The LED Revolution
LED technology drives innovations in general lighting and the life sciences.
Mention light emitting diodes (LEDs) to most people today and they probably think first of lighting. General awareness of LED-based lighting has been boosted of late by increasingly widespread adoption of LEDs in a range of common lighting applications from supermarket refrigerators to street and automobile lighting and the presence of LED-based alternative-lighting products at hardware stores.
Media coverage of LED-based lighting, driven by high-profile product announcements and the emergence of novel lighting applications for consumers and in the life sciences has also helped raise public consciousness of LEDs and their applications.
Now a little over 50 years old, LED technology is driving a revolution in general lighting that spans the globe. The unique combination of LED size and efficiency has enabled artificial lighting to reach parts of the world that have never before been able to enjoy its benefits.
Of course there are other significant markets for high-brightness LEDs, though many are starting to show signs of maturity. According to Ella Shum, conference chair at Strategies in Light in February, the use of LEDs for general lighting represented only 23% of the 2012 LED market, estimated at $14 billion.
Other segments include backlighting of TVs and monitors (22%), mobile (19%), signage (13%), automotive (10%), and the inevitable “other” category (13%), which includes many niche applications that are emerging as some of the benefits of LED technology are more fully developed.
It is lighting, however, that is getting everyone excited, says industry analyst Bob Steele, who has been tracking the emergence of LED technology and markets for almost 20 years. “It is a market in its early stages,” he says, and because LED penetration of the general lighting market is low, “there’s plenty of room for growth.”
Furthermore, Steele notes, LEDs are truly transforming the entire general lighting business.
The inexorable progress of solid-state lighting technology is fueled by a unique combination of engineering advances, falling prices, and lighting-policy support from many of the world’s governments as they seek light sources that are more energy-efficient than the traditional incandescent light bulb. And while market analysts all agree on the fact that LED market penetration of general lighting markets is accelerating — some say skyrocketing — their actual market estimates vary wildly.
Definitional differences combine with varying estimates of future price erosion and difficulty reconciling demand and supply side forecasts to produce a confusing array of numbers.
At Strategies in Light, analyst Vrinda Bhandarkar pegged the 2013 LED lighting market at $17 billion with a compound annual growth rate of 12% projected from 2011 to 2017. A recent report from Digitimes Research (Taipei), however, projects the market will grow 54% from 2012 and reach $25.4 billion in 2013.
These forecasters are also challenged by the fast-moving technology advances — and apparently, so is the U.S. Department of Energy. In April 2012, the DOE projected that the industry would not achieve efficiencies of 160 lumens per watt for LED lamps until 2015. In fact the DOE’s own web-based product-search tool currently doesn’t even offer the option of searching above 200 lumens/watts.
However, startup Green Ray in the United States announced in April an LED-based fluorescent tube replacement operating at 173 lm/W, and Philips announced a similar product prototype at 200 lm/W.
Both these devices are likely to further accelerate adoption of LED lighting. Current fluorescent-tube lamps top out at around 100 lm/W, so the prospects for an LED-based tube replacement with double the light output are … bright!
Unlike many technology developments that are essentially incremental advances, the advent of LED-based lighting is truly transformative—the point made by Steele. It is fundamentally changing the lighting industry, from product concept and specification all the way through manufacturing and supply chains. Even the end market itself is being changed by novel lighting products that have never previously existed.
Some can be extremely compact, for instance, or can change color or brightness at the touch of a button. In some cases, LED bulbs can be controlled remotely by a smartphone app.
At the product-concept stage, the ability to control the brightness and color as well as modulate LEDs is spawning an entirely new design process, including new design software for predicting the distribution and intensity of the light — not just of the devices themselves but also at the end-use level in room and building design, for example.
At the fabrication stage, materials systems are also part of the competitive mix, with some LEDs made on silicon carbide (Cree) and others on gallium nitride (Soraa) or sapphire substrates. (See "GaN LEDs could cut costs, improve efficiency" below.)
Hence the traditional industry leaders like Philips and Osram Sylvania, even as they develop new lighting products, are busy reinventing their business models as well. The longevity and efficiency of solid-state lighting as compared to traditional incandescent and fluorescent bulbs means these companies are gradually losing a profitable line of consumables even as they enter a series of newly forming markets.
At the same time, new entrants like Cree and Soraa in the United States and a multitude of companies in Japan and Asia are introducing competitive lighting products. Some, such as Soraa with its novel dimmable halogen bulb replacement (launched early in 2012) are staking out specific positions in the marketplace. Others are simply going after the LED-based replacement business for 40-, 60-, and 100-W incandescent bulbs.
Philips projects that by 2015, LEDs will have penetrated about 45% of the global lighting market. Digitimes Research says 39%. Such penetration rates are aided by the fact that many countries have now banned the manufacture of new incandescent bulbs at typical outputs.
These market estimates are further confused by an ongoing redefinition of markets and applications, some of which will likely add to the total available markets for LED lighting. In one example, rolls of sticky-backed tape are now available with embedded LEDs. The LEDs can change color and the tape can be cut to length and affixed pretty much anywhere to provide a strip of colored accent lighting.
Looking further down the road, LEDs have spawned many development efforts aimed at understanding the potential of LED-based lighting and taking it into new areas such as medical research and horticulture.
In India, Wipro GE, a joint venture between General Electric Co. and India’s Wipro Ltd., is fielding an LED-based phototherapy system for treating jaundiced newborns. The system uses much less power and works faster than conventional systems.
And researchers at Washington University School of Medicine in St. Louis and University of Illinois at Urbana-Champaign (USA), have developed implantable light-emitting diodes to study brain cells, behavior, and disease.
The LEDs are thousands of times smaller than those currently available commercially and have been implanted into mice brains to activate special networks of light-sensitive neurons.
“This strategy should allow us to identify and map brain circuits involved in complex behaviors related to sleep, depression, addiction, and anxiety,” says Michael R. Bruchas of Washington University. “Understanding which populations of neurons are involved in these complex behaviors may allow us to target specific brain cells that malfunction in depression, pain, addiction, and other disorders.”
This use of LEDs in optogenetics, adds Illinois materials scientist and SPIE member John Rogers, “provides a recipe for delivering all sorts of advanced technologies, such as full integrated circuits down in the brain.”
Photos courtesy John A. Rogers.
Meanwhile, a five-year, $4 million partnership between the Dutch government’s Technology Foundation STW and Philips recently launched eight new LED-related research projects, including an attempt to understand why LED light on growing tomato fruits doubles their vitamin C content.
Another project is aimed at developing more efficient green emitters by incorporating aluminum gallium phosphide (AlGaP) nanowires into the semiconductor layer structure.
Such research is likely to further boost the market for LEDs, be it for lighting or other yet-to-be-invented applications, and make them all the more commonplace in the future.
–Stephen G. Anderson is industry and market strategist for SPIE.
A new facility for growing gallium nitride – the key material needed to make energy-saving LEDs – has opened at University of Cambridge (UK), enabling improvements to cut the cost of LED lighting by 50% while improving efficiency.
GaN LEDs are already used in traffic lights, bicycle lights, TVs, computer screens, auto headlamps, and other devices, but they are too expensive for more general use in homes and offices.
The new GaN growth reactor, funded by the Engineering and Physical Sciences Research Council, will allow further improvement of a method to grow low-cost LEDs on silicon substrates instead of costly sapphire and silicon carbide.
Sir Colin Humphreys, a professor of materials science and metallurgy, says making GaN LEDs more cost-effective could unlock benefits far beyond energy saving alone. Beams from LEDs could transmit information from traffic lights to cars, for example, and ultraviolet LEDS could purify water supplies by killing off bacteria and viruses.
Humphreys was a co-author of a paper presented in the GaN Materials and Devices conference at SPIE Photonics West in February 2013 titled, “Changes in the Mg profile and in dislocations induced by high temperature annealing of blue LEDs.”
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