to large television displays or larger. They are called "plasma" displays because the technology uses small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps. LCD Liquid-crystal-display televisions (LCD TV) are television sets that use LCD display technology to produce images. LCD televisions are much thinner and lighter than cathode-ray tube (CRTs) of similar display size, and are available in much larger sizes (e.g., 90-inch diagonal). When manufacturing costs fell, this combination of features made LCDs practical for television receivers. LCDs come in two types: those using cold cathode fluorescent lamps, simply called LCDs and those using LED as backlight called as LEDs. In 2007, LCD television sets surpassed sales of CRT-based television sets worldwide for the first time, and their sales figures relative to other technologies accelerated. LCD television sets have quickly displaced the only major competitors in the large-screen market, the Plasma display panel and rear-projection television. In mid 2010s LCDs especially LEDs became, by far, the most widely produced and sold television display type. LCDs also have disadvantages. Other technologies address these weaknesses, including OLEDs, FED and SED, but none of these have entered widespread production. OLED An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound which emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes. Generally, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens. It is also used for computer monitors, portable systems such as mobile phones, handheld game consoles and PDAs. There are two main groups of OLED: those based on small molecules and those employing polymers. Adding mobile ions to an OLED creates a light-emitting electrochemical cell or LEC, which has a slightly different mode of operation. OLED displays can use either passive-matrix (PMOLED) or active-matrix (AMOLED) addressing schemes. Active-matrix OLEDs require a thin-film transistor backplane to switch each individual pixel on or off, but allow for higher resolution and larger display sizes. An OLED display works without a backlight. Thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD). In low ambient light conditions such as a dark room an OLED screen can achieve a higher contrast ratio than an