Bright, efficient, and color-stable violet ZnSe-based quantum dot light-emitting diodes

• Published in: Nanoscale Vol. 7; no. 7; pp. 2951 - 2959
• Main Authors: Wang, Aqiang, Shen, Huaibin, Zang, Shuaipu, Lin, Qingli, Wang, Hongzhe, Qian, Lei, Niu, Jinzhong, Song Li, Lin
• Format: Journal Article
• Language: English
• Published: England 21.02.2015
• Subjects: Cadmium; Light-emitting diodes; Lighting; Luminance; Nanostructure; Quantum dots; Shells; Zinc selenides; Zinc sulfides
• ISSN: 2040-3364; 2040-3372; 2040-3372
• DOI: 10.1039/C4NR06593J

In this paper, highly stable violet-blue emitting ZnSe/ZnS core/shell QDs have been synthesized by a novel “low temperature injection and high temperature growth” method. The resulting nearly monodisperse ZnSe/ZnS core/shell QDs exhibit excellent characteristics such as a high color saturation (typical spectral full width at half-maximum between 12 and 20 nm), good emission tunability in the violet-blue range of wavelengths from 400 to 455 nm, a high absolute PL quantum yield (up to 83%), and superior chemical and photochemical stability. By employing ZnSe/ZnS core/shell quantum dots (QDs) as emitters with a fully solution processable method, bright, efficient, and color-stable violet Cd-free quantum dot-based light-emitting diodes (QD-LEDs) with maximum luminance up to 2632 cd m −2 and a peak EQE of 7.83% have been demonstrated successfully. Considering the factors of the photopic luminosity function, the brightness and efficiency results of such violet QD-LEDs not only represent a 12-fold increase in device efficiency and an extraordinary 100 times increase in luminance compared with previous Cd-free QD-LEDs but also can be much superior to the best performance (1.7%) of their Cd-based violet counterparts. These results demonstrate significant progress in short-wavelength QD-LEDs and shed light on the acceleration of commercial application of environmentally-friendly violet QD-based displays and lighting.