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What are OLEDs?  Organic Light Emitting Diodes are a different type of solid-state lighting source.  First developed by Eastman Kodak in 1985, an OLED device is typically formed in a sheet with emissive organic layer(s) sandwiched between a cathode and anode and deposited on a substrate.  The substrate can be rigid such as glass or metal or flexible using a polymer plastic.  The number of emissive layers depends on the desired light output of the device.

Does the light output differ between OLEDs and LEDs?  LEDs are point sources with very small (typically 1mm2) light emitting areas.  OLEDs are area sources with light emitted across the entire surface of the sheet.  In the case of transparent substrates, that light is emitted from both sides of the OLED device.  OLED Description

How do OLEDs produce light?  Like their LED counterparts, OLEDs produce light by the recombination of electrons and holes.  In the case of the OLED, when a voltage is applied across the device, electrons are injected at the cathode and provide electrons to the emissive layer(s).  The conductive layer provides electrons to the anode, leaving “holes” within the layer.  These holes migrate to the emissive layer where they recombine with the excess electrons.  As the electrons drop into the holes, they release energy in the form of light.  The color of the light emitted depends on the composition of the organic emissive layer.  Multiple layers (for example red, green and blue) can be combined in one device to produce any desired color including white.

Are OLEDs energy efficient?  OLEDs devices are extremely efficient with over 95% of the input energy converted to light.  Since the layers that make up the OLED are very thin, photons are not trapped within the active region, as can be the case with LED devices.

How expensive are OLED devices?  At present, OLED devices are very expensive.  Products on the market today are in the tens of dollars per lumen range versus $0.02/lumen for LEDs.  However, OLED manufacturers are making rapid progress in reducing the cost.  One potential manufacturing technique would allow sheets of OLED material to be printed in a continuous process, drastically reducing the cost.

How long do OLEDs last?  It depends on the color.  Presently, red and green materials have lifetimes that can exceed those of LED products.  Blue materials have relative short lifetimes of 5,000 – 10,000 hours, but are expected to improve within the next few years.