panels from LG, which uses a technology called WRGB. Each pixel consists of four sub-pixels. The sub-pixels are then colored by a color filter to white, red, green and blue, and are in turn combined into a pixel in the desired color.
The advantage of this technology is that it is more cost-efficient to manufacture, especially for large displays. Unfortunately, the technology is not as bright or energy-efficient as Direct Emission, but the color spectrum and viewing angles are still very good. WRGB technology could also be combined with quantum dots, which in theory could provide almost perfect colors.
OLED vs LED and other LCD Displays
The keyword in the OLED acronym is organic, and this makes it a wholly different light-emitting diode than other LEDs, with the light-emitting layer is comprised of a thin film of organic (carbon-based) compounds. This electroluminescent layer is arranged in rows and columns on a display matrix, and directly emits light in different colors.
While OLEDs can be used as general purpose light sources, they are thus far more widely used in different types of displays, including computer monitors, television screens and smartphones.
One of the major benefits with OLED display technology compared to traditional LED light sources is that OLED diodes can produce both light and colors, so they don’t require separate backlighting. This results in a lower power draw, which is a particularly significant advantage when powered from a battery, meaning that they can operate longer on a single charge.
What are the advantages of OLED technology?
- Vibrant colors
- High contrast (no light leak)
- Excellent grayscale
- Broad viewing angles
- Full-motion video
- Wide viewing angles from all directions
- A wide range of pixel sizes
- Low power consumption
- Low operating voltages
- Wide operating temperature range
- Long operating lifetime
- Thin and lightweight form factor
- Displays can be flexible
- May be translucent
What about the disadvantages?
The main disadvantage of OLED displays is that large panels are very expensive, but we expect prices to decline as technology matures.
There is also problem of a limited life span. The organic, electroluminescent material used will not last forever. It is expected that a standard OLED display can be used for more than 20,000 hours, which is equivalent to five hours a day for eleven years. But because OLED technology is recent it is difficult to evaluate what the actual figures will look like.
Since each pixel is its own light source, it will be evident when one of the pixels goes out. Even if only 1 out of 10,000 pixels is broken, over 200 pixels will effectively stop shining on a 1080p display. In addition, the colors have a varying life span, where the color blue has the shortest life time.