Polymer as an Additive in the Emitting Layer for High-Performance Quantum Dot Light-Emitting Diodes

• Published in: ACS applied materials & interfaces 2017-06, Vol.9 (23), p.20239-20246
• Main Authors: Liang, Feng, Liu, Yuan, Hu, Yun, Shi, Ying-Li, Liu, Yu-Qiang, Wang, Zhao-Kui, Wang, Xue-Dong, Sun, Bao-Quan, Liao, Liang-Sheng
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b05629

A facile but effective method is proposed to improve the performance of quantum dot light-emitting diodes (QLEDs) by incorporating a polymer, poly­(9-vinlycarbazole) (PVK), as an additive into the CdSe/CdS/ZnS quantum dot (QD) emitting layer (EML). It is found that the charge balance of the device with the PVK-added EML was greatly improved. In addition, the film morphology of the hole-transporting layer (HTL) which is adjacent to the EML, is substantially improved. The surface roughness of the HTL is reduced from 5.87 to 1.38 nm, which promises a good contact between the HTL and the EML, resulting in low leakage current. With the improved charge balance and morphology, a maximum external quantum efficiency (EQE) of 16.8% corresponding to the current efficiency of 19.0 cd/A is achievable in the red QLEDs. The EQE is 1.6 times as high as that (10.5%) of the reference QLED, comprising a pure QD EML. This work demonstrates that incorporating some polymer molecules into the QD EML as additives could be a facile route toward high-performance QLEDs.