title: Solution-processed, high-performance light-emitting diodes based on quantum dots.
abstract: Solution-processed optoelectronic and electronic devices are attractive owing to the potential for low-cost fabrication of large-area devices and the compatibility with lightweight, flexible plastic substrates. Solution-processed light-emitting diodes (LEDs) using conjugated polymers or quantum dots as emitters have attracted great interest over the past two decades. However, the overall performance of solution-processed LEDs--including their efficiency, efficiency roll-off at high current densities, turn-on voltage and lifetime under operational conditions-remains inferior to that of the best vacuum-deposited organic LEDs. Here we report a solution-processed, multilayer quantum-dot-based LED with excellent performance and reproducibility. It exhibits colour-saturated deep-red emission, sub-bandgap turn-on at 1.7 volts, high external quantum efficiencies of up to 20.5 per cent, low efficiency roll-off (up to 15.1 per cent of the external quantum efficiency at 100 mA cm(-2)), and a long operational lifetime of more than 100,000 hours at 100 cd m(-2), making this device the best-performing solution-processed red LED so far, comparable to state-of-the-art vacuum-deposited organic LEDs. This optoelectronic performance is achieved by inserting an insulating layer between the quantum dot layer and the oxide electron-transport layer to optimize charge balance in the device and preserve the superior emissive properties of the quantum dots. We anticipate that our results will be a starting point for further research, leading to high-performance, all-solution-processed quantum-dot-based LEDs ideal for next-generation display and solid-state lighting technologies.
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xingliang
authors.initials: X
authors.lastname: Dai
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Yizheng
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Niu
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
authors.forename: Hujia
authors.initials: H
authors.lastname: Cao
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Liang
authors.affiliation: i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Suzhou 215123, China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Flexible Electronics (KLOFE) &Institute of Advanced Materials (IAM), National Jiangsu Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 211816, China.
authors.forename: Jianpu
authors.initials: J
authors.lastname: Wang
authors.affiliation: Center for Chemistry of High-Performance &Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Peng