Ultrathin flexible graphene films with high thermal conductivity and excellent EMI shielding performance using large-sized graphene oxide flakes.

Shaofeng Lin,Su Ju,Gang Shi,Dazhi Jiang,Jianwei Zhang,Yonglyu He

doi:10.1039/c8ra09376h

Shaofeng Lin, Su Ju + Show 4 more

Open Access

https://doi.org/10.1039/c8ra09376h

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Journal: RSC advances	Publication Date: Jan 1, 2019
Citations: 48	License type: CC BY 3.0

Affiliation: National University of Defense Technology

Abstract

As the demand for wearable and foldable electronic devices increases rapidly, ultrathin and flexible thermal conducting films with exceptional electromagnetic interference (EMI) shielding effectiveness (SE) are greatly needed. Large-sized graphene oxide flakes and thermal treatment were employed to fabricate lightweight, flexible and highly conductive graphene films. Compared to graphene films made of smaller-sized flakes, the graphene film made of large-sized flakes possesses less defects and more conjugated domains, leading to higher electrical and higher thermal conductivities, as well as higher EMI SE. By compressing four-layer porous graphene films together, a 14 μm-thick graphene film (LG-4) was obtained, possessing EMI SE of 73.7 dB and the specific SE divided by thickness (SSE/t) of 25 680 dB cm2 g−1. The ultrahigh EMI shielding property of the LG-4 film originates from the excellent electrical conductivity (6740 S cm−1), as well as multi-layer structure composed of graphene laminates and insulated air pores. Moreover, the LG-4 film shows excellent flexibility and high thermal conductivity (803.1 W m−1 K−1), indicating that the film is a promising candidate for lightweight, flexible thermal conducting film with exceptional EMI shielding performance.

Highlights

With the rapid development of information technology in recent years, electromagnetic (EM) pollution caused by electronic components of wearable and foldable equipments, such as exible electrodes, storage devices, and smart sensors,[1,2,3] has became a serious environmental issue
For the portion of waves able to enter shielding materials, absorption loss is the dominant consumption of this EM energy, which depends on the interaction between conducting parts of shielding materials and EM waves.[7,9,10]
Thickness of the LG-8 lm is measured by the micrometer, which is in good agreement with that determined by SEM images (Fig. 2i and j)

Summary

Introduction

With the rapid development of information technology in recent years, electromagnetic (EM) pollution caused by electronic components of wearable and foldable equipments, such as exible electrodes, storage devices, and smart sensors,[1,2,3] has became a serious environmental issue. The results demonstrate that larger-sized graphene akes has less oxygenated groups and fewer defects, which might lead to higher electrical conductivity and better EMI shielding performance.

Results

Conclusion