Browsing by Author "Kiremitler, N. B."
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Item Embargo Fully transparent and superhydrophobic electrodes enabled by soft interfaces(Elsevier BV, 2022-12-16) Torun, İ.; Çelik, N.; Kiremitler, N. B.; Huang, X.; Önses, Mustafa SerdarThe simultaneous achievement of transparency, electrical conductivity and superhydrophobicity is a highly challenging and rewarding task for a range of technological applications. This manuscript reports a practical and fluorine-free approach for fully transparent and superhydrophobic coatings on a transparent electrode. The first step consists of the formation of a grafted film of poly(ethylene glycol) on an indium oxide coated glass substrate. The superhydrophobicity is then achieved by spray-coating a film of alkylsilane functionalized nanoparticles. The self-assembly of the hydrophobic nanoparticles on end-grafted poly(ethylene glycol) allows for controlled formation of roughness without sacrificing the transparency and electrical conductivity. The result is a multi-functional substrate with a static contact angle of 172°, sliding angle of 1°, 90.4% transparency at a wavelength of 550 nm, and a sheet resistance of 13.05 Ω/sq. The surface has high water impact-resistance and thermal stability provided by the soft-interface composed of end-grafted poly(ethylene glycol). The reported substrate exhibits outstanding figures of merit in terms of the water repellency, optoelectronic performance, and stability. Application in transparent heaters demonstrates the promise of the presented multi-functional coatings.Item Open Access Natural wax-stabilized perovskite nanocrystals as pen-on-paper inks and doughs(American Chemical Society, 2022-05-27) Karabel Ocal, S.; Kiremitler, N. B.; Yazici, A. F.; Çelik, N.; Önses, M. Serdar; Mutlugün, EvrenPerovskite nanocrystals (PNCs) are emerging luminescent materials for a wide range of technological applications. The broad adaptation of PNCs will be greatly improved by addressing their intrinsically low stability and developing processes for their assembly into 2D and 3D structures using facile approaches. Inspired by the mechanism of natural protection of leaves, this paper proposes natural carnauba wax (CW) as an encapsulation material for PNCs. The synthesis of PNCs is performed in the presence of CW, which is derived from the leaves of Copernicia prunifera palm. CW acts as a solvent and replaces the commonly used octadecene in the preparation of PNCs. The facile synthesis in CW results in PNCs with greatly improved thermal, water, and air stability. Furthermore, the thermal and mechanical properties make PNC-Wax a highly suitable solid ink for versatile processing of these materials into 2D and 3D architectures. PNC-Wax can be printed via a pen-on-paper approach by heating at modest temperatures. The rapid plasticization of PNC-Wax by mechanical agitation enables hand-shaping of the material in a manner similar to playdoughs, which would possibly enable the versatile use of this material for various applications. © 2022 American Chemical Society. All rights reserved.Item Open Access Organic light-emitting physically unclonable functions(Wiley-VCH Verlag GmbH & Co. KGaA, 2021-12-22) Kayacı, N.; Özdemir, R.; Kalay, M.; Kiremitler, N. B.; Usta, H.; Önses, Mustafa SerdarThe 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 (≈40 nm) at a modest temperature (170 °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.Item Open Access Rapid fabrication of high-performance transparent electrodes by electrospinning of reactive silver ink containing nanofibers(Elsevier, 2020) Kiremitler, N. B.; Esidir, A.; Gözütok, Z.; Özdemir, A. T.; Önses, M. SerdarAll-solution processable fabrication of high performance transparent conductive electrodes is vital for next-generation optoelectronics applications. In this study, rapid and versatile fabrication of high-performance transparent electrodes by synergetic integration of electrospun nanofibers and particle-free reactive silver inks is reported. Direct electrospinning of reactive silver ink containing polymer blend solution followed by a swift thermal annealing enables fabrication of transparent conductive electrodes (TCEs) with a sheet resistance of ∼1.9 Ω/sq with 90% transmission. The high-performance TCEs were fabricated within couple of minutes including the electrospinning and thermal annealing duration. The key aspects of our strategy are the use of a polymer blend consisting of poly(ethylene oxide) (PEO) and polyvinylpyrrolidone (PVP) and particle-free nature of reactive silver inks. Practical utility of the fabricated transparent electrodes in Joule heaters that work at temperatures as high as 300 °C is presented. The simple, versatile, inexpensive, and rapid fabrication of transparent conductive electrodes can enable broad range of applications.Item Open Access Tattoo-like multi-color physically unclonable functions(John Wiley and Sons Inc, 2023-12-07) Kiremitler, N. B.; Esidir, A.; Drake, G. A.; Yazıcı, A. F.; Şahin, F.; Torun, I.; Kalay, M.; Kelestemur, Y.; Demir, Hilmi Volkan; Shim, M.; Mutlugün, Evren; Önses, Mustafa SerdarAdvanced anti-counterfeiting and authentication approaches are in urgent need of the rapidly digitizing society. Physically unclonable functions (PUFs) attract significant attention as a new-generation security primitive. The challenge is design and generation of multi-color PUFs that can be universally applicable to objects of varied composition, geometry, and rigidity. Herein, tattoo-like multi-color fluorescent PUFs are proposed and demonstrated. Multi-channel optical responses are created by electrospraying of polymers that contain semiconductor nanocrystals with precisely defined photoluminescence. The universality of this approach enables the use of dot and dot-in-rod geometries with unique optical characteristics. The fabricated multi-color PUFs are then transferred to a target object by using a temporary tattoo approach. Digitized keys generated from the red, green and blue fluorescence channels facilitate large encoding capacity and rapid authentication. Feature matching algorithms complement the authentication by direct image comparison, effectively alleviating constraints associated with imaging conditions. The strategy that paves the way for the development of practical, cost-effective, and secure anticounterfeiting systems is presented.Item Open Access Writing chemical patterns using electrospun fibers as nanoscale inkpots for directed assembly of colloidal nanocrystals(Royal Society of Chemistry, 2020) Kiremitler, N. B.; Torun, İ.; Altıntaş, Y.; Patarroyo, J.; Demir, Hilmi Volkan; Puntes, V. F.; Mutlugün, Evren; Önses, Mustafa SerdarApplications that range from electronics to biotechnology will greatly benefit from low-cost, scalable and multiplex fabrication of spatially defined arrays of colloidal inorganic nanocrystals. In this work, we present a novel additive patterning approach based on the use of electrospun nanofibers (NFs) as inkpots for end-functional polymers. The localized grafting of end-functional polymers from spatially defined nanofibers results in covalently bound chemical patterns. The main factors that determine the width of the nanopatterns are the diameter of the NF and the extent of spreading during the thermal annealing process. Lowering the surface energy of the substrates via silanization and a proper choice of the grafting conditions enable the fabrication of nanoscale patterns over centimeter length scales. The fabricated patterns of end-grafted polymers serve as the templates for spatially defined assembly of colloidal metal and metal oxide nanocrystals of varying sizes (15 to 100 nm), shapes (spherical, cube, rod), and compositions (Au, Ag, Pt, TiO2), as well as semiconductor quantum dots, including the assembly of semiconductor nanoplatelets.