Rosin-enabled ultraclean and damage-free transfer of graphene for large-area flexible organic light-emitting diodes

Zhikun Zhang,Hengda Sun,Dingdong Zhang,Dongge Ma,Lichang Yin,Jiangshan Chen,Jinhong Du,Hui-Ming Cheng,Laipeng Ma,Wencai Ren

doi:10.1038/ncomms14560

Abstract

The large polymer particle residue generated during the transfer process of graphene grown by chemical vapour deposition is a critical issue that limits its use in large-area thin-film devices such as organic light-emitting diodes. The available lighting areas of the graphene-based organic light-emitting diodes reported so far are usually <1 cm2. Here we report a transfer method using rosin as a support layer, whose weak interaction with graphene, good solubility and sufficient strength enable ultraclean and damage-free transfer. The transferred graphene has a low surface roughness with an occasional maximum residue height of about 15 nm and a uniform sheet resistance of 560 Ω per square with about 1% deviation over a large area. Such clean, damage-free graphene has produced the four-inch monolithic flexible graphene-based organic light-emitting diode with a high brightness of about 10,000 cd m−2 that can already satisfy the requirements for lighting sources and displays.

Highlights

The large polymer particle residue generated during the transfer process of graphene grown by chemical vapour deposition is a critical issue that limits its use in large-area thin-film devices such as organic light-emitting diodes
Graphene is a promising material for a wide range of applications especially in next-generation flexible thin-film electronic and optoelectronic devices[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19], such as organic light-emitting diodes (OLEDs)[12,13,14], and organic photovoltaic (OPV) cells[15,16,17,18,19], because of its twodimensional (2D) structure, excellent electrical conductivity, high transparency, extremely high mechanical strength, good flexibility and chemical stability[20,21,22]
As discussed in Supplementary Note 2 and shown in Supplementary Table 3, it has a good solubility in commonlyused organic solvents such as alcohol, ether, acetone and chloroform

Summary

Introduction

The large polymer particle residue generated during the transfer process of graphene grown by chemical vapour deposition is a critical issue that limits its use in large-area thin-film devices such as organic light-emitting diodes. The transferred graphene has a low surface roughness with an occasional maximum residue height of about 15 nm and a uniform sheet resistance of 560 O per square with about 1% deviation over a large area Such clean, damage-free graphene has produced the four-inch monolithic flexible graphene-based organic light-emitting diode with a high brightness of about 10,000 cd m À 2 that can already satisfy the requirements for lighting sources and displays. The damages and, in particular, polymer residues introduced during transfer degrade the optical and electrical properties of graphene and generate a large surface roughness[41], which may greatly limit the application of graphene in large-area thin-film devices such as OLEDs and OPV cells. We have found that rosin (C19H29COOH), a small natural organic molecule, is a very good support layer for the a c

Methods

Results

Conclusion