Europe is alight with LED developments these days. In every corner of the continent, researchers and companies are pushing the technology toward dazzling new applications and capabilities.
The high-brightness LED market is expected to reach $16.2 billion in 2014 with increased use in TV backlighting and mobile devices as well as lighting, according to LED market research firm Strategies Unlimited of Mountain View, Calif.
As demand rises, LED manufacturers must seek out new technologies and methods that bump up lighting efficiency but keep manufacturing costs down. And several European projects are rising to the challenge.
Part of the reason for the LED push is the European Union’s ban on conventional lightbulbs, said Dr. Thomas Glinsner, head of product management at EV Group (EVG) in St. Florian, Austria. After 2009, bulbs that used 80 W or higher power were removed from the market; the EU’s road map calls for this to continue with lower-power lamps as well. So LEDs for lighting are set to take off in a big way, especially in Europe.
“LEDs will be the light technology of choice in the future, not only in Europe, but also globally,” Glinsner said. “We can also say that European governments have been supporting R&D activities in this direction, which is leading to development of new technologies.”
EVG recently teamed up with lithography pioneer Eulitha AG of Villigen, Switzerland, to establish a new low-cost nanopatterning solution for manufacturing high-brightness LEDs. EVG makes wafer-processing products for semiconductor, microelectro-mechanical systems and nanotechnology; Eulitha is a spin-off company of the Paul Scherrer Institute and specializes in lithographic technologies for applications in optoelectronics, photonics, biotechnology and data storage.
Eulitha and EV Group are working to combine their technologies to improve production of high-brightness LEDs. Here, the Phable platform has generated a hexagonal pattern with a 300-nm hole diameter. Courtesy of EV Group/PR Newswire.
The two companies signed a joint development and licensing agreement to integrate Eulitha’s Phable mask-based ultraviolet photolithography technology with EVG’s automated mask-aligner product platform.
Phable – short for “photonic enabler” – was designed for low-cost production of periodic nanostructures. “It enables production of periodic nanostructures that are five to 10 times smaller than what can be obtained with the conventional mask aligner technology,” said Harun Solak, CEO of Eulitha.
In the new Phable concept, Solak added, special manipulation of the mask-wafer gap during exposure eliminates the diffraction limit. “This means that the resolution limit in a Phable tool is only determined by the wavelength, rather than the mask-wafer gap. If we compare this new technology with projection lithography (i.e., steppers), a Phable tool has resolution equivalent to a projection tool with imaging optics having a numerical aperture of 1.”
A scanning electron microscope image of a hexagonal pattern with a 300-nm hole diameter and 600-nm pitch generated by Eulitha’s Phable UV photolithography technology. Courtesy of Eulitha AG.
The mask aligner technology’s low cost of ownership, plus its ability to resolve periodic submicrometer patterns, will be useful for LED manufacturers, the companies said, especially for patterning of sapphire substrates.
The combined technologies will offer low-cost, automated fabrication of photonic nanostructures over large areas, supporting production of energy-efficient LEDs, solar cells and liquid crystal displays.
The cost of ownership will be lower than with other techniques, the companies said. Proximity lithography’s noncontact capabilities, when used at submicron resolution, enable easier patterning of sapphire substrates to enhance light extraction – and, thus, the efficiency – of LED devices.
“Improving the efficiency and reducing manufacturing cost are the two main knobs permitting LEDs for general lighting,” Glinsner said. “So, in the end, it is all about cost-per-lumen and cost-per-wafer.”
“The synergies of our respective technologies have great potential to provide the resolution and volume production capabilities of lithography steppers at a fraction of the cost – enabling LED, optics and photonics manufacturers with extremely tight cost constraints the opportunity to extend their technology road maps to higher levels of performance,” said Eulitha’s Solak.
Demo capabilities are already in place, the companies report, and the first products are expected to ship this year.
“The integration of Phable into mask aligners enables significant resolution enhancements down to 200 nm,” Glinsner said. “Targeting a high-throughput system enabling high resolution will help customers to run processes at low cost of ownership.”
In Cork, Ireland, Epi-Light Ltd. has come up with Exci-Light, a new high-brightness LED with a narrow spectral output and a uniform beam for biofluorescence illumination. The company focuses primarily on high-brightness-LED-based optical products for specific applications in the life sciences and industrial markets.
The Exci-Light is a high-brightness LED with a narrow spectral output and a uniform beam for biofluorescence illumination. Courtesy of Epi-Light Ltd.
The Exci-Light, a member of the epiEXCI family of products, was released just in time for January’s SPIE Photonics West 2012 trade show in San Francisco; it is an extremely compact and sensitive illuminator for biofluorescence applications.
The combination of high brightness, narrow spectral output and a large, uniform beam was designed for high-speed, high-sensitivity fluorescence imaging applications. The instrument also is modular, so it can be used for gel documentation, microtiter plate analysis, microarray analysis and in vivo diagnostics, among other applications. Fluorescent probes compatible with the Exci-Light include SYBR Green, SYBR Gold, SYBR Safe, Alexa Fluor 488, Cy2, green fluorescent protein, SYPRO Ruby and SYPRO Orange. Other emission wavelengths are available as well.
“The Exci-Light was first developed in 2007 as an extension of the Projector-Light product. Continuous refinement during development projects, together with leading customers in the field of fluorescence imaging, has led to today’s design,” said Niall Bolster, sales director at Epi-Light.
The high-brightness LEDs can be used for a wide range of applications. “We are seeing a substantial amount of interest in UV applications for life sciences as well as curing applications in the printing industry,” Bolster said. “In the areas of IR, we are currently working on projects for the [information technology] and biometrics markets.” The company now offers single- and multichip arrays for fluorescence applications, including DNA testing, and gene, protein and cell analysis.
“Europe is now becoming more competitive than ever both in terms of industry and of research/education,” Bolster said. “In my opinion, European countries have always focused strongly on R&D, innovation and education, and this is benefiting companies in industry today.”
Epi-Light collaborates with local research institutes as well, including Tyndall National Institute at University College Cork and the Centre for Advanced Photonics & Process Analysis at Cork Institute of Technology, Bolster added. “The existence of a cluster of LED-technology-based companies and research institutes helps to strengthen the group’s knowledge and understanding, which in turn gives a distinct edge in today’s marketplace.”
One new LED product emits a continuous spectrum from 400 to 750 nm. Called the Wispec-LED, it is made by IMM Photonics GmbH of Unterschleissheim, Germany, which supplies laser technology, optoelectronics and fiber optics for a range of applications, including manufacturing and spectroscopy.
The Wispec-LED was developed specifically as a replacement for halogen lamps; other applications include color measurement and microscope illumination. Courtesy of IMM Photonics GmbH.
Standard white LEDs have a gap in the spectrum between 400 and 450 nm as well as at around 500 nm, according to the company, which developed the Wispec-LED to close that gap. Four chips team up in the new LED to deliver homogeneous white light. Each chip can be controlled independently of the others, so the light can be individually adjusted for different applications. Pulse width modulation allows the LED to be dimmed by a ratio of 1:400 without changing its color temperature.
The new LED was developed specifically as a replacement for halogen lamps; other applications include color measurement and microscope illumination. The company already has seen “huge interest” in the technology, according to Ulrike Hütter, a sales assistant.
Hiding bright spots
Nanocomp Oy Ltd. in Lehmo, Finland, also had new LED-related products on display at Photonics West – specifically, the company was showcasing its NAFfuser, a solid-state lighting foil designed to hide bright spots in LEDs. The company enables design, tooling and mass production of thin-foil optics with products for handheld devices, solid-state lighting and diffractive pattern generators.
Light control traditionally has required injection-molded lenses that are too thick for LED arrays and that demand precise assembly, but the NAFfuser has no such requirements. The lens foil simultaneously hides bright spots caused by LEDs and collimates light, without the need for hyperaccurate assembly, and functionality is not affected by the LED’s position relative to the foil’s lengthwise position. NAFfuser also hides LED spots when not illuminated. The generic lens foil solution is thin, flexible and easily integrated with LED systems. It also can be laminated on any surface, including glass.
Frankfurt Laser Co. of Friedrichsdorf, Germany, distributes mid-IR LEDs and photodiodes from LED Microsensor NT of St. Petersburg, Russia, that operate in the range between 1.58 and 4.45 µm. The intended application is gas measurement – either determining gas concentration or detecting a specific type of gas in the air. They can be pulsed-mode or quasi-continuous-wave to achieve either high-peak-power output or high-average-power output.
The LEDs were developed at Ioffe Physical Technical Institute in St. Petersburg, according to Dr. Vsevolod Mazo, sales director at Frankfurt Laser Co.
“Absorption bands of practically all important chemical substances lie in the middle-infrared spectral range,” Mazo said. “[These] new mid-IR LEDs open exciting possibilities for development of new-generation miniature optical sensors for analyzing of gas, liquid and solid environments.”
Additional applications for the mid-IR LEDs include medical diagnostics, environmental monitoring, and CO2 methane and water vapor sensing.
Because the LEDs are so new, companies have requested samples to evaluate sensor system designs using them. It will take time for customers to take advantage of all the benefits of LEDs for chemical sensors, Mazo noted. “We expect a strong increase in volume of mid-IR LEDs within the next two to three years.”
Several large orders have already been placed, most coming from the US and Japan, he added. “We hope that European companies that produce chemical sensors and sensor systems will pay more attention to the new possibilities that mid-IR LEDs open in this field.”