Ultrahighly Efficient White Quantum Dot Light-Emitting Diodes Operating at Low Voltage

Achieving efficient white quantum dot light-emitting diodes (WQLEDs) is highly desired because of their promising applications in general illumination and display backlight systems. Herein, a highly efficient WQLED with an extremely low input voltage is reported, which is fabricated via an all-solution process by using an emitting layer with a mixture of red-, blue-, and green-emitting quantum dots. When a facile strategy of light outcoupling with an optical lens is introduced, the device shows a maximum external quantum efficiency of 28.4%, which is the highest value reported so far. Moreover, the device exhibits a standard white emission with International Commission on Illumination (CIE) coordinates of (0.36, 0.34) at an extremely low input voltage of 3.2 V. This work provides a promising way for achieving high-performance white quantum-dot light-emitting diodes with low driving voltage.