High efficiency color-temperature tunable organic light-emitting diode
Rhythmic lighting with varying color-temperature and brightness like that of 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 1700 K of dusk-hue, 1900 K of candles and 2500 K of incandescent bulbs to 3000 K 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, the electron-rich charge transport properties 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 efficiency, power efficacy, and spectrum resemblance index (SRI) of the studied OLED are 40.2 cd/A, 40.3 lm W−1 and 82.2 at 1000 cd m−2, 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.