(Organic Light Emitting Device, Organic Light Emitting Diode) A display technology that offers bright, colorful images with a wide viewing angle, low power, high contrast ratio and fast response time for sports and action movies. OLEDs also have great potential for general lighting.
Passive matrix OLEDs began to appear in small-screen devices such as cellphones and MP3 players in the late 1990s and active matrix OLEDs followed starting in 2003 (see AMOLED). In 2007, Sony introduced the first active matrix OLED TV, and along with Toshiba and Samsung, announced plans for larger OLED TVs. In 2009, OQO introduced the first active matrix OLED screen in a handheld Windows computer.
PHOLED - A Quantum Leap
Phosphorescent OLEDs (PHOLEDs) from Universal Display Corporation (UDC), Trenton, NJ (www.universaldisplay.com) consume less power than LCDs, enabling OLED to eventually become the dominant display technology of the 21st century (for more details, see PHOLED).
Showing off its intense colors, Sony captivated Japanese audiences in 2007 with its first OLED TV. Stateside a year later, it came with a whopping $2499 price tag for an 11" TV. The thin screen was highly accentuated by encasing it apart from the tuner circuits. (Image courtesy of Sony Corporation.)
In 2009, the 5" display in this Windows handheld was the first OLED screen in a portable computer. (Image courtesy of OQO, Inc., www.oqo.com)
Monolithic Devices
OLED screens consist of a series of organic layers between two electrical contacts (electrodes). Similar to LEDs, when electrons and holes combine in the organic layer, they emit photons.
Unlike LCD displays, which are made of separate layers, OLEDs are monolithic: each layer is deposited on the other, creating a single unit. Commonly constructed on glass, OLEDs can also be fabricated on plastic and other flexible films, such as the Flexible OLED (FOLED) from Universal Display (www.universaldisplay.com).
Extremely Versatile
OLEDs can be transparent, enabling them to function in heads-up displays and even as window shades that react to sunlight. Unlike LCDs, OLEDs do not require backlights, and screens can be made ultra thin. OLED's color, speed, thinness, transparency and flexibility (see roll-up illustration below) make it a very versatile display technology. See AMOLED, TOLED, WOLED and LED.
On regular OLEDs, the top cathode layer reflects light back. On transparent OLEDs, (TOLEDs), the cathode is transparent. OLEDs can be made using small-molecular weight organic materials (SM-OLEDs) or polymer-based materials (PLEDs, LEPs). (Illustration courtesy of Universal Display Corporation, www.universaldisplay.com)
Although seemingly far fetched, flexible OLED screens like this are expected within a few years. (Image courtesy of Universal Display Corporation, www.universaldisplay.com)
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