Novaled announced that it has developed a new efficient (36 lm/W) fluorescent white OLED, which the company claims is the world's most power efficient white OLED structure. Novaled used their own proprietary organic materials and a new flat light outcoupling method of extraction and achieved an increase in light emission by more than 80%, with good color rendering. Novaled's new structure also has an improved light angular dependence.
Here's more technical info from Novaled's press release:
Novaled’s novel methods boost outcoupling effectiveness, substantially increasing the 25-35 percent fraction of generated light that typically leaves the OLED device for lighting applications. They also increase power efficiency and quantum efficiency in both bottom- and top-emission OLEDs. In bottom-emission OLEDs Novaled incorporates the material NET61 directly inside the electron transport layers. The combination of NET61 internal outcoupling and an external micro lens array (MLA) film boosts power efficiency by more than 70-percent and quantum efficiency by more than 80-percent. In top-emission OLEDs, Novaled uses scattering material NLE17 on top of the semi-transparent top electrode to help extract light and improve the quality of light emitted from top-emission white OLED devices.
Novaled’s new outcoupling techniques use standard processes to produce the white PIN OLED device structures, thus reducing manufacturing costs for both bottom-emission and top-emission OLEDs. Unlike other outcoupling enhancement approaches in bottom-emission OLEDs such as depositing complicated structured layers between substrate glass and the indium tin oxide (ITO) anode Novaled uses simple internal outcoupling methods with vacuum evaporation processed organic materials to induce scattering of the light emitted by the OLED. In both bottom- and top-emission OLEDs, the scattering does not negatively impact electrical properties.
In addition, Novaled’s new method improves the Color Rendering Index (CRI) value for top-emission OLEDs on metal substrates. Although top-emission samples on metal substrates with a white light emission typically have stronger cavity effects than bottom-emission devices and show strong variations with the viewing angle, Novaled increases light extraction from top-emission white OLEDs and strongly reduces angular color dependence by using a scattering evaporation processed organic layer on top of the semi-transparent top electrode. Novaled’s demonstrated CRI of 75 for top-emission OLEDs is ample for many commercial lighting applications.
