No abstract

Solution-processable molecular hole transporting materials (HTMs) are crucial to realize inexpensive fabrication of energy-efficient and large area organic light emitting diodes (OLEDs) for next-generation displays and lighting.

Increasing studies report blue light to possess a potential hazard to the retina of human eyes, secretion of melatonin and artworks. To devise a human- and artwork-friendly light source and to also trigger a "Lighting Renaissance", we demonstrate here how to enable a quality, blue-hazard free general lighting source on the basis of low color-temperature organic light emitting diodes. With the use of multiple candlelight complementary emitters, the sensationally warm candle light-style emission is proven to be also drivable by electricity. To be energy-saving, highly efficient candle-light emission is demanded. The device shows, at 100 cd m^-2 for example, an efficacy of 85.4 lm W^-1, an external quantum efficiency of 27.4%, with a 79 spectrum resemblance index and 2,279 K color temperature. The high efficiency may be attributed to the candlelight emitting dyes with a high quantum yield, and the host molecules facilitating an effective host-to-guest energy transfer, as well as effective carrier injection balance.

Yellow emission plays an important role in many display and lighting applications, such as RGBY display or blue hazard free lighting sources, while a wet-process enables soft devices to be manufactured cost-effectively.

Wet-process feasible high triplet energy carbazole type host materials are synthesized. On doping a green emitter into a host carbazole, the device shows an efficacy of 51 lm W¬1 and current efficiency of 52 cd A¬1 at 100 cd m−2.