Kang Chengbin, Prodanov Maksym F, Gao Yiyang, Mallem Kumar, Yuan Zhengnan, Vashchenko Valerii V, Srivastava Abhishek K
State Key Laboratory of Advanced Displays and Optoelectronics Technologies, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, China.
Centre for Display Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, China.
Adv Mater. 2021 Dec;33(49):e2104685. doi: 10.1002/adma.202104685. Epub 2021 Oct 10.
Efficient white light-emitting diodes (LEDs) with an efficacy of 200 lm W are much desirable for lighting and displays. The phosphor-based LEDs in use today for display applications offer poor color saturation. Intensive efforts have been made to replace the phosphor with quantum-dot-based downconverters, but the efficiency and stability of these devices are still in their infancy. Quantum rods (QRs), nanoparticles with an elongated shape, show superior properties such as relatively larger Stokes shifts, polarized emission, and high light out-coupling efficiency in the solid-state. However, these QRs usually suffer from poor optical quality for PL wavelengths < 550 nm. Herein, a gradient alloyed CdSe/Zn Cd S/ZnS and CdSe/CdS/ZnS core/shell/shell QR downconverters showing high efficacy LEDs covering a wide color gamut are reported. These QRs show high stability and a precisely tunable photoluminescence peak. The engineered shell thickness suppresses energy transfer and thus maintains the high quantum yield in the solid-state (81%). These QR-based LEDs attain an efficacy of 149 lm W (@10mA) and wide color gamut (118% NTSC), which is exceedingly higher than state-of-the-art quantum dots and phosphor-based on-chip LEDs.
效率为200 lm/W的高效白光发光二极管（LED）在照明和显示领域非常受欢迎。目前用于显示应用的基于磷光体的LED颜色饱和度较差。人们已经做出了大量努力，用基于量子点的下转换材料取代磷光体，但这些器件的效率和稳定性仍处于起步阶段。量子棒（QR）是一种具有细长形状的纳米颗粒，在固态中表现出优异的性能，如相对较大的斯托克斯位移、偏振发射和高光出耦合效率。然而，这些量子棒对于PL波长<550 nm的光学质量通常较差。在此，报道了一种梯度合金化的CdSe/ZnCdS/ZnS和CdSe/CdS/ZnS核/壳/壳量子棒下转换材料，其展示了具有高功效且覆盖宽色域的LED。这些量子棒具有高稳定性和精确可调的光致发光峰。经过设计的壳层厚度抑制了能量转移，从而在固态中保持了高量子产率（81%）。这些基于量子棒的LED实现了149 lm/W（@10 mA）的功效和宽色域（118% NTSC），这比最先进的量子点和基于磷光体的片上LED要高得多。
