Solution processed high-efficiency low color temperature organic light emitting diodes and related materials

Low Correlated Color Temperature (CCT) light sources are preferred for physiologically-friendly illumination due to their low suppression of melatonin secretion, and high power efficiency is important in energy-saving applications, too. We fabricated low-CCT white organic light-emitting diodes (WOLEDs) from three and four basic phosphors by spin coating method using a single emission layer. The best device fabricated shows a CT less than 2 500 K and CRI of 83 in a brightness of about 100-10 000 cd/m². Moreover, these devices exhibit a current efficiency of 13.4 cd/A at 100 cd/m² or 17.8 cd/A at 1 000 cd/m², which is comparable with incandescent bulbs. The high performance, solution processable and physiologically-friendly OLED can be an ideal candidate for a light source designed to safeguard human health, especially at night.