WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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Author: search.filters.author.Zorlu, YunusPublisher: search.filters.publisher.Royal Soc Chemistry

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 25
    Citation - Scopus: 25
    Triisopropylsilylethynyl-Substituted Indenofluorenes: Carbonyl Versus Dicyanovinylene Functionalization in One-Dimensional Molecular Crystals and Solution-Processed N-Channel Ofets
    (Royal Soc Chemistry, 2018) Ozdemir, Resul; Park, Sangyun; Deneme, Ibrahim; Park, Yonghan; Zorlu, Yunus; Alidagi, Husniye Ardic; Usta, Hakan
    The design and synthesis of novel electron-deficient and solution-processable polycyclic aromatic hydrocarbons offers great opportunities for the development of low-cost and large-area (opto)electronics. Although (trialkylsilyl)ethynyl (R3Si-C?C-) has emerged as a very popular unit to solubilize organic semiconductors, it has been applied only to a limited class of materials that are mostly substituted on short molecular axes. Herein, two novel solution-processable indenofluorene-based semiconductors, TIPS-IFDK and TIPS-IFDM, bearing (triisopropylsilyl)ethynyl end units at 2,8-positions (long molecular axis substitution) were synthesized, and their single-crystal structures, optoelectronic properties, solution-sheared thin-film morphologies/microstructures, and n-channel field-effect responses were studied. In accordance with the DFT calculations, the HOMO/LUMO energies of the new compounds are found to be -5.77/-3.65 eV and -5.84/-4.18 eV for TIPS-IFDK and TIPS-IFDM, respectively, reflecting the high electron deficiency of the new -backbones. Both semiconductors exhibit slightly S-shaped molecular frameworks with highly coplanar IFDK/IFDM -cores, and they form slipped -stacked one-dimensional (1-D) columnar motifs in the solid state. However, substantial differences in the degree of - interactions and stacking distances (4.04 angstrom vs. 3.47 angstrom) were observed between TIPS-IFDK and TIPS-IFDM as a result of carbonyl vs. dicyanovinylene functionalization, which results in a three orders of magnitude variation in the charge carrier mobility of the corresponding thin films. Top-contact/bottom-gate OFETs fabricated via solution-shearing TIPS-IFDM yielded one of the best performances in the (trialkylsilyl)ethynyl literature ((e) = 0.02 cm(2) V-1 s(-1), I-on/I-off = 10(7)-10(8), and V-T approximate to 2 V under ambient atmosphere) for a 1-D polycrystalline semiconductor microstructure. To the best of our knowledge, the molecules presented here are the first examples of n-type semiconductors substituted with (trialkylsilyl)ethynyl groups on their long molecular axes.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 15
    Engineering Functionalized Low LUMO [1]Benzothieno[3,2-B][1]Benzothiophenes (BTBTs): Unusual Molecular and Charge Transport Properties
    (Royal Soc Chemistry, 2020) Ozdemir, Resul; Ahn, Kyunghan; Deneme, Ibrahim; Zorlu, Yunus; Kim, Dojun; Kim, Myung-Gil; Usta, Hakan
    Diacene-fused thienothiophenes (DAcTTs) have provided an excellent pi-framework for the development of high mobility p-type molecular semiconductors in the past decade. However, n-type DAcTTs are rare and their electron transport characteristics remain largely unexplored. Herein, a series of functionalized low LUMO (lowest unoccupied molecular orbital) [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based small molecules, D(C7CO)-BTBT, C7CO-BTBT-CC(CN)(2)C-7, and D(C7CC(CN)(2))-BTBT, have been developed. Detailed structural, physicochemical, optoelectronic, and single-crystal characterization were performed. The new molecules exhibit large optical band gaps (similar to 2.8-3.1 eV) and highly stabilized (-Delta E-LUMO = 1.2-1.4 eV)/pi-delocalized LUMOs as compared to p-type DAcTTs. Symmetric functionalization is found to be important to enable strong intermolecular interactions in the solid-state. All molecules exhibit alternately stacked layers of "F-BTBT-F" and "S" (F: functional group/S: substituent) with strong herringbone-like interactions (2.8-3.6 angstrom distances) between pi-cores. While carbonyls, regardless of the substituent, adopt nearly coplanar pi-backbones with BTBT, dicyanovinylenes are found to be twisted (47.5 degrees). The conformational difference at the molecular level has unusual effects on the pi-electron deficiencies, frontier molecular orbital energetics, thermal/photophysical properties, and pi-electronic structures. Dicyanovinylenes at the 2,7 positions, despite twisted conformations, are shown for the first time to yield good electron transport in DAcTTs. The D(C7CC(CN)(2))-BTBT thin film exhibits large 2D plate-like crystalline grains (similar to 1-2 mu m sizes) of terraced islands and becomes a rare example of an n-type DAcTT in organic field-effect transistors (OFETs). Although a stabilized/pi-delocalized LUMO, largely governed by functional groups and intramolecular twists, is essential for electron transport, our findings suggest that it should be combined with proper substituents to yield a favorable three-dimensional BTBT/functional group pi-electronic structure and a low intramolecular reorganization energy. Combined with our first n-type DAcTT semiconductor D(PhFCO)-BTBT, a molecular library with systematically varied chemical structures has been studied herein for the first time for low LUMO DAcTTs. The molecular engineering perspectives presented in this study may give unique insights into the design of novel electron transporting thienoacenes for unconventional optoelectronics.
  • Article
    Citation - WoS: 40
    Citation - Scopus: 40
    Design, Synthesis, and Characterization of Α,ω-Disubstituted Indeno[1,2-B]Fluorene Molecular Semiconductors. Enhancement of Ambipolar Charge Transport Through Synthetic Tailoring of Alkyl Substituents
    (Royal Soc Chemistry, 2016) Ozdemir, Mehmet; Choi, Donghee; Kwon, Guhyun; Zorlu, Yunus; Kim, Hyekyoung; Kim, Myung-Gil; Usta, Hakan
    A series of indeno[1,2-b]fluorene-6,12-dione-thiophene derivatives with hydrocarbon substituents at alpha,omega-positions as side groups have been designed and synthesized. The new compounds were fully characterized by H-1/C-13 NMR, mass spectrometry, cyclic voltammetry, UV-vis absorption spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and melting point measurements. The solid state structure of the indeno[1,2-b]fluorene-6,12-dione acceptor core has been identified based on single-crystal X-ray diffraction (XRD). The structural and electronic properties were also studied using density functional theory calculations, which were found to be in excellent agreement with the experimental findings and provided further insight. The detailed effects of alkyl chain size and orientation on the optoelectronic properties, intermolecular cohesive forces, thin-film microstructures, and charge transport performance of the new semiconductors were investigated. Two of the new solution-processable semiconductors, 2EH-TIFDKT and 2OD-TIFDKT, were deposited as thin-films via solution-shearing, drop-casting, and droplet-pinned crystallization methods, and their morphologies and microstructures were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The solution-processed thin-film transistors based on 2EH-TIFDKT and 2OD-TIFDKT showed ambipolar device operations with electron and hole mobilities as high as 0.12 cm(2) V-1 s(-1) and 0.02 cm(2) V-1 s(-1), respectively, with Ion/Ioff ratios of 105 to 106. Here, we demonstrate that rational repositioning of the b-substituents to molecular termini greatly benefits the p-core planarity while maintaining a good solubility, and results in favorable structural and optoelectronic characteristics for more efficient charge-transport in the solid-state. The ambipolar charge carrier mobilities were increased by two-three orders of magnitude in the new indeno[1,2-b]fluorene-6,12-dione-thiophene core on account of the rational side-chain engineering.
  • Article
    Citation - WoS: 39
    Citation - Scopus: 40
    A New Rod-Shaped Bodipy-Acetylene Molecule for Solution-Processed Semiconducting Microribbons in N-Channel Organic Field-Effect Transistors
    (Royal Soc Chemistry, 2017) Ozdemir, Mehmet; Choi, Donghee; Zorlu, Yunus; Cosut, Bunyemin; Kim, Hyungsug; Kim, Choongik; Usta, Hakan
    BODIPY-based pi-conjugated small molecules have been extensively studied in various fields of sensing and biochemical labelling; however, their use in organic optoelectronic applications is very limited. A new solution-processable acceptor-donor-acceptor (A-D-A) type small molecule, BDY-PhAc-BDY, consisting of BODIPY pi-acceptors and a rod-shaped 1,4-bis-(thienylethynyl) 2,5-dialkoxybenzene pi-donor, has been synthesized and fully characterized as a novel n-channel semiconductor in bottom-gate/top-contact organic field-effect transistors (OFETs). The new semiconductor exhibits an electrochemical band gap of 2.12 eV with highly stabilized HOMO/LUMO energy levels of -5.68 eV/-3.56 eV. Single-crystal X-ray diffraction (XRD) analysis of BDY-PhAc-BDY reveals a relatively low "BODIPY-meso-thiophene" dihedral angle (theta = 44.94 degrees), antiparallel pi-stacked BODIPY dimers with an interplanar distance of 3.93 angstrom, and strong "C-H center dot center dot center dot pi (2.85 angstrom)" interactions. The OFET devices fabricated by solution processing show the formation of highly-crystalline, one-dimensional (1-D) microribbons, which results in clear n-channel semiconductivity with an electron mobility of 0.004 cm(2) V-1 s(-1) and an on/off current ratio of 10(5)-10(6). To date, this is the highest reported for BODIPY-based small molecular semiconductors with alkyne linkages. Our results clearly demonstrate that BODIPY is an effective pi-acceptor unit for the design of solution-processable, electron-transporting organic semiconductors and easily fabricable 1-D semiconductor micro-/nano-structures for fundamental/applied research in organic optoelectronics.