1. Bright colloidal quantum dot light-emitting diodes enabled by efficient chlorination
- Author
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Xiyan Li, Yongbiao Zhao, Min Liu, James Z. Fan, Sjoerd Hoogland, Fengjia Fan, Zheng-Hong Lu, Oleksandr Voznyy, Edward H. Sargent, Li Na Quan, Rafael Quintero-Bermudez, Larissa Levina, Zhenyu Yang, and Xiwen Gong
- Subjects
Brightness ,Materials science ,Passivation ,business.industry ,Halide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantum dot ,law ,Reagent ,Optoelectronics ,0210 nano-technology ,business ,Quantum ,Diode ,Light-emitting diode - Abstract
The external quantum efficiencies of state-of-the-art colloidal quantum dot light-emitting diodes (QLEDs) are now approaching the limit set by the out-coupling efficiency. However, the brightness of these devices is constrained by the use of poorly conducting emitting layers, a consequence of the present-day reliance on long-chain organic capping ligands. Here, we report how conductive and passivating halides can be implemented in Zn chalcogenide-shelled colloidal quantum dots to enable high-brightness green QLEDs. We use a surface management reagent, thionyl chloride (SOCl2), to chlorinate the carboxylic group of oleic acid and graft the surfaces of the colloidal quantum dots with passivating chloride anions. This results in devices with an improved mobility that retain high external quantum efficiencies in the high-injection-current region and also feature a reduced turn-on voltage of 2.5 V. The treated QLEDs operate with a brightness of 460,000 cd m−2, significantly exceeding that of all previously reported solution-processed LEDs. Green light-emitting diodes with a brightness of 460,000 cd m–2 and a low turn-on voltage of 2.5 V are enabled by the use of a chlorination treatment to provide conductive passivation of the devices.
- Published
- 2018