Abstract
We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm2·V−1·s−1), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.
Highlights
Graphene is a two-dimensional monolayer of carbon atoms that has outstanding mechanical, chemical and electrical properties[1,2,3,4,5,6]
We demonstrated an organic field-effect transistor (OFET) as the first example of organic electronic devices using graphene electrodes based on direct patterned growth from solid carbon source on the device substrate without using any additional graphene-transfer process; the Ni capping layer was removed by wet etching, thereby leaving the graphene films on SiO2/Si substrate
The samples were thermally annealed in a furnace under Ar (50 sccm) and H2 (10 sccm) gas, and low vacuum (~330 mTorr) at 900–1100 °C for 1–4 min to find the optimal conditions for graphene synthesis
Summary
Graphene is a two-dimensional monolayer of carbon atoms that has outstanding mechanical, chemical and electrical properties[1,2,3,4,5,6]. Among existing methods to obtain large, high-quality graphene layers, epitaxial approaches use substrates such as SiC to guide direct growth of graphene[7,8,9,10]. Steelworks produce a huge amount of CTP, which is toxic and causes severe environmental problems[49] Recycling of this low-cost waste into high-added-value materials such as graphene could contribute greatly to environmental cleanliness and sustainable production of graphene. We demonstrated an organic field-effect transistor (OFET) as the first example of organic electronic devices using graphene electrodes based on direct patterned growth from solid carbon source on the device substrate without using any additional graphene-transfer process; the Ni capping layer was removed by wet etching, thereby leaving the graphene films on SiO2/Si substrate
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