OLED: A Technology on the Cusp

By: Craig DiLouie

“Today, OLED is just a design topic,” said Karsten Diekmann, senior manager of marketing, product, and application engineering for OSRAM OLED (osram-oled.com). “Tomorrow, OLED is a valid alternative to everything.” In fact, a range of commercially available products are currently competing with LED and conventional lighting in various applications. The OLED source consists of a stack of organic (carbon-based) thin films layered between two electrodes and typically encased in plastic or glass. This results in a light source that is ultrathin—less than .08”—but can theoretically have a large area.

While the LED is a tiny and directional point source, OLED is a flat and diffuse area source. LED is well suited to providing focused light in a single direction while OLED is well suited to area ambient lighting. LED is very bright and, like conventional sources, requires external optics and shielding to direct the light and prevent direct glare. In contrast, OLED’s emission is very diffuse, with optics potentially built into the light source itself; as a result, the source can be viewed directly without glare.  

 Because the light source does not get hot during operation and doesn’t need heat sinking, it offers the potential to integrate with architectural surfaces and materials. The source’s characteristics allow it to be manufactured in custom shapes. It also has the potential to be manufactured as a flexible—and even transparent—material.

“As OLED advances in performance, continues to decline in cost, and takes shape in flexible forms, this technology will continue to advance lighting design and what it can do to enhance the spaces where people live, work, and play,” said Jeannine Fisher Wang, director of business development for Acuity Brands (acuitybrands.com).

Young even relative to LED (although emerging more rapidly), OLED has gained traction in the display and automotive markets. Several manufacturers have begun commercializing the technology for the architectural lighting market. Early applications are primarily demonstration, custom, and decorative projects, although some players are moving into general and niche applications such as task, sconce, pendant, display, signage, and wayfinding lighting and have products available today.

“In the past few years and even today, we see large custom installations,” explained Giana Phelan, director of business development for OLEDWorks (oledworks.com). “They create a ‘wow’ experience and are often animated with lightshows. More recently, we see OLED luminaires that target architectural and functional lighting applications while offering a very unique look.”

Wang noted that current OLEDs are typically sold to OEMs as panels that can be mounted individually or in assemblies with optics, drivers, and housing. OEMs than use the panels to develop OLED lighting solutions for use in traditional and innovative lighting applications.

The panel may be rigid or flexible. Panel shapes include rigid squares (2x2˝ up to 12x12˝), flexible squares (up to 12x12˝), rigid bars (1x4˝ up to 4x12˝), flexible bars (2x8˝), and rigid round (2˝ up to 4˝ diameter), with additional form factors emerging. While a luminance of 3,000 candelas per square meter is generally optimal for interior lighting, panels emitting up to 10,000 candelas per square meter are available for applications where the light source is not directly viewed (although higher brightness may entail a tradeoff in service life).

Several tones of white light can be specified, from a warm 3000K to a neutral 3500K to a cool 4000K, with some availability in 2700K and 5000K. Color rendering is good to excellent at 85 CRI to 90 CRI. Life has increased to 40,000 to 50,000 hours at L70.

“In the past five years, we made an average improvement of about 25% per year in efficacy and lifetime,” said Diekmann. “In five years, the gap to LED performance will be minimized, enabling the first penetration of functional lighting applications—not only design-driven applications.”

Wang added that the next five years will bring new drivers and control protocols, a shift to flexible substrates, improved color rendering (including an R9>50 for rendering of saturated reds), and improved service life up to 50,000 hours at L85. Manufacturers are also exploring how to incorporate OLED into walls, ceilings, and flooring and materials such as glass and furnishings.

While OLED solutions may include fewer components than LED and conventional lighting systems, cost remains a significant inhibitor to adoption of OLED because of manufacturing costs associated with the light source itself. Wang estimated OLED’s cost at $200 to $500/kilolumen at the panel level, but added that the cost of OLED lighting has come down 40% in the last year alone. In five years, she expects panel cost to fall tenfold.

“The biggest challenge for OLED is to become widely available at a significantly reduced cost,” she said. “While today it’s more affordable than many think, landslide cost reductions are certainly on the horizon as the technology transfers to production using flexible substrates.”

At present, OLED can be easily considered for projects designated as specialty areas. For certain types of luminaires, such as sconces, OLED lighting is already cost competitive with comparable LED solutions. OLED will become cost competitive with the more commodity-type lighting solutions such as linear pendants. The industry is making big investments toward achieving this goal and driving a timeline as short as three years from now.

“OLED adds a special flair to any project,” Wang added, “so electrical distributors should consider stocking some of the discrete-type OLED luminaires such as individual ceiling-mounted modules and wall sconces to offer their clients immediately available solutions that are truly unique.”

“OLED and LED are complementary SSL technologies; both are easily controlled, dimmed, and highly efficient. OLED’s naturally diffuse light quality, in a very thin package, is providing new inspiration for designers and luminaire manufacturers,” concluded Phelan.

*For more information go to www.tedmag.com

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