cintelliq - lighting



home \|	newsletter \|	reports \|	consultancy \|	conferences \|	about us \|	resources

lighting: an opportunity?

A study conducted by R Haitz and Fred Kish et al, published in 1999, presented the case for a national research program on solid-state lighting (SSL). The study highlighted that 20% of all electricity consumed in the United States is for lighting. The study concluded that if new sources of light, in this particular case those based on semiconducting materials, were given additional financial resources to accelerate their technological developments then performance would improve so significantly that they could potentially reduce overall global electricity consumption by 13% and reduce carbon emissions by 2.3%.

The technology available for SSL can be either inorganic light emitting diodes (LED) or organic light emitting diodes (OLED). Both rely on materials that exhibit semiconducting properties. Until fairly recently the use of LEDs in lighting applications were ruled out on two accounts: limited technical performance and high cost when compared to incumbent lighting technologies — fluorescent and incandescent lamps. However, rapid advancements in LED technology has led to improvements that has enabled a new generation of LEDs that offer high brightness, improved efficiencies and lower costs.

LEDs are more suited as a replacement for point sources of light — incandescent lamps. OLED technology, while closely associated with displays, is equally suited as a replacement for diffused lighting sources — fluorescent tubes. SSL is now seen as a very viable lighting technology. Not only will SSL save energy it will offer a broader range of options for developing novel lighting systems.

To be successful, especially in the longer term, SSL has to offer efficiencies and lifetimes beyond those already attained with conventional lighting technologies.

Efficiencies and lifetimes of solid-state lighting are now approaching that of conventional lighting
Lighting technology	Efficiency (lm/W)	Lifetime (hours)
Fluorescent	80	10,000-20,000
Halogen	20	3,000
Incandescent	15	800-3,500
Inorganic	50	50,000 +
Organic	10-40	3,000-20,000

Using historic and projected data R. Haitz and colleagues plotted performance and cost changes over time. Their analysis lead to the observation that, for red LEDs, lumens per package increased at a rate of x30 per decade and cost per lumen reduced by x10 per decade.

It is expected that efficiencies of LEDs should easily achieve 200 lm/W. An upper limit of 683 lm/W has been suggested but has not yet been confirmed in practice.

The 13% energy savings mentioned above where based on achieving, on average, 150 lm/W efficiencies for SSL. OLED technologies have some way to go, but the technology is expected to achieve the necessary efficiencies required. OLED technology holds the promise of being manufactured on flexible substrates via the use of a roll-to-roll production process. This is expected to enable OLED to achieve a superior cost advantage over LED for large area diffused lighting applications.

According to an article in Physics Today red LEDs cost $0.06 per lumen in 2000, still more expensive than incandescent lamps. In 2002 white LEDs are expected to cost around $0.20 per lumen. If costs can be continuously reduced at a rate of x10 per decade then by 2005 white LEDs will cost $0.05 per lumen, and by 2012 will have reached $0.01 per lumen (a target cost that is often quoted as being the point when SSL becomes economically viable as a source for general illumination).

If SSL has the potential to become economically attractive, how large is the market opportunity? A recent report by Strategies Unlimited highlights the market opportunities for high brightness LEDs (HB-LEDs) as the main contender to replace incandescent and fluorescent lamp technologies. According to the report the market for HB-LEDs used in lighting applications is projected to grow from $85 million in 2002 to over $500 million in 2007.

The overall market for HB-LEDs is larger. It has grown nearly 50% per year since 1995, reaching $1.2 billion in 2001, and is seen as a major catalyst for revitalizing the 30-year-old LED business. Typical applications have included traffic signals, large outdoor single-colour and full-colour signs, automotive exterior and interior lighting, and LCD display backlighting. LEDs have also begun to address a number of lighting applications such as architectural lighting; machine vision; illumination for signage; decorative, accent and marker lights; and flashlights.

The majority of solid-state lighting applications to date have involved coloured light. However, white light illumination is seen as the ultimate goal of the LED industry. White LEDs, introduced in the late 1990s, have made tremendous progress in efficiency and lumen output, with efficiencies now exceeding those of incandescent lamps. As a result, white LEDs are now poised to enter the $12 billion market for general illumination.

What will be the market opportunity for OLED based solid-state lighting?
Who is leading the technological development in this industry?
How much resource is being invested to push the technology forward?
What patents have been filed and published?
Are polymer based materials more relevant than small molecule materials?
When will roll-to-roll process technology be available for lighting?
What are the key technological challenges facing the development of solid-state lighting based on OLED technologies?