A conventional bulb converts the most of the consumed electric energy into heat. For that reason it has been replaced to large extent by the LED lamps. These are considerably more energy efficient and have a higher light output and longer life time. They are well established in the room lighting and are widely used in the ambient light. But LED’s are a spot lights source and therefore reach their limits, if a large area diffuse light is required.
A suitable solution should be organic LED’s, so called OLED’s. They are produced using the thin-film technology. An organic semiconducting layer is applied onto a substrate. The system is then sealed off, as it is extremely sensitive to moisture. Plastics can be used only partially as barrier, as sooner or later water molecules will penetrate the plastics. Glass is a safe encapsulation material, but it is not flexible. Flexible glass is being developed currently. Only small areas with low bending radii are today available. In the moment large OLED’s are very expensive and have a short life time. In consumer electronics the technology, has already gained a foothold however. For large-area ambient lighting OLED’s are not ready yet.
In contrast the reasinably priced electroluminescent systems such as Glow-Tec® are increasingly entering the lighting market. EL – films have a similar structure to OLED’s, but they use inorganic phosphors instead of organic ones. These are less sensitive to moisture, so that plastics can be used as a substrate material. Even an encapsulation is not always necessary. If the electroluminescent systems are regularly taken into operation, the current passing through can drive out the moisture. If necessary, the EL films can be easily protected against the environmental influences by lamination.
The significant advantage is its flexibility. The systems can be applied directly onto other objects, e. g. furniture or walls. Widths up to one meter and various lengths are possible with Glow-Tec®. The EL – systems are more robust than the OLED’s and also have a lower price. Even if larger amounts of moisture will enter the system, it will not be destroyed. In this case, the luminance decreases significantly and the lighting area will have a shade. In consequencethe system should be run with lower voltage for some time, thus the absorbed moisture can be driven out of the system. Then standard conditions could be applied again.
Another crucial advantage of the Glow-Tec® is the option to tailor it freely. The system can be cut in almost every shape with a simple pair of scissors. The following image shows a tailored company logo of the Glow-Tec® manufacturer InovisCoat GmbH.
Glow-Tec® is being continuously optimized and developed. New colors are soon expected: a strong red and a clear white.