We demonstrate a man-made lighting device of organic light-emitting diode (OLED) capable of yielding a sunlight-style illumination with various daylight chromaticities, whose color temperature ranges between 2300 and 8200 K, fully covering those of the entire daylight at different times and regions. The OLED employs a device architecture capable of simultaneously generating all the emissions required to form a series of daylight chromaticities. The wide color-temperature span may be attributed to that the recombination core therein can easily be shifted along the different emissive zones simply by varying the applied voltage via the use of a thin carrier-modulating layer.

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This study reports the fabrication of a highly efficient, very high color-rendering index (CRI) white organic light-emitting diode (OLED) using five organic dyes doped into two different phosphorescent and fluorescent emissive layers separated by a high tripletenergy interlayer. The resulting white OLED achieves a 93 CRI with a power efficiency of 23.3 lm W À1 at 100 cd m À2 , or 14.3 lm W À1 at 1000 cd m À2 . This high CRI is attributable to the five dyes employed in this design, which together emit a relatively wide spectrum that nearly covers the entire range of visible light. At the proper thickness, the interlayer enables the device to balance the distribution of carriers in the two emissive zones and achieve a maximum power efficiency while maintaining high CRI.

We demonstrate an efficient orange-red organic light-emitting diode using a host, 2,7-bis(carbazo-9-yl)-9,9-ditolyfluorene, doped with tris(2-phenylquinoline) iridium(III). The device exhibits a high current efficiency of 44.8 cd/A at 1000 cd/m2. This may be attributed to the adoption of the host, which favors the injection of holes, as well as the emissive-layer architecture enabling excitons to form on host and hence favoring efficient energy-transfer from host to guest. Moreover, an electron-confining layer is used to modulate excessive holes to be injected into emissive layer and confine the electrons, which would in turn balance the injection of both carriers and improve efficiency.