Organic Light Emitting Diode technology is used to make displays for video, computer screens, mobile devices, and more. Light is generated when a voltage is applied across an emissive electroluminescent layer of an organic (containing carbon) semiconductor compound via two electrode layers. The brightness of the light from each diode is varied according to the video input – unlike ‘LED’ screens that are predominant in the current screen market. Here the LEDs provide a white backlight behind an LCD (liquid crystal display) that works as a red, green and blue light filter for each pixel that is controlled by the input image (video, etc).
The OLED technology offers a number of benefits over LED screen technology. As there is no backlight, when the OLEDs are switched off there is no light emitted. Black really looks black, and the screens are specified with a very high contrast ratio. They also offer a faster response time, wider viewing angles and larger color gamuts. As a result the images look very good and they they are often used as monitors. As it is easy to put the OLEDs very close together it is possible to make very small screens that deliver full resolution images – useful for viewfinders, handheld devices, phone, etc. An OLED screen’s power consumption is less than equivalent LED screen as almost all the light generated is visible, none absorbed in filters. The screens can be very thin. An early 50-inch consumer model was boasting 6mm thickness. The screens can be bent, and some manufacturers are offering curved screens. Perhaps OLEDs may be used to make a roll-up screen.
On the downside, OLED screens are still offered at a substantial price premium over LED versions. Also it is said that the life expectancy of OLED screens is considerably less than that of LEDs, mainly due to the relatively short life of the blue OLEDs. Work continues to improve that area.
OLED screens have been produced for a number of years but only recently have been widely available in the consumer market.