High Efficiency Color-Temperature Tunable Organic Light-Emitting Diode
Rhythmic lighting with varying color and brightness like that of the diurnal sunlight has now been recognized to be extremely crucial to human health. In this study, we demonstrate a high-efficiency and high light-quality organic light-emitting diode (OLED) with color temperature tunable from the 1,700K of dusk-hue, 1,900K of candles and 2,500K of incandescent bulbs to 3,000K of warm-white light. The color-temperature tunable OLED device was achieved by utilizing a hybrid system and inserting a carrier modulation layer (CML) between the emission layers. In addition, electron-rich charge transport property of EML-1, facilitated via a 3:1 composition ratio of the 3P-T2T host to TPD-15 co-host, played a crucial role in tuning the desirable low-color temperature of the fabricated OLED devices. The current efficacy, power efficacy, and spectrum resemblance index (SRI) of the studied OLED are 40.2 cd/A, 40.3 lm/W and 82.2 at 1,000 cd/m2, respectively. The resultant devices show great potential to advance the study and development of physiologically friendly lighting and enable a successful commercial OLED lighting product in the market.