OLLA project proposes standard for OLED luminous efficacy measurement

The European OLLA project has released a discussion paper on the measurement of luminous efficacy for OLEDs, with the goal of developing a general standard.

OLLA, the "high brightness Organic LEDs for ICT & next generation Lighting Applications" project funded by the European Union, is hoping to create a standard method for measuring the luminous efficacy of an area light source. A standard methodology should enable comparable measurements to be made by different labs and test houses. OLLA has published a white paper to stimulate discussion, which can be downloaded from the OLLA website.

Importance of efficacy

The efficiency of transforming electrical energy into visible light is one of the crucial parameters for lighting applications. Since 19% of worldwide energy consumption is accounted for lighting applications, there is a clear demand for all lighting technologies to achieve greater efficiency.

Conventional lamp technologies have already derived standards for the measurement of lighting efficiency. However, the field is still open for OLED light sources. “It is very important for a new lighting technology such as OLEDs to have early clear standards defined for its most important light parameters,” says Karsten Diekmann of Osram Opto Semiconductors, co-author of the white paper. "The OLED lamp as a large-area, flat light source bears already a high degree of final luminaire characteristics. Therefore we want to set a standard for its efficacy, so that all early adopters of OLED lighting technology have a good expectation of what light output they can expect”.

In May this year, the OLLA project reported OLEDs with an efficacy of 25 lm/W, which is twice as efficient as a standard incandescent lamp. Several other groups have reported even higher figures, but without mentioning how these figures were measured.

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This article was published in the November/December 2007 issue of LEDs Magazine.

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