Considering the strong potential of the UVA LED business in UV curing, augmented by the growing market demand for UVC LEDs in air and water purification, Yole Développement of Lyon, France, forecasts a cumulated $250 million UV LED market in 2015. Because UVA LEDs are compact, cost-effective and environmentally friendly, they are expected to replace the traditional UV lamp business – a market estimated to be worth $500 million in 2008 – and to make way for new applications, particularly portable ones, according to the market analysis company’s UV LED Market Report – 2009.UVA LEDs to shine this year and nextFocused on UV LEDs based on GaN and AlN technologies, the report indicated that, in 2008, LEDs in the UVA/B spectrum (400 to 280 nm) held the largest share in sub-400-nm applications. It notes that more than 90 percent of the UV LED market was allocated to applications that required UVA/B sources, including UV curing, banknote counterfeit detection and medical instrumentation. The remaining 10 percent included a large segment of UVA-based LED sources (400 to 315 nm) for photocatalytic air purification. This air-cooled UV LED head is available with focusing lenses for spot cure of adhesives or inks. Photo courtesy of Clearstone Technologies Inc.UV LED light sources definitely can compete with traditional mercury lamps in the UV curing business, according to Yole Développement. Compared with mercury lamps, UV LEDs are smaller, nontoxic, more resistant to breakage, have longer lifetime expectations and shorter warm-up times, and easily can be adjusted for system integration. In the area of heat management, back-sided heat extraction is needed with UV LED devices, while traditional UV lamps have homogeneous heat distribution. UVA LEDs’ long lifetimes, lower maintenance costs and power supply cost reductions have contributed to overall lower costs that are competitive with the traditional UV lamp sources. The power output of LEDs has greatly increased, and several watts per square centimeter are expected to be available this year and in 2010. According to the report, many new companies have emerged at the system and LED packaging level.Today’s UV LED market is oriented mostly toward UVA-emitting diodes because of their similarity to blue GaN diodes, according to Dr. Philippe Roussel, project manager of compound semiconductors and advanced materials at Yole Développement. The major difference in the UVA emitting diodes is a higher aluminum content in the AlGaN compound active layer and specific packaging that is resistant to UV light – enabling applications in UV curing, banknote detectors and photocatalytic air purification, he said. The improvement of UVA LEDs’ performance (lumens per watt and output power) will enable them to gradually assume market share over the traditional UVA light sources, he added. UVC LEDs to bloom laterThe next booming market is expected to be related to the use of LEDs in the UVC short-wave, or germicidal, range (280 to 100 nm), which will open the door to water- and air-purification applications, according to Roussel. He added that we can expect to see the introduction of commercial air and water disinfectant products by 2010 and 2011 and to see UVC LED applications covering more than 50 percent of the UV LED market by 2013 and 2014. The growth of the UVC LED market is connected strongly to the availability of AlN bulk substrates that theoretically could multiply by 100 the LED chip optical power output, according to Yole Développement. It expects that several companies will provide AlN wafers in volume at the end of 2009. Roussel said that AlN bulk substrates probably are key to achieving highly efficient UVC LEDs. The substrates will improve their emission power greatly, he added.Portable water purificationMiles Maiden, founder, CEO and chief technology officer of Hydro-Photon Inc. in Blue Hill, Maine, said that his company demonstrated the use of UV LEDs in water purification in 2004 with funding provided by the US Office of Naval Research and with support by DARPA’s Semiconductor Ultraviolet Optical Sources program. Maiden invented the SteriPen, a portable water purifier that uses UV light to destroy waterborne microbes. The company does not have a model that uses UV LED technology, but one is in development. Maiden said that deep-UV LEDs hold promise for even smaller, lighter and faster SteriPen water purifiers, eventually at significantly lower prices. The inherent advantages of UV LEDs could make them particularly suitable for water purification within a humanitarian context, he added.