OLED stands for Organic Light-Emitting Diode, and OLED technology is an alternative to LCD and (the now deceased) plasma technologies in display production. An OLED consists of a thin film of organic carbon-based compounds sandwiched between two electrodes. When the compound receives an electric current, it emits light.
Because an OLED can generate its own light (as plasma could), it does not require the use of a backlighting or edge-lighting system the way LCD does. Therefore, it is better able to produce a true black (no electric current equals no light). An OLED display generally can't be as bright as an LCD, but it is capable of more light output than a plasma display. Beyond their potential to produce an amazing contrast ratio, OLED TVs can have a wider viewing angle than LCD, they can produce less motion blur, and they can be packaged in an even thinner, lighter cabinet that can even be flexible.
OLED technology is currently used in many personal electronic devices, like cell phones, portable audio players, etc. In the TV realm, Sony was the first company to introduce an OLED monitor back in 2008: the 11-inch XEL-1. We did not see a large-screen OLED TV until 2013, when Samsung and LG both brought 55-inch panels to market. You can read our review of the first Samsung OLED TV here. Samsung and LG use different approaches in creating an OLED pixel. Samsung used RGB OLED, in which each pixel contains a red, green, and blue sub-pixel laid directly on the display panel, which eliminates the need for color filters. LG's approach is called White OLED (or WOLED), which uses RGB color layers that are applied to the organic layer and act as color filters for the light being emitted. In addition to red, green, and blue color filters within each pixel, LG adds a clear filter that allows white light to pass through, which is designed to improve brightness and efficiency.
TV manufacturers encountered a number of stumbling blocks in trying to bring large-screen OLED TVs to market--namely, it is expensive to produce at large screen sizes, and the yield rate (the number of defect-free models that can be sold) was low--causing companies like Samsung, Sony, and Panasonic to abandon or at least postpone their OLED TV development efforts. Sony and Samsung never introduced new OLED TVs to market after the ones described above. LG has remained committed to OLED and has brought many models to market, in sizes up to 78 inches. You can view the company's complete lineup here. Panasonic has also continued its OLED development, although the company has yet to introduce an OLED TV to the U.S. market.
Like LCD, OLED is well suited to accommodate new video technologies like 4K resolution, a wider color gamut, and High Dynamic Range capability. The newest OLED TVs from LG support all of these technologies.
OLED Is Alive and Well...and Coming to a Store Near You, September 2013
Sony Drops OLED, June 2014
What Quantum Dots Mean to Your Next UHD TV, February 2015
High Hopes for High Dynamic Range (HDR) Video, February 2015
LG Trying to Set Up OLED Alliance, March 2015
Panasonic Announces THX-Certified 4K OLED TV at IFA, September 2015