Hybrid remote phosphors for white LEDs : combining quantum dots and rare earth doped phosphors

Current white LEDs (wLEDs) are composed of a blue pumping LED and color convertors – phosphors – which are typically rare earth doped inorganic materials. As backlight in displays these wLEDs often have the disadvantage that a substantial fraction of the emitted light needs to be filtered out. In general lighting, efficiency losses are often generated by an emission extending into the infrared region, while also color rendering can be suboptimal. Recently, the use of quantum dots (QDs) as color convertor materials in wLEDs has gained attention as a solution to these problems. Here, we discuss our recent research results to improve performance and cost-efficiency of wLEDs for display and lighting applications. We develop and implement color convertor materials in a remote phosphor configuration, thereby improving efficiency, (color) homogeneity and stability compared to conventional phosphor-on-LED-chip designs. We explore the use of hybrid phosphor layers, consis ting of a combination of rare earth doped phosphors with CdSe, chalcopyrite or InP-based QDs. We provide synthesis strategies to obtain the required QDs and configurations to implement them in a polymer-based remote phosphor layer, of which scattering and self-absorption is discussed. Finally, we show relevant characteristics of a benchmark wLED device.

Publication year:2015