Below is a reprint of an article about OLED lighting I contributed to the June issue of TED Magazine:
Organic light-emitting diode (OLED) is an exciting novel lighting technology. Popular for small-screen display applications such as cell phones, it’s now rapidly developing as a commercial light source.
The OLED source consists of organic (carbon-based) thin films stacked between two electrodes and typically enclosed in plastic or glass. Light is emitted across a material that has a very small thickness but a very large area. This results in a number of benefits.
“OLED is intrinsically a diffused, large area light source, which lends itself to providing soft, glare-free illumination without the need for louvers, reflectors, lenses and other methods of optical control,” says Jeannine Fisher Wang, director, business development and marketing, OLED Business Group, Acuity Brands. “Therefore, OLED is inherently an approachable light source, which also makes it possible to place the light source closer to the user, enabling designs based on the concept of application efficiency.”
Image courtesy of Acuity Brands.
Unlike LED, OLED sources do not get hot during operation, which means they do not require heat sinking. “This allows them to be used in contact with many materials not usually associated with lighting fixtures, such as fabric, wood, plastics and even paper,” says Stephen Blackman, chief design officer for BlackJack Lighting.
The light emission characteristics of OLED make it a complementary technology to LED. The LED is a point source well suited to directional applications such as downlights and accent lighting, while OLED is well suited to area lighting applications such as general ambient office and classroom lighting.
Blackman sees a particularly strong application in “back against the wall” applications such as wall sconces and luminaires that are mounted flush to the ceiling. This is because the OLED material emits light in a single direction as opposed to incandescent and compact fluorescent lamps typically installed in these luminaires.
“With these light sources, we lose up to half of the light that is being sent into the back plate of these fixtures,” he says. “This is not so when using directional OLED panels in these types of luminaires.” The result is higher efficiency and smaller, lighter hardware.
A final benefit is the potential for flexibility and unique form factors, with the ability to be field-cut or bent into custom shapes and configurations. There is also potential for OLED to be manufactured as transparent and mirror surfaces, enabling windows and mirrors that become light sources when energized. “OLED lighting offers the intriguing possibility of new and even futuristic form factors, because OLEDs can be made to be thin, lightweight, flexible, transparent and in almost any shape imaginable,” says Jim Brodrick, SSL Program Manager for the U.S. Department of Energy.
OLED is a young technology that Blackman says is seven years behind LED. As a result, current application is limited to decorative, high-end and feature-space applications. Suitable applications include high-end residential, restaurants, hospitality, feature lobbies, reception areas and large-scale public spaces. Many installations are one-off demonstration projects, though some standard decorative chandelier, sconce, task and emergency/exit products are available. A number of companies such as as Acuity Brands, Blackbody, BlackJack, Novaled, OSRAM, Philips, WAC and Zumtobel have demonstrated OLED luminaire concepts, some of which have been offered for commercial sale.
“The types of luminaires we see encompass a broad range of products to support corporate, hospitality and residential interiors and statement spaces,” says Pete Shannin, vice president and general manager, OLED Business Group, Acuity Brands. “We fully expect OLED luminaires to become more available in broader architectural lighting segments as OLED performance and price features improve.”
Image courtesy of OSRAM SYLVANIA.
“OLED technology is a work in progress,” Blackman adds. “The technology is changing very quickly right now. It would be difficult to stock any of the OLED panels right now since the technology will obsolete these light sources within the year. There are, however, some very good OLED suppliers out there that are more than happy to educate electrical distributors about their OLED panels for special order for many custom applications right now. There are many complete systems of OLED panels with matching drivers that make it easy for their specifier customers to easily use them in many architectural installations both for purely artful installations but also in functional custom furniture, task areas and accent lighting.”
As Blackman suggests, OLED lighting consists of OLED panels mounted individually or in assemblies with housing and compatible drivers (which supply low-voltage power and control). The panel may be square, rectangular (“bar”) or round, with square and rectangular being most common. A typical panel is 4 in. x 4 in., about 1/16-inch thick, and emits up to 200 lumens at an efficacy of 40-60 lumens/W. The light may be a single-color or tunable, including white, using a red/blue/green mix. White light color temperatures range from 2700K (warm) to 5000K (cool), with good color rendering (80-90 CRI). Rated life is 10,000-15,000 hours depending how much light output is desired.
Wang says research and development is moving fast and will result in OLED panels achieving higher brightness, CRI up to 95+ and efficacy as high as 120+ lumens/W within five years. “We also expect an evolution of available form factors, adding more variety in shape and size, as well as other characteristics such as flexibility, transparency, RGB and tunable white,” she says.
OLED must cross some significant hurdles, however, before becoming competitive for the general lighting market, requiring significant performance and manufacturing improvements. The biggest issue is cost.
“The main barriers facing OLED lighting technology today are that it’s way too expensive, hasn’t yet been tested in the field, and will have to compete with an ever-growing and rapidly improving range of LED lighting products,” says Brodrick. “The cost question alone is a formidable one. OLEDs intended for general lighting require a large amount of expensive materials as well as the ability to minutely control the deposition of nanometers-thick layers of material across substrates that could be several meters wide. The bottom line is that creative approaches are necessary to bring OLED lighting to commercial realization.”
Image courtesy of Acuity Brands.
“OLED technology needs to address the obvious problems—high cost, low efficiency and only moderate operational life,” says Blackman. “These challenges are being addressed and are following a path similar to LED development. These hurdles can and will be overcome.”
He adds that the “killer apps” for OLED are not fully in focus yet. “As the technology develops, new features and benefits will emerge that will make it obvious where this technology is best suited to the industry,” Blackman says. “It is not a matter of if but when it will happen.”
For now, Shannin encourages electrical distributors to get to know the technology and where it might fit in their projects. “OLED luminaires will be the lighting of choice for clients looking for innovative and inspiring solutions,” he says. “You will leave your signature on any project where you use OLED luminaires.”
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