Organic field effect transistor with a novel poly(linoleic acid)-g-poly(methyl methacrylate)-g-poly(D,L-lactide) graft copolymer insulator using a PEDOT:PSS composite electrode

This study presents a one-pot process used to synthesize novel poly(linoleic acid)-g-poly(methyl methacrylate)-g-poly(D,L-lactide) (PLina-g-PMMA-g-PLA (PLiMALA-3)) graft copolymers. The process was carried out by combining the free radical polymerization (FRP) of methyl methacrylate with the ring-opening polymerization (ROP) of D,L-lactide from polymeric linolenic acid having peroxide groups in the main chain. The characterization of the graft copolymers was performed using proton nuclear magnetic resonance, gel permeation chromatography, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. Afterwards, an organic field effect transistor (OFET) was fabricated with the novel poly(linoleic acid)-g-poly(methyl methacrylate)-g-poly(D,L-lactide) graft copolymer (PLiMALA-3) as the insulator layer. Poly(3-hexylthiophene) (P3HT) was used as the active layer and pre-patterned OFET substrates were used as the source/drain electrodes. In order to measure capacitance, an ITO/(PLiMALA-3)/PEDOT:PSS structure was prepared using the same method. For electrical characterization of the OFET, the device was held in the dark at room temperature in ambient air in order to determine the characteristics of the output and transfer current–voltage (I-V). The main parameters of the device, which included the threshold voltage (VTh), field effect mobility (?FET) and current on/off ratio (Ion/Ioff), were determined by measuring the capacitance–frequency (C–f) plot of the ITO/Polymer/PEDOT:PSS structure. Results showed that the fabricated OFET device exhibited good performance including low VTh, comparable mobility and Ion/Ioff. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.2015.05.03.381, 2018.05.03.681, 2018.05.03.674Acknowledgements This work was supported financially by Düzce University Research Fund (Grant Numbers: 2015.05.03.381, 2016.05.03.468, 2018.05.03.681, 2018.05.03.674)

Comparative investigation of electronic parameters of low voltage organic field-effect transistors with variable capacitance non-ionic gel gate dielectrics

Non-ionic gel dielectrics (NIGDs) have high effective capacitances (CEFF) which can be used to reduce the operating voltage of the organic field-effect transistors (OFETs). Limited work has been carried out about these kinds of dielectrics although they have advantages of low cost and easy production. Besides, by mixing propylene carbonate (PC) with various kinds of polymers in order to tune the CEFF of the blend, electronic parameter performance of the OFETs can be improved. In this study, regioregular poly(3-hexylthiophene-2,5-diyl) (rr-P3HT) based OFETs were fabricated. Specifying the poly(methyl-acrylate) (PMA) as a reference dielectric and adjusting the soybean oil to methyl acrylate weight ratio in the polymerization process to form copolymers of PMA, totally three types of dielectrics were synthesized and transformed into a gel state to obtain the reduced CEFF. Gel dielectrics were named according to the soybean oil to methyl acrylate weight ratio. Such that, %0 ratio stands for NIGD0, %8 ratio stands for NIGD1 and %11 ratio stands for NIGD2 and OFETs fabricated with these NIGDs were named with regard to these names (NIGOFET0, NIGOFET1, and NIGOFET2). After the electrical characterization, it was seen that mobility enhanced as the CEFF decreased as predicted. It could be attributed to a formation of less self-localization of the charge carriers in the semiconductor-dielectric interface. Moreover, it was seen that NIGOFET1 had the lowest Subthreshold Swing (SS) and off-current (IOFF) consequently the highest on-to-off current ratio (ION/IOFF). It implied that it had better insulation property and semiconductor-dielectric interface compared to the other NIGOFETs. © 2019 Elsevier B.V.Firat University Scientific Research Projects Management Unit: 2015.05.03.381, 2017.07.02.621This work was supported by the Düzce University Scientific Research Projects unit under Grant [ 2017.07.02.621 ] and [ 2015.05.03.381 ]

Autoxidized Oleic Acid Bifunctional Macro Peroxide Initiators for Free Radical and Condensation Polymerization. Synthesis and Characterization of Multiblock Copolymers

Secilmis Canbay, Hale/0000-0002-3783-8064; Hazer, Baki/0000-0001-8770-805XWOS: 000491549500023TARAMASCOPUSIndex: SCI-E, WOS, ScopusTARAMAWOSAutoxidation of unsaturated fatty acids gives fatty acid macroperoxide initiators containing two functionalities which can lead to free radical and condensation polymerizations in a single pot. The oleic acid macroperoxide initiator obtained by ecofriendly autoxidation (Pole4m) was used in both the free radical polymerization of styrene and the condensation polymerization with amine-terminated polyethylene glycol (PEGNH2) to obtain triblock branched graft copolymers. The narrow molar masses of the poly oleic acid-g-styrene (PoleS) and poly oleic acid-g-styrene-g-PEG (PoSG) graft copolymers were successfully obtained. The inclusion of oleic acid decreased the glass transition temperature of the polystyrene segment because of the plasticizing effect of oleic acid. In addition, a mechanical property of the copolymer was improved when compared with the pure PS. Structural characterization, morphology of the fracture surface, micelle formation, thermal analysis and molar masses of the obtained products were also evaluated.Kapadokya University Research Fund [KUN.2018-BAGP-001]; Bulent Ecevit University Research FundBulent Ecevit University [BEU-2017-72118496-01]This work was supported by the Kapadokya University Research Fund (KUN.2018-BAGP-001) and Bulent Ecevit University Research Fund (#BEU-2017-72118496-01). The Authors thank to Koray Alper and Fatih Pekdemir for taking SEM and FTIR spectra, respectively. The Authors thank to Serdar Coban, Sidika Sarac Tabakli and Gulsen Darici (Cilas Kaucuk, Devrek, Zonguldak, Turkey) for taking stress-strain measurements