Quantum dot white LEDs with high luminous efficiency

Colloidal quantum dots (QDs) have attracted significant attention in the last three decades due to high quantum yield (QY) and tunable electronic properties via quantum confinement effect and material composition. However, their utilization for efficient solid-state lighting sources has remained a challenge due to the decrease of QY from the synthesis batch in the liquid state to the host matrix in the solid state, which is also known as the host material effect. Here, we suppress the host material effect by simple liquid-state integration in light-emitting diodes (LEDs) that lead to a luminous efficiency of 64 lm/W for red, green, blue (RGB)-based and 105 lm/W for green, blue (GB)-based white light generation. For that, we maximized the QY of red- and green-emitting QDs by optimizing synthesis parameters and integrated efficient QDs with QY up to 84% on blue LED dies in liquid form at appropriate injection amounts for high-efficiency white lighting. Liquid-state integration showed two-fold and six-fold enhancement of efficiency in comparison with incorporation of QDs in polydixnethylsiloxane film and close-packed formation, respectively. Our theoretical calculations predicted that the luminous efficiency of liquid QD-LEDs can reach over 200 lm/W. Therefore, this study paves the way toward ultra-high-efficiency QD-based lighting. (C)2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement