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According to the OLED100.eu project, lighting now accounts for a quarter of Europe’s total energy consumption. Development of alternative lighting systems with greater energy efficiency will have an important impact on European energy consumption.
While current low energy and longer-life light bulbs offer energy savings by comparison with incandescent bulbs, they have drawbacks. In particular, hazardous materials, such as mercury, prevents such bulbs from being viable long-term solutions. Fortunately extensive research into low-energy lighting has uncovered new technologies that could revolutionise the sector.
Organic light-emitting diodes (OLEDs)
OLEDs have the potential to increase the energy efficiency of lighting dramatically. The EU-funded OLED100.eu project is striving to produce a lighting system based on OLED technology. Such a system would be twice as efficient as compact fluorescent lighting and eight times more efficient that incandescent bulbs.
Conventional LEDs are already widely used. However, as they produce tiny bright dots of light, they are better suited to spot lighting than area lighting. In contrast, OLEDs produce large glowing surfaces of light, enabling them to illuminate whole rooms.
Traditional incandescent light bulbs create light by passing electricity through a coiled wire, and fluorescent lamps by passing electricity through a gas. OLEDs operate quite differently by running an electrical current through one or more extremely thin layers of organic polymer semiconductors sandwiched between two electrodes. Together they are attached to a transparent substrate material. When a current is applied by the electrodes, it passes through the film, which emits a light. Different colours can be achieved by changing the film material.
FP7 placing spotlight on OLEDs
The OLED100.eu project involves participants from six countries – including lighting specialist Novaled, the University of Gent and multinationals Philips and Siemens – working towards developing this OLED technology for the commercial market. The project is receiving €12.5 million funding through the EU Seventh Framework Programme (FP7).
Before its completion in the summer of 2011, participants hope to have successfully developed a fully operational OLED panel that is twice as efficient and has a longer lifespan than fluorescent tubes. The aim is to reach 100 lumens/W power efficiency, more than 100 000 ‘lifetime hours’, a unit area of 1 m by 1 m and costs of €100 per square metre or less.
The main obstacle preventing widespread commercialisation is that current technology only allows for production of small-scale OLEDs. As the smallest particle of dust can ruin an OLED, the production of large panels is still unfeasible. Moreover, the production of OLEDs, even at a small scale, is quite costly. However, if the 50% saving on electricity bills in the EU, which the project coordinators believe OLEDs could yield, is to be believed, this form of technology is certainly worth investing time and money to develop.
“OLEDs have properties unheard of with other sources,” says project’s coordinator Stefan Grabowski. “One of their most striking features is that you can make them transparent. This means that you can look through the light source when it is off. Therefore designers can integrate OLEDs into windows.”
Novaled is currently developing a thin film encapsulation (TFE) technology which will replace the glass substrates of the OLEDs with a thin flexible multilayer. This will enable the production of flexible and rollable OLED products with a thickness in the micrometer range.
Building on these developments, together with Philips Research, Novaled is also working on fabricating flexible and mouldable OLED panels which could be used for luminous walls, curtains, ceilings and even furniture. Philips Research and Novaled came together to set the world record for the highest power efficiency for a white OLED at 35 lm/W.
Gallium nitride LEDs
While affordable OLEDs may still be some way off, researchers at Cambridge University in the UK have made significant progress in reducing the cost of gallium nitride (GaN) based LEDs. Until now high production costs have made GaN lighting too expensive for widespread use, thus preventing its uptake as a domestic and commercial product. Scientists at the university’s Centre for Gallium Nitride announced in January 2009 that their new approach to producing GaN LEDs could reduce household lighting bills by 75% within five years.
Gallium nitride is a man-made semiconductor that has proved too expensive for widespread production because of low yields. However, Cambridge University’s new approach could reduce costs to a tenth of current levels. This new technique grows GaN on silicon rather than the previously-used sapphire wafers. Such a change is believed to result in a 50% improvement in cost and efficiency.
GaN LEDs can burn for 100 000 hours and do not contain environmentally damaging materials such as mercury. Moreover, they have the added advantages of turning off instantly and being dimmable. Researchers at Cambridge believe GaN lights in every home and office in the UK could cut the proportion of electricity used from 20% to 5%. – equivalent to the output of eight power stations.
The potential of GaN LEDs goes far beyond lighting. Ultraviolet rays produced from GaN lighting could also aid water purification and disease control in developing countries, be used to identify the spread of cancer and help fight hospital ‘super bugs’.
LED use beyond lighting
LEDs can significantly increase energy efficiency in products beyond lighting. LED technology has already greatly increased the efficiency of displays for computers, mobile phones and portable devices. Moreover, LED technology allows for the production of thinner displays with higher performance levels and picture quality. Not only do they require less production steps, in comparison with liquid crystal (LCD) or plasma displays, but they are also more energy efficient as they do not require back lighting.
The world’s largest manufacturer of LCD televisions, Samsung, announced in January 2009 that it would increase the proportion of the TVs its makes using LED technology. These new third generation LED TVs will harness LEDs as their primary light source. In doing so Samsung believe such devices can reduce energy consumption by 40% over traditional LCD display models.
European support for low energy lighting
The EU has recently taken significant steps towards increasing the use of energy saving lamps. In March 2009, it adopted a decision to phase out incandescent lamps by 2012 and low efficiency halogen lamps by 2016. This measure is intended to prompt consumers to switch to energy-saving lighting solutions.
Such a move will reduce energy consumption for domestic lighting by 30% in Europe. As such lighting accounts for 14% of the overall energy used in Europe, an increase in energy-efficient lighting could save more than 80% of the energy used through traditional incandescent light bulbs.
This step by the EU was welcomed by the European Lamp Companies Federation, which called on the European Commission and the European Parliament to go one step further and adopt a dedicated Lighting Design Directive.