Researchers from Taiwan's National Tsing Hua University developed a candlelight-style OLED lighting panel - with a low (1900K) color temperature. To create this device they used four organic electrophosphorescent dyes (red, yellow, green, and sky-blue) that create two emissive layers (blue and orange).
The researchers explain that high color temperature can drastically suppress the generation of melatonin (MLT), a naturally occurring hormone (normally produced at night) that is important for the regulation of the body's circadian rhythms. They say that medical experts have called for the development of new lighting sources with low color temperatures, free of blue emission. Currently no electrical lighting device exists with a color temperature below 2000K. The lowest color temperature is around 2500K for incandescent bulbs. A candle has a temperature of 1910K at its brightest spot.
