Creation And Sensing Application Of Reduced Okinoglitenyl - Based Novel Field Effect Transistor And Diode

Discovery of graphene in 2004 not only enriched carbon materials but also stimulated the research upsurge in the world. As it is known, graphene is a name given to a flat monolayer (thickness:0.335 nm) of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice. In the 2D materials, the carbon atoms are sp2 hybridized state. Based on its excellent physical and chemical properties such as superior mechanical, electronic and optical properties, graphene has gain great attention and shows potential applications in a variety of fields including but not limited to nano-electronic devices, energy storage materials, catalysts and sensors, etc. Recently, because of low noise, high specific surface area, biocompatibility, sensitive response to certain environmental changes and high thermo-/chemical stability, graphene has been employed as a semi-conductor to construct electronic sensors. In the earlier studies, the graphene-based sensors were created by utilizing the properties of graphene itself. With the development of the research, new strategies such as modification of the graphene surface, optimization of sensor configuration, and variation of sensor preparation processes have been proposed to improve the performances of known graphene-based sensors and create new graphene-based sensors with novel sensing properties.In this thesis, RGO (reduced graphene oxides) is chosen as a sensing element, and the different configurations of liquid electronic sensors demonstrating high sensitivity and selectivity for some biomolecules and metal ions were fabricated. In addition, a flexible gaseous HC1 electronic sensor based on RGO and Ag nanowire (NW) was also created, and the sensor is not only sensitive to the analyte but also selective to the presence of the analyte. The thesis is composed of the following four parts.(1) A micro-patterned RGO based solution-gated field effect transistor (SGFET) sensor was fabricated via a hydrophilic-hydrophobic method, and as expected the transfer curve of the SGFET device exhibits a V-shaped ambipolar field effect behavior from p-type region to n-type region. In order to improve the sensing performance of the device to some nucleoside triphosphates (NTPs), py-dilM-py, which is bipyrene derivative containing a structural moiety with positive charge, was chosen to modify RGO. The modified and unmodified devices were named as S1 and S2, respectively. Sensing performance studies demonstrated that compared to S2, S1 showed improved sensing performance to five NTPs, in particular, GTP and ATP. The detection limit (DL) to GTP and ATP is as low as 400 nM. Sensing mechanism studies revealed that the electrostatic interaction of ATP/GTP with py-dilM-py absorbed on the RGO surface give rise to effective electron transfer from ATP/GTP to RGO. As for the selectivity, it may arise from the strong π-π stacking interaction between the A unit in ATP or G unit in GTP and RGO. Besides, gate voltage, as an important parameter, r not only induces different sensor signals but also modulates the sensor performance. Furthermore, S1 and S2 show cross-reactive responses to the tested five NTPs, and based on the cross reactivity, discrimination of the NTPs was realized by combined use of the two sensors.(2) A novel RGO-based resistant sensor for Hg2+was developed by employing an electrochemical reduction method. Before utilization, the device was modified by using a pyrenyl derivative of glucose (PG) as a modifier. The detection limit (DL) of the modified sensor (C1) to Hg2+ is 0.1 nM, and that of the un-modified one (C2) is 4 nM. Furthermore, the selectivity of C1 was evaluated through examining its responses to common interfering ions, such as K+1 Na+, Cu2+, Zn2+, and Fe3+. Compared with its response to 10 nM of Hg2+, less conductivity change was observed for C1 upon addition of any of the interfering metal ions at a concentration of 100 nM. The simple fabrication method and excellent sensing performances suggest that C1 has the potential to be developed into an integratable Hg2+ detector with idea sensitivity and selectivity.(3) A flexible HCl vapor sensor based on RGO/GO and Ag nanowire (Ag NW) was also fabricated. Alternation of the sedimentary sequence of RGO/GO and Ag NW displaced influence on the sensor conductivity and sensing performance. Sensing tests demonstrated that the sensor detects HCl in vapor state with good sensitivity and specificity. Moreover, the sensing performance of the sensor can be further modulated by optimizing the thickness of the RGO layer.(4) Three novel terthiophene derivatives of cholesterol (TtGC, TtLPC, TtDPC), of which the two building blocks are linked by a structure of glycine, L-phenylalanine or D-phenylalanine, respectively, are designed and prepared (reference appendix), and their gelation behaviors in 26 liquids were tested. Gelation behavior studies demonstrated that the compounds show different gelation abilities with the variation of the linker structures even though the variation is small. FTIR,1H NMR, UV-Vis measurements revealed that intermolecular hydrogen bonding and van der Waals interaction are the main driving forces for the gel formation. AFM and SEM measurements illustrated the evolution process of the morphology of the gel networks formed in the TtDPC/benzene system, which began with left-hand helical small fibers, then larger fibers, then sheets with some fibers, and then sheets with tendons inside, and finally rod-like structures. XRD study indicated that TtDPC in gel state mainly assembled in both a cubic and hexagonal modes. Interestingly, a fluorescent film fabricated by dip-coating TtDPC/benzene onto a glass plate surface is photo-chemically unstable, and it experiences photo-bleaching under UV light in air. However, this UV treated film can be used as a fluorescent turn-on sensor for HAc in vapor state, and the sensing process is fully reversible.To be hnoest, fluorescence films prepared via molecular gels possess a number of advantages such as high porosity, large surface areas, and these properties are favorable for their uses as sensors due to convenient transportation of the analyte within the films and larger interaction sites. However, the films as prepared are not very stable, the preparation and fabrication processes are tedious, and the regeneration of them is difficulty, and thereby the main focus of this thesis was turned to grapheme-based electronic sensors after a number of tries. To ensure the integrity of the thesis, the results from these studies were treated as an appendix...