Browsing by Author "Onses, M. Serdar"

Now showing 1 - 10 of 10

Citation - WoS: 83
Citation - Scopus: 78
Organic Light-Emitting Physically Unclonable Functions
(Wiley-VCH Verlag GmbH, 2022) 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.
Citation - WoS: 5
Citation - Scopus: 3
Photoluminescent and Superhydrophobic Nanocomposites of Perovskite Nanocrystals
(Elsevier, 2024) Ocal, Sema Karabel; Celik, Nusret; Onses, M. Serdar; Mutlugun, Evren
Perovskite nanocrystals (PNCs) have found extensive utility across diverse technological applications in optoelectronics; nevertheless, their susceptibility to environmental instability poses a significant constraint on their practicality. Within this investigation, we present a novel and facile approach for the development of highly stable superhydrophobic PNCs. These engineered superhydrophobic perovskite nanocrystal composites, referred to as HSNPs@PNCs, demonstrate remarkable optoelectronic attributes, provided that their inherent instability can be effectively mitigated. HSNPs@PNCs manifest an impressive water contact angle of 172 degrees and an exceedingly low sliding angle of 1 degrees, thus showcasing their exceptional superhydrophobicity. Of particular note is the extraordinary stability exhibited by HSNPs@PNCs despite aqueous environments, thermal fluctuations, and UV exposure. Remarkably, even after a prolonged 30 -day immersion in water, this nanocomposite maintains an outstanding emission efficiency of 75 %. Furthermore, the method of application through a spray deposition technique circumvents sample size limitations, thereby amplifying their suitability for industrial applications. Moreover, this study extends the practicality of HSNPs@PNCs by enabling their homogeneous coating onto various surfaces such as glass, fabric, and aluminum, yielding luminescent superhydrophobic surfaces. This approach liberates the substrates from constraints, significantly broadening the potential spectrum of applications for these materials within diverse industrial and technological domains.
Citation - WoS: 16
Citation - Scopus: 17
Solid-State Encapsulation and Color Tuning in Films of Cesium Lead Halide Perovskite Nanocrystals for White Light Generation
(Amer Chemical Soc, 2019) Torun, Ilker; Altintas, Yemliha; Yazici, Ahmet Faruk; Mutlugun, Evren; Onses, M. Serdar
Perovskite nanocrystals (PNCs) are highly demanding nanomaterials for solid-state lighting applications. A challenge for their exploitation in practical applications is the insufficient ambient and water stability associated with their ionic nature. Here we report a novel route for solid-state encapsulation of films of perovskite nanocrystals (PNCs) through vapor-phase deposition of a thin and hydrophobic layer of fluoroalkyltrichlorosilanes (FAS). High quality nanoscale crystals of CsPbBr3 were synthesized with well established colloidal methods and coated on solid substrates. The films of PNCs were then subjected to vapor of FAS for short durations of time (<60 s) in ambient atmosphere, resulting in deposition of a thin (<20 nm) hydrophobic layer. Besides providing a barrier for water and humidity, the vapor-phase deposition of FAS was accompanied by the blue shift of the emission wavelength of the PNCs. The color shift results from the partial exchange of Br with Cl anions, which emerge during the self-hydrolysis of the silane molecules. Throughout this process, we demonstrate the enhanced water stability of the films of PNCs and fine tunability of the wavelength in films from 516 nm to 488 nm. The fabrication of a white-light-emitting diode and tunability of the color coordinates with the duration of the FAS deposition were demonstrated. The rapid, scalable, and inexpensive solid-state encapsulation approach shows great promise for films of halide perovskites.
Citation - WoS: 15
Citation - Scopus: 18
FRET Enabled Light Harvesting within Quantum Dot Loaded Nanofibers
(IOP Publishing Ltd, 2018) Altintas, Yemliha; Kiremitler, Nuri Burak; Genc, Sinan; Onses, M. Serdar; Mutlugun, Evren
The spatial control of the nano-emitters in novel light harvesting platforms offers great potential for the manipulation of the excitonic interaction amongst the donor-acceptor pairs of energy transferring agents. In this work, we report colloidal quantum dot loaded electrospun nanofibers as a light harvesting platform to study the excitonic interaction among them. The donor emission lifetime modified from 12.46 ns to 7.45 ns with the change in the ratio of green and red quantum dots in the nanofiber, as a result of confining acceptor quantum dots in close proximity. The spectrally narrow emitter luminescent nanofiber platforms have further been investigated for their potential of white light generation. The hybrid platform of blue LED integrated electrospun nanofibers has been shown to demonstrate a correlated color temperature of 3632.5 K, luminous efficacy of optical radiation value of 307.7 lm/W-opt along with color rendering index value of 60.
Citation - WoS: 31
Citation - Scopus: 31
Flexible Electrodes Composed of Flower-Like MoS2 and MXene for Supercapacitor Applications
(Pergamon-Elsevier Science Ltd, 2024) Hayat, Hilal Pecenek; Dokan, Fatma Kilic; Onses, M. Serdar; Yilmaz, Erkan; Duran, Ali; Sahmetlioglu, Ertugrul
Flexible supercapacitors with high charge storage ability are needed for emerging applications in wearable electronics. Here, we introduce a novel flexible supercapacitor electrode by incorporating flower-like MoS2 into MXene via a hydrothermal technique. We mostly focused on the structural design for electrode configuration to enhance the charge storage mechanism. Three different electrodes composed of MoS2, MXene, and MoS2@MXene were fabricated via a versatile drop-casting and drying method. There are unique advantages of incorporating MoS2 with MXene such as the fast electron transfer, hydrophilicity of the interface, and structural stability. The MoS2@MXene // MXene flexible asymmetric supercapacitor device offered a high energy density of 1.21 W h /kg and a power density of 54.45 W /kg. Moreover, the asymmetric device exhibits nearly identical electrochemical behavior following 100 bending cycles at different angles. The high electrochemical activity of MoS2 and MXene and good interaction are ascribed to the superior electrochemical performance of the composite material. Furthermore, this research could guide the development of flexible, high-performance, and low-cost electrodes which will be useful in wearable electronics.
Citation - WoS: 9
Citation - Scopus: 10
Natural Wax-Stabilized Perovskite Nanocrystals as Pen-On Inks and Doughs
(Amer Chemical Soc, 2022) Ocal, Sema Karabel; Kiremitler, N. Burak; Yazici, Ahmet Faruk; Celik, Nusret; Mutlugun, Evren; Onses, M. Serdar
Perovskite 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.
Citation - WoS: 8
Citation - Scopus: 8
Writing Chemical Patterns Using Electrospun Fibers as Nanoscale Inkpots for Directed Assembly of Colloidal Nanocrystals
(Royal Soc Chemistry, 2020) Kiremitler, N. Burak; Torun, Ilker; Altintas, Yemliha; Patarroyo, Javier; Demir, Hilmi Volkan; Puntes, Victor F.; Onses, M. Serdar
Applications 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.
Enhanced Photoluminescence via Plasmonic Gold Nanoparticles and Improved Stability of Perovskite Nanocrystals in Macroporous (Polydimethylsiloxane) PDMS Matrices
(Springer, 2025) Ocal, Sema Karabel; Tiras, Kevser Sahin; Onses, M. Serdar; Mutlugun, Evren
In this work, we report a simple and cost-effective method for improving both the environmental stability and photoluminescence quantum efficiency (PLQY) of perovskite nanocrystals (PNCs). Through their embedding in a specially designed macroporous polydimethylsiloxane (MPDMS) matrix and incorporation of plasmonic gold nanoparticles (Au NPs), remarkable improvements are achieved. The resulting MPDMS@PNC composites are seen to retain near-unity quantum efficiency even after 24-h immersion in water and are observed to retain over 85% of the original efficiency even at 75 degrees C, displaying excellent thermal stability. More interestingly, by incorporating Au NPs and subjecting the material to mechanical pressure, the lifetime of the PNCs gets further increased. This is due to the more intimate spatial arrangement of Au NPs in the porous matrix, enhancing localized surface plasmon resonance (LSPR) coupling and thereby enhancing the photoluminescence (PL) of the PNCs. In general, this approach offers a scalable and robust route to designing stable, high-performance perovskite-based materials for next-generation optoelectronic applications.
Citation - WoS: 19
Citation - Scopus: 18
Tattoo-Like Multi-Color Physically Unclonable Functions
(Wiley-VCH Verlag GmbH, 2024) Kiremitler, N. Burak; Esidir, Abidin; Drake, Gryphon A.; Yazici, Ahmet Faruk; Sahin, Furkan; Torun, Ilker; Onses, M. Serdar
Advanced 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. Tattoo-like multi-color encoding layers based on random processing of semiconductor nanocrystals of varied composition and geometry are reported. Additive deposition via chaotic electrospraying enables randomness and multiplexing, whereas the tattoo approach provides substrate independence.image
Citation - WoS: 50
Citation - Scopus: 50
Multiplexed Patterning of Cesium Lead Halide Perovskite Nanocrystals by Additive Jet Printing for Efficient White Light Generation
(Elsevier Science SA, 2020) Altintas, Yemliha; Torun, Ilker; Yazici, Ahmet Faruk; Beskazak, Emre; Erdem, Talha; Onses, M. Serdar; Mutlugun, Evren
Inorganic perovskite nanocrystals (PNCs) offer the ability to precisely but also flexibly control the peak emission wavelength while also possessing narrow-band emission spectra and high quantum yields. Owing to these features, PNCs have been already employed as color converters on LEDs. Nevertheless, the anion exchange reactions that prevent the blending of perovskites of different colors remain as an important bottleneck. As a remedy to this issue, here we employ additive jet printing to form separated stripes of these nanocrystals. Within this framework, we first present the synthesis of CsPbBr3 and CsPbBrxI3-x nanocrystals spanning the whole visible regime and optimize the cleaning procedure to obtain PNCs possessing photoluminescence quantum yields as high as 91% and emission linewidths as narrow as 15 nm, making them suitable for high quality white light generation. Next, we employ electrohydrodynamic jet printing to form closely spaced stripes of PNCs of various colors and integrated these films with a blue LED to create a white LED. Our proof-of-concept LED achieves high photometric performance as it possesses a color rendering index of 91.3, luminous efficacy of optical radiation > 300 lm/W-opt, and correlated color temperature of ca. 7000 K. We believe that additive jet printing technique will pave the way for a ubiquitous use of these PNCs in light-emitting devices in the near future.