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Author: search.filters.author.Inpor, Kroekchai

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    PMMA/High-k Self-assembled TiO2 /PMMA Multi-layer Gate Dielectric for P3HT Organic Field Effect Transistors
    (2022-01-01)
    Inpor, Kroekchai
    ;
    Houngkamhang, Nongluck
    ;
    Thanachayanont, Chanchana
    ;
    Prichanont, Seeroong
    ;
    Kayunkid, Navaphun
    In this work, a multi-layer structure of poly (methyl methacrylate)/ titanium dioxide/poly (methyl methacrylate) (PMMA/TiO₂ /PMMA; PTP) was proposed as a top-gate insulator for P3HT-based organic field-effect transistors (OFETs). Adding a TiO₂ interlayer as a high dielectric constant (high-k) material into PMMA film enables the modification of the dielectric constant of the multi-layers PTP film. The content of TiO₂ in the PTP film, which can be varied by changing the number of soaking cycles in TiO₂ solution, plays a crucial rule in modifying the dielectric constant of the PTP film. The higher the TiO₂ content used in the PTP film, the higher the dielectric constant of PTP film can be obtained. However, using high TiO₂ content led to a reduction in the dielectric constant of the PTP film due to leakage current induced by the agglomeration of TiO₂. The utilization of the top-gate insulator containing TiO₂ significantly enhanced several P3HT-OFETs characteristics, e.g., an increase in the I<inf>on</inf>/I<inf>off</inf> ratio, and a decrease in the threshold voltage. However, the use of the PTP top-gate insulator with a high content of TiO₂ resulted in regressions in the OFETs characteristics, such as a decrease in carrier mobility and reduction in the I<inf>on</inf>/I<inf>off</inf> ratio. OFETs operating at the optimum conditions of the PTP gate-insulator, with PTP thickness of 225 nm and RMS roughness of 20.0 nm, provided a dielectric constant of 7.13, a threshold voltage of-8.49 V, a saturation mobility of 2.2× 10<sup>-4</sup> cm²V<sup>-1</sup>s<sup>-1</sup>, I<inf>on</inf>/I<inf>off</inf> ratio of 37.9, and a subthreshold slope of 0.39 V/decade.
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    Molecularly Imprinted Polymers Near Field Communication sensors for pesticide detection
    (2022-01-01)
    Leepheng, Piyawan
    ;
    Phromyothin, Darinee
    ;
    Thanachayanont, Chanchana
    ;
    Inpor, Kroekchai
    ;
    Olarnwanich, Aricha
    For a healthy and convenient daily lifestyle, co-development of pesticide residue detectors to integrate molecularly imprinted polymers (MIPs) modified electrodes and industrial innovative Near Field Communication (NFC) sensor for smartphones interface devices has been established. It targets cypermethrin and carbaryl which are usually detected in fruits and vegetables. Pesticide-MIPs were fabricated on commercial screen-printed electrodes (SPEs) by bulk polymeri-zation of methyl methacrylate (MMA) monomer, ethylene glycol dimethacrylate (EGDMA) cross-linker, azobis(2-methyl-propionitrile (AIBN) initiator with cypermethrin and carbaryl templates in cypermethrin-MIPs/SPE and carbaryl-MIPs/SPE, respectively. The surface morphology of modified electrodes was characterized by field-emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM), which present cavities of a template on the surface of MIPs/SPE. The experiments of NFC pesticide residue detectors were conducted in real vegetable samples, where a selectivity of 32.18 μA/ppb and a detection limit of 5.4 ppb for cypermethrin-MIPs/SPE and a selectivity of 22.15 μA/ppb and a limit of detection of 9.3 ppb for carbaryl-MIPs/SPE have been obtained. The electrodes can be used four times and have more than six months storage duration.
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