This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on amixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standardCe:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in theemission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one tomove the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased lightabsorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issuetoday for LED-based lighting.Using photoluminescence of Lumogen® F Yellow 083, a perylene-based polymer dye commercialized by BASF, andadding a small quantity of another perylene-based dye, Lumogen® F Red 305 (BASF), we obtained high-efficiencywarm white LEDs by yellow and red conversion from a standard 450 nm GaN/InGaN royal blue LED. Different weightproportions of dyes were dissolved in solutions with equal amounts of poly-methyl-methacrylate (PMMA) in ethylacetate, then the LEDs were dip-coated in each solution and optically characterized. Record values of 8.03 lm ofluminous flux and 116.11 lm/W of optical efficiency were achieved.Finally, the effects of both driving current, and pump wavelength on LED performances – such as chromatic coordinates,correlated color temperature, color rendering index (CRI), and optical efficiency – were investigated.
|Titolo della pubblicazione ospite||Integrated Photonics: Materials, Devices, and Applications II|
|Numero di pagine||10|
|Stato di pubblicazione||Published - 2013|
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