White organic LED

BASF and Osram Opto Semiconductors have developed a white organic light-emitting diode (OLED).

For the first time, it is claimed, an OLED can not only achieve a light yield of more than 60 lumens per W, but also meet the International Energy Star SSL Standard with regard to colour.

Lighting efficiency describes the ratio of luminous flux given off by a lamp to the amount of power consumed; the greater the yield, the less energy is lost.

Although this efficiency has been achieved, until now the colour values of OLEDs have not been within the acceptable band for colour coordinates around the Planck curve.

The OLEDs contain phosphorescent metal complexes as emitter materials and customised complementary materials, which ensure optimum constancy of the colour temperatures. The use of new materials ensures the diodes are colour stable even when there are variations in luminous intensity.

The challenge now is to optimise the life of these OLED files, especially by stabilising the blue emitters.

Laboratory results show that the devices are five times more efficient than filament bulbs and up to 50% more efficient compared with standard low-energy lamps.