Quantum dot light-emitting diodes using a graphene oxide/PEDOT:PSS bilayer as hole injection layerElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ra07948f

• Main Authors: Song, Dae-Ho, Song, Suk-Ho, Shen, Tian-Zi, Lee, Jun-Seo, Park, Won-Hyeok, Kim, Sang-Soo, Song, Jang-Kun
• Format: Journal Article
• Language: English
• Published: 07.09.2017
• ISSN: 2046-2069
• DOI: 10.1039/c7ra07948f

Quantum dot (QD) light-emitting diode (QLED) displays are highly promising optoelectronic devices, but several critical issues remain to be solved. The hole-electron charge balance is particularly important but hole-injection is more difficult than electron-injection in QLEDs; as a result, good hole injection ability is required. Here, we introduce a graphene oxide (GO) layer between the anode electrode and a typical hole injection layer of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) to improve the hole injection ability of a QLED device. The device with the GO/PEDOT:PSS bilayer hole injection layer exhibits a three-fold increase in brightness and external quantum efficiency as well as doubled current efficiency compared to a counterpart device using a single PEDOT:PSS layer. In addition, the turn-on voltage is improved from 8.35 V to 5.35 V. The dramatic improvements in the optoelectronic performance are attributed to the stepwise energy band structure in the hole injection bilayers; the work function of the GO layer is measured to be 4.98 eV, which reduces the interfacial barrier energy between the anode and PEDOT:PSS layer. Adoption of graphene oxide/PEDOT:PSS as a HIL layer dramatically improves the electro-optical performance of QLED devices.