It’s always the way with technology: you’re only just starting to get your head around the newest piece of kit on the market when something comes along and renders everything you’ve just learnt obsolete.

Light-emitting diodes (LEDs) have long been hailed as the future of architectural lighting, their versatility, ease of control, durability and environmental credentials enthusing the architectural community for some time prior to their large-scale use becoming financially viable.

Artificial light as architectural material

As the price point has dropped steadily, however, architects have found themselves a new toy with which to experiment, enabling interplay between structural form and lighting that had been previously impossible. Single-pixel LED integration allows for the creation of matrixes and patterns in a variety of shapes, sizes and forms. In recent years, we’ve seen ever-larger and more ambitious media walls and illuminated building envelopes, and have arrived at a point where artificial light is now discussed as an architectural material in and of itself.

"OLEDs transport electricity through incredibly thin, organic, semi-conductive layers."

But, as architectural LED use has become more common, many manufacturers, developers and architects have decided to look beyond the mainstream, setting their sights on ‘the next big thing’. This would appear to come in the form of organic light-emitting diodes (OLEDs), which – unlike incandescent bulbs that pass electricity through wire, or fluorescent lamps that pass current through gas – transport electricity through incredibly thin, organic, semi-conductive layers. While an LED emits light from a single point bulb, an OLED is a flat light source, meaning it produces homogenous output and incredibly low heat emissions across an extremely light, thin and potentially large surface area without the need for any backlight. The panels themselves can be bent, rolled and manipulated.

In truth, the general consensus is that an OLED is more likely to work in tandem with an LED than replace it entirely, but, being novel, manipulable and ecologically sound, it is unsurprisingly generating a growing buzz across design blogs and at international trade shows. Discussion of its use within the built environment, however, may remain at the theoretical phase for some time to come. For starters, due to its low thermal conductivity, an OLED currently emits far less light per the equivalent area of an inorganic LED.

Luminous efficacy

Luminous efficacy is a measure of how well a light source produces visible light: the ratio of luminous flux to power. The best large-area OLED panel currently has an efficacy of 50Lm/W, some way short of LED standards. A technology road map published by the US Department of Energy has projected an increase to 105Lm/W by 2015 and 157Lm/W by 2020, although manufacturers have characterised such estimates as conservative in the extreme. There is some debate over how much progress will be made and how quickly, but the overriding mood within the fields of design and architecture appears to be one of cautious optimism.

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By GlobalData
"At present, OLED use is far more ambient than functional, but that will change."

"We’ve seen a lot of progress in the last few years alone," believes Simone Collon, Europe lighting leader at Arup. "The individual plates are still relatively small, but they’re getting bigger and we’re seeing them being assembled into chandeliers, wall displays, light installations and the like. The next stage of this process will be putting all these OLED plates together and creating entire surfaces.

"Development is so fast that we’re only looking at a time frame of five years or so before building façades and huge interior spaces might be a possibility."

Functional vs decorative light

While efficacy remains an issue, OLEDs’ use as a design tool remains purely decorative. But panel sizes are growing quickly: current prototypes range from 5×5cm to around 15×15cm, but panels of more than 60×60cm are already under discussion. The slenderness of such panels over a much larger scale is particularly exciting for those exploring its uses for interior, and eventually exterior, architecture.

"What makes it so intriguing is that we are talking about such a thin layer – it can be integrated into almost any surface you want," says Collon. "The light no longer has a thickness and the requirement for having an actual shape disappears – in fact, shape itself doesn’t matter. With the ability to weave OLEDs into materials and organic shapes, light becomes the actual surface. The LED is still a point source, but with OLEDs we are talking about surface light. It promises a real return to minimalism."

"The requirement for having an actual shape disappears – in fact, shape itself doesn’t matter. Light becomes the actual surface."

Alongside luminous efficacy, the other big stumbling block regarding widespread use remains affordability. It is, therefore, unsurprising that a large number of projects currently highlighting the potential of OLEDs within the built environment are being commissioned and funded by the manufacturers themselves.

A prime example of what is currently possible is Torafu Architects’ installation for chemical manufacturer Kaneka Corporation at Milan’s Salone del Mobile. Inspired by yozakura, the traditional Japanese custom of viewing cherry blossom by night, 2,500 OLED panels, decorated with paper petals, were suspended within an extensive dark space, creating a chain of light floating at various levels over more than two storeys.

Soft illumination

Light within the room moved sporadically from complete darkness to soft illumination, with mirrored walls further heightening the effect of depth and scale. Kaneka’s own dimmable panels were used and, at $24,000/m², Torafu will have been glad not to be picking up the tab, but the manufacturer has already gone on record claiming the cost could come down to a tenth of that amount. What an installation such as this really helps to emphasise is the calm, noble quality of OLED illumination, requiring none of the taming of traditional light sources and without the single point of an LED.

"The glow is very gentle," Collon agrees. "That softness of illumination creates a magical effect and opens up a number of interior and exterior opportunities, including glowing wallpaper and false internal windows. At present, it is far more ambient than functional, but that will change."

Flexible applications

One company interested in exploring what that change might look like is Konica Minolta. The Japanese technology giant challenged a range of architects and designers to forget about price or present capabilities, and instead envisage uses for OLEDs under the working title ‘Lighting the Earth for the next generation’.

Proposals included ‘curvilinear light vessels’ – flexible, scaleable OLED sculptures ranging from reading lamps to outdoor illumination – from German architects Fomalhaut. But a lot of the attention focused around the work of Mexico City-based design firm AGENT.

The studio, founded in 2009 by architect Michel Rojkind and industrial designer Alberto Villarreal, presented a twofold response. The first proposal, highlighting the flexible nature of OLED technology, focused on the development of ‘functional jewellery’: lightweight and bendable wrap-on accessories with the thinness of cloth that could be both decorative and worn as safety apparel when travelling at night.

Illuminated bus stops?

Garnering more attention among non-cycling architects, however, was Strip Light, a programme that started out as an effort to fuse communal areas with street lighting. Flexible OLED panels are bent at various levels to form benches of light, serving as both public seating and display surfaces. Illuminated bus stops, for example, would include interactive neighbourhood maps, into which one taps a destination and light strips extending along the roadside to lead the way.

" Proposals included ‘curvilinear light vessels’ – flexible, scaleable OLED sculptures ranging from reading lamps to outdoor illumination."

The two proposals are poles apart in scale, but both serve to stress the extent to which OLEDs can be integrated into existing materials and environments. "We, as an industry, are still at a relatively early stage of exploring the possibilities," Collon acknowledges. "But I think there is a straight comparison to be made with the development of LEDs; architects started showing a lot of interest in that technology well before it became widely affordable.

"There was plenty of discussion around long-term possibilities and that’s what we’re seeing again now. Pilot projects are well underway, both in the artistic field and smaller interior spaces. We’re seeing that, particularly with organic forms, the shapes and materials into which you can weave this layer of light are endless. OLED technology can certainly enhance and emphasise architecture, but it also has the potential to soften. That is extremely exciting."