Large Area Graphene on Polymer Films for Transparent and Flexible Field Emission Device
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Large Area Graphene on Polymer Films for Transparent and Flexible Field Emission Device Ved Prakash Verma, Santanu Das, Indranil Lahiri and WonBong Choi Department of Mechanical and Materials Engineering, Florida International University, Miami, Florida 33174, U.S.A. ABSTRACT Large scale fabrication of graphene over transparent flexible polymer, Polyethelyne tetrapthalate (PET), and its application in flexible field emission display is reported here. We used Cu foil (~160 mm x 60 mm) to grow graphene by thermal chemical vapor deposition process and transfer the graphene over a polymer using a straightforward hot press lamination technique. The fabrication method is facile as there is no rigorous chemical process involved and the process is also applicable towards the fabrication of large scale graphene over a wide range of transparent flexible substrates for foldable micro-electronics applications. Further, we demonstrate the application of graphene/PET polymer film as anode of transparent flexible field emission display device. The device shows low turn-on voltage ~ 1.75V/μm and high current density of ~ 65μA/cm2 with field enhancement factor (β) ~1000. INTRODUCTION Recently graphene creates a lot more attraction of scientists and researchers due to its excellent thermal, electrical and optical conductivity along with high mechanical strength [1-3]. So far, people have proposed and demonstrated several emerging applications of graphene as transistors, interconnects, supercapacitors, gas sensors and flexible displays [4-8]. Outstanding optical transmittance emerges with the good electrical conductivity and high mechanical strength make graphene as a potential alternative of Indium tin Oxide (ITO) for future foldable electronics [9]. The major disadvantages of ITOs are its limit in flexibility, high cost and less transparency in the infra red (IR) region. On the other hand, graphene is good in mechanical strength as well as exhibit >85% transparency in the entire IR region, hence can be used as IR sensors as well [10]. The challenge at this moment is to fabricate large scale graphene as flexible transparent conducting film. Several reports have been found where people used the solution of graphene flakes or chemically derived graphene (or graphene oxide) and spin coat it on different flexible substrates in order to fabricate the graphene transparent conducting film [11,12]. However, the homogeneity of the films is not up to the mark due to the presence of inhomogeneous reduced graphene oxide flakes [12]. In particular, for applications in the display devices, the transparent conducting film must be homogeneously transparent throughout the substrate. Another interesting technique was demonstrated for transferring graphene on flexible transparent substrate by stamping and scooping method [7]. However, the method introduces imperfection on the graphene film during large scale transfer process and ineffective for large scale production. Here we demonstrate an effective and affable process for large area graphene transfer
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