Poly(3,4-ethylenedioxythiophene) (PEDOT)-based film has relatively high conductivity, flexibility, and transmittance. However, the improvement for mechanical strength and conductivity is still required to be adopted for commercial applications. Graphene, a one atom thick planar sheet of sp(2)-bonded carbon atoms, is considered as an ideal nanocomposite material for these purposes. In this study, we have developed PEDOT and graphene composite films, two-layered graphene/PEDOT and three-layered graphene/PEDOT/graphene, by using a spin-coating method. The conductivity of a 32 nm thick PEDOT film was improved more than twice by graphene deposition, while the high transmittance of the composite film was maintained over 90%. The mechanical strength of the PEDOT and graphene composite film shows 6-fold enhancement over the pristine PEDOT film. Because of the contribution of graphene layer for enhancing the mechanical strength, a 44 nm thick graphene/PEDOT/graphene could be obtained as a free-standing film by delaminating the graphene layer from the glass substrate under a weak base solution. These results imply that the graphene not only improves the conductivity and mechanical strength of PEDOT but also enables to produce a free-standing film which could find a variety of applications in the fields of organic electronic, sensors, and optoelectronics.

A graphene based biosensor system is presented for performing highly sensitive pathogenic virus detection. A free-standing conductive graphene film was prepared as a novel electrochemical sensor through two steps: synthesis of a graphene oxide (GO) film from GO colloidal suspensions by using a speed vacuum concentrator and thermal annealing process at 900� C with H 2 /Ar flow to generate a reduced GO film. The resultant graphene film shows an excellent electron transfer property on the surface in the [Fe(CN) 6 ] 3-/ 4-redox system and is used as a working electrode in the electrochemical biosensor. The surface of graphene is modified with pyrene derivatives, and then covalently linked with virus-specific antibodies. The target cell, rotavirus, is captured on the graphene film through antibody-antigen interaction, and the entire process was monitored by cyclic voltammetric responses. A 10 5 pfu/mL of input cells is detected with ca. 30.7% sensitivity, and ca. 1.3% sensitivity is measured with 10 3 pfu/mL of input cells, demonstrating that graphene film based electrode can be applied for electrochemical biosensor.

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This study examined how green technology (GT) has evolved recently in the domain of national research and development (R&D) in Korea. The analysis considered social network analysis by using keywords of national R&D projects in environmentally benign ('green' in this paper) technologies. Data for analysis were collected from the R&D database of the National Science and Technology Information Service (NTIS). By selecting the official GT category in the NTIS's database, we gathered 53,896 GT R&D projects from 2011 to 2016 inclusive. By constructing a co-occurrence matrix with keywords, we conducted a centrality analysis (including degree, closeness, betweenness centrality) and visualized the network matrix to display a cluster map. This study presents the following findings: (1) the chronical trends of GT R&D, (2) focused fields of GT R&D, (3) the relations between keywords and GTs, and (4) the characteristics and problems in GT R&D. The paper ends with suggested policy implications to boost national GT R&D and to develop GTs in the future.