OLED lighting was envisaged as having many dramatic advantages. It is a long time since it was thought that it could match the lifetime of LED lighting anytime soon but better colors, dimmability, lower cost, wide areas, flexible film forms and other benefits are still promised. However, LEDs have taken three percent of the global lighting market while we have been waiting for OLEDs to appear in anything more than very specialist applications. Meanwhile, the technology of LEDs progresses in leaps and bounds, though they remain thin film, point sources of light, not printed. For example, they are now dimmable, even longer lived and potentially even lower in cost - dramatically so.
The latest news comes from scientists at Cambridge University in the UK who claim they can produce LEDs for a tenth of current prices. They say this could see household lighting bills reduced by up to 75% in five years time.
Since the 1990s gallium nitride (GaN), which is used to make LEDs, has been grown in labs on expensive sapphire wafers making production costs for GaN lighting too expensive for widespread use in homes and offices. Now the Cambridge team have discovered a new technique that grows GaN on silicon wafers which can achieve a 50% improvement in cost and efficiency.
A GaN LED can burn for 100,000 hours which means that, on average, it only needs replacing after more than 11 years. These types have the advantage of turning on instantly and being dimmable. Disposal is simple as, unlike currently available energy-saving bulbs, GaN LEDs do not contain mercury eliminating any environmental problems.
Professor Colin Humphreys, lead scientist on the project said: "This could well be the holy grail in terms of providing our lighting needs for the future. We are very close to achieving highly efficient, low cost white LEDs that can take the place of both traditional and currently available low-energy light bulbs."
Clearly both LEDs and OLEDs will be far better than the current saviour of the world, the compact fluorescent bulb with its glass to cut you, mercury to poison you, rare terbium and awkward shape. However, OLED lights may be narrowed down to having the uniques of being wide area, tightly rollable, needing no fitment and being transparent until needed. Will they tolerate the temperature range of alternatives and will they have a life of more than a few years? That remains to be seen.
IDTechEx sees OLED lighting taking a percentage of the lighting market alongside LEDs, rather than in their place, and OLEDs will create many new lighting markets, including as origami artwork and lighting on apparel and as indicators on e-packaging and medical disposables. But the options are narrowing and costs remain a challenge.
For more attend Printed Electronics Europe 2009 and read Inorganic and Composite Printed Electronics 2008-2018.
