Sunlight-style organic light-emitting diodes

We demonstrate organic light-emitting diodes (OLEDs) capable of yielding sunlight-style illumination with various daylight chromaticities, whose color temperature (CT) covers those of the daylight at different times and regions. Besides having the disruptive characters like being plane-type and luminaire-ready, flexible, printable, thin, and light, the emissive spectrum of OLEDs closely resembles that of sunlight. The degree of sunlight spectrum resemblance is 63%, for example, for one high color rendering OLED, while 2% for a sodium lamp, 16% for a fluorescent tube, 49% for a light-emitting diode, and 72% for an incandescent bulb. By incorporating one hole-modulating layer (HML), a fluorescent sunlight-style OLED yields CT between 2300 and 7900 K, while the CT span can be further expanded between 2400 and 18000 K by using double HMLs. For a phosphorescent sunlight-style OLED, the CT spans between 1900 and 3100 K with a power efficiency of 17.6 lm/W at 1000 cd/m(2). (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3583640]