Sunlight-like, color-temperature tunable white organic light-emitting diode with high color rendering index for solid-state lighting application

A high color rendering index (CRI) is crucial for organic light-emitting diode (OLED) which can be applied in high-quality lighting sources. We have developed three types of white OLEDs with two-, three- and four-peak electroluminescence spectra. For two-peak OLED, a luminance efficiency of 34.59 cd A(-1) at 100 cd m(-2) with a CRI of 45 is obtained. For three-peak OLED, CRI above 85 and a maximum luminance efficiency of 27.29 cd A(-1) are realized. Four-peak OLED yields color-temperature tunable white emission in the luminance range of 100 cd m(-2) to 5000 cd m(-2), a sunlight-like spectrum with a CRI of 89 at 5000 cd m(-2). The wide color-temperature span of the four-peak OLED could meet the requirements for lighting in dwellings.