WoS İndeksli Yayınlar Koleksiyonu

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

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Author: search.filters.author.Usta, HakanPublisher: search.filters.publisher.Wiley-VCH Verlag GmbH

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Now showing 1 - 6 of 6
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Stochastic Orientational Encoding via Hydrogen Bonding Driven Assembly of Woven-Like Molecular Physically Unclonable Functions
    (Wiley-VCH Verlag GmbH, 2025-07-02) Kayaci, Nilgun; Kiremitler, Nuri Burak; Deneme, Ibrahim; Kalay, Mustafa; Ozbasaran, Aleyna; Zorlu, Yunus; Usta, Hakan
    The prevention of counterfeiting and the assurance of object authenticity require stochastic encoding schemes based on physically unclonable functions (PUFs). There is an urgent need for exceptionally large encoding capacities and multi-level responses within a molecularly defined, single-material system. Herein, a novel stochastic orientational encoding approach is demonstrated using a facile ambient-atmosphere solution processing of a molecular thin film based on the rod-shaped oligo(p-phenyleneethynylene) (OPE) pi-architecture. The nanoscopic film, derived from the small molecule 2EHO-CF3PyPE with donor, acceptor, and pi-spacer building units, is designed for energetically favorable uniaxial molecular assembly and crystal growth via directional multiple hydrogen-bonding motifs at the molecular termini and short C & horbar;H<middle dot><middle dot><middle dot>pi contacts at the center. A facile solvent vapor annealing induces concurrent dewetting and microscopic 1D random crystallization, yielding a woven-textured random features. Using convolutional neural networks, the rich variations in microcrystal domain properties and stochastic encoding of 1D crystal orientations generate artificial coloration, achieving an encoding capacity reaching (6.5 x 10(4))(2752 x 2208). The results demonstrate an effective strategy for achieving ultrahigh encoding capacities in a thin film composed of a single-material. This approach enables low-cost, solution-processed fabrication for mass production and broad adoption, while opening new opportunities to explore molecular-PUFs through structural design and engineering noncovalent interactions.
  • Article
    Citation - WoS: 36
    Citation - Scopus: 36
    Selective Remanent Ambipolar Charge Transport in Polymeric Field-Effect Transistors for High-Performance Logic Circuits Fabricated in Ambient
    (Wiley-VCH Verlag GmbH, 2014-10-06) Fabiano, Simone; Usta, Hakan; Forchheimer, Robert; Crispin, Xavier; Facchetti, Antonio; Berggren, Magnus
  • Article
    Citation - WoS: 88
    Citation - Scopus: 83
    Organic Light-Emitting Physically Unclonable Functions
    (Wiley-VCH Verlag GmbH, 2021-12-22) Kayaci, Nilgun; Ozdemir, Resul; Kalay, Mustafa; Kiremitler, N. Burak; Usta, Hakan; Onses, M. Serdar
    The development of novel physically unclonable functions (PUFs) is of growing interest and fluorescent organic semiconductors (f-OSCs) offer unique advantages of structural versatility, solution-processability, ease of processing, and great tuning ability of their physicochemical/optoelectronic/spectroscopic properties. The design and ambient atmosphere facile fabrication of a unique organic light-emitting physically unclonable function (OLE-PUF) based on a green-emissive fluorescent oligo(p-phenyleneethynylene) molecule is reported. The OLE-PUFs have been prepared by one-step, brief (5 min) thermal annealing of spin-coated nanoscopic films (approximate to 40 nm) at a modest temperature (170 degrees C), which results in efficient surface dewetting to form randomly positioned/sized hemispherical features with bright fluorescence. The random positioning of molecular domains generated the unclonable surface with excellent uniformity (0.50), uniqueness (0.49), and randomness (p > 0.01); whereas the distinctive photophysical and structural properties of the molecule created the additional security layers (fluorescence profile, excited-state decay dynamics, Raman mapping/spectrum, and infrared spectrum) for multiplex encoding. The OLE-PUFs on substrates of varying chemical structures, surface energies and flexibility, and direct deposition on goods via drop-casting are demonstrated. The OLE-PUFs immersed in water, exposed to mechanical abrasion, and read-out repeatedly via fluorescence imaging showed great stability. These findings clearly demonstrate that rationally engineered solution-processable f-OSCs have a great potential to become a key player in the development of new-generation PUFs.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 21
    Enhancement of Anhydrous Proton Conductivity of Poly(Vinylphosphonic Acid)-Poly(2,5 Membranes Via in Situ Polymerization
    (Wiley-VCH Verlag GmbH, 2014-10-16) Sen, Unal; Usta, Hakan; Acar, Oktay; Citir, Murat; Canlier, Ali; Bozkurt, Ayhan; Ata, Ali
    Polymer electrolyte membranes (PEMs) are synthesized via in situ polymerization of vinylphosphonic acid (VPA) within a poly(2,5-benzimidazole) (ABPBI) matrix. The characterization of the membranes is carried out by using Fourier transform infrared (FTIR) spectroscopy for the interpolymer interactions, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for the thermal properties, and scanning electron microscopy (SEM) for the morphological properties. The physicochemical characterizations suggest the complexation between ABPBI and PVPA and the formation of homogeneous polymer blends. Proton conductivities in the anhydrous state (150 degrees C) measured by using impedance spectroscopy are considerable, at up to 0.001 and 0.002 S cm(-1) for (1: 1) and (1: 2) molar ratios, respectively. These conductivities indicate signifi cant improvements (> 1000x) over the physically blended samples. The results shown here demonstrate the great potential of in situ preparation for the realization of new PEM materials in future high-temperature and non-humidified polymer electrolyte membrane fuel cell (PEMFC) applications.
  • Article
    Citation - WoS: 110
    Citation - Scopus: 116
    Bodipy-Based Semiconducting Materials for Organic Bulk Heterojunction Photovoltaics and Thin-Film Transistors
    (Wiley-VCH Verlag GmbH, 2018-12-13) Ho, Dongil; Ozdemir, Resul; Kim, Hyungsug; Earmme, Taeshik; Usta, Hakan; Kim, Choongik
    The rapid emergence of organic (opto)electronics as a promising alternative to conventional (opto)electronics has been achieved through the design and development of novel pi-conjugated systems. Among various semiconducting structural platforms, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) pi-systems have recently attracted attention for use in organic thin-films transistors (OTFTs) and organic photovoltaics (OPVs). This Review article provides an overview of the developments in the past 10 years on the structural design and synthesis of BODIPY-based organic semiconductors and their application in OTFT/OPV devices. The findings summarized and discussed here include the most recent breakthroughs in BODIPYs with record-high charge carrier mobilities and power conversion efficiencies (PCEs). The most up-to-date design rationales and discussions providing a strong understanding of structure-property-function relationships in BODIPY-based semiconductors are presented. Thus, this review is expected to inspire new research for future materials developments/applications in this family of molecules.
  • Article
    Citation - WoS: 29
    Citation - Scopus: 30
    A Solution-Processable Liquid-Crystalline Semiconductor for Low-Temperature Air-Stable N-Channel Field-Effect Transistors
    (Wiley-VCH Verlag GmbH, 2017-02-22) Ozdemir, Resul; Choi, Donghee; Ozdemir, Mehmet; Kim, Hyekyoung; Kostakoglu, Sinem Tuncel; Erkartal, Mustafa; Usta, Hakan
    A new solution-processable and air-stable liquid-crystalline nchannel organic semiconductor (2,2'-(2,8-bis(5-(2-octyldodecyl) thiophen-2-yl) indeno[1,2-b] fluorene-6,12-diylidene) dimalononitrile, alpha,omega-2OD-TIFDMT) with donor-acceptor-donor (D-AD) pi conjugation has been designed, synthesized, and fully characterized. The new semiconductor exhibits a low LUMO energy (-4.19 eV) and a narrow optical bandgap (1.35 eV). The typical pseudo-focal-conic fan-shaped texture of a hexagonal columnar liquid-crystalline (LC) phase was observed over a wide temperature range. The spin-coated semiconductor thin films show the formation of large (approximate to 0.5-1 mu m) and highly crystalline platelike grains with edge-on molecular orientations. Low-temperature-annealed (50 degrees C) top-contact/bottom-gate OFETs have provided good electron obility values as high as 0.11 cm(2) (Vs)(-1) and high I-on/I-off ratios of 10(7) to 10(8) with excellent ambient stability. This indicates an enhancement of two orders of magnitude (100 V) when compared with the b-substituted parent semiconductor, beta-DD-TIFDMT (2,2'-(2,8-bis(3-dodecylthiophen- 2-yl) indeno[1,2-b] fluorene-6,12-diylidene) dimalononitrile). The current rational alkyl-chain engineering route offers great advantages for D-A-D pi-core coplanarity in addition to maintaining good solubility in organic solvents, and leads to favorable optoelectronic/physicochemical characteristics. These remarkable findings demonstrate that alpha,omega-2OD-TIFDMT is a promising semiconductor material for the development of n-channel OFETs on flexible plastic substrates and LC-state annealing of the columnar liquid crystals can lower the electron mobility for transistor-type charge transport.