Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 16Citation - Scopus: 17Solid-State Encapsulation and Color Tuning in Films of Cesium Lead Halide Perovskite Nanocrystals for White Light Generation(Amer Chemical Soc, 2019-01-30) Torun, Ilker; Altintas, Yemliha; Yazici, Ahmet Faruk; Mutlugun, Evren; Onses, M. SerdarPerovskite 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.Article Citation - WoS: 9Citation - Scopus: 11Natural Wax-Stabilized Perovskite Nanocrystals as Pen-On Inks and Doughs(Amer Chemical Soc, 2022-04-19) Ocal, Sema Karabel; Kiremitler, N. Burak; Yazici, Ahmet Faruk; Celik, Nusret; Mutlugun, Evren; Onses, M. Serdar; Karabel Ocal, SemaPerovskite 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.Article Citation - WoS: 12Citation - Scopus: 14Nanowire-Shaped MoS2@MoO3 Nanocomposites as a Hole Injection Layer for Quantum Dot Light-Emitting Diodes(Amer Chemical Soc, 2022-08-01) Bastami, Nasim; Soheyli, Ehsan; Arslan, Aysenur; Sahraei, Reza; Yazici, Ahmet Faruk; Mutlugun, EvrenMolybdenum disulfides and molybdenum trioxides are structures that possess the potential to work as efficient charge transport layers in optoelectronic devices. In the present study, as opposed to the existing Mo-based nanostructures in flake, sheet, or spherical forms, an extremely simple and low-cost hydrothermal method is used to prepare nanowires (NWs) of MoS2@MoO3 (MSO) composites. The synthesis method includes several advantages including easy handling and processing of inexpensive precursors to reach stable MSO NWs without the need for an oxygen-free medium, which would facilitate the possibility of mass production of these nanostructures. The structural analysis confirmed the formation of MSO nanocomposites with different Mo valence states, as well as NWs of average length and diameter of 70 nm and 5 nm, respectively. In order to demonstrate their potential for optoelectronic applications, MSO NWs were blended into hole injection layers (HILs) in quantum dot-based light emitting diodes (QLEDs). Electroluminescence measurements show a substantial enhancement in both luminance (from 44,330 to 68,630 cd.m-2) and external quantum efficiency (from 1.6 to 2.3%), based on the increase in the ratio of MSO NWs from 3 to 10%. Interestingly, the addition of 10% volume of MSO NWs resulted in a remarkably smoother HIL with improved current efficiency and stability in green-emitting QLEDs. The simplicity and cost-effective features of the synthesis method along with outstanding favorable morphology demonstrated their ability to enhance the QLED performance and mark them as promising agents for optoelectronics.Article Citation - WoS: 2Citation - Scopus: 2Light-Controlled Electrostatic Self-Assembly of Quantum Dots(Amer Chemical Soc, 2025-04-11) Akrema; Phul, Ruby; Yazici, Ahmet Faruk; Senel, Zeynep; Erdem, TalhaElectrostatic self-assembly is one of the important self-assembly mechanisms that found use in optoelectronics. Although this method enables realizing unconventional architectures, producing complicated architectures in large areas requires local control over the self-assembly process. One of the ways to achieve this control is to provide enough kinetic energy to the self-assembling nanoparticles so that they can escape electrostatic attraction. We hypothesize that this energy can be delivered to the nanoparticles by treating them with light that can be absorbed by the particles. Here, we test this idea to tailor the electrostatic self-assembly of semiconductor quantum dots (QDs) using a laser. Employing fluorescence and atomic force microscopy, we demonstrate that the QDs are not attached to the substrate in regions where they are exposed to light while they are coated in the absence of optical excitation. We further conduct theoretical analysis to show that elevated temperatures indeed allow the QDs to escape the electrostatic attraction of the charged polymers on the surface. We also demonstrate that increasing the temperature during the coating process without irradiating the sample gives similar results as the case when the sample was irradiated. Finally, we fabricate an uncoated region on the self-assembled QD film with dimensions of similar to 200 mu m x 0.5 cm to demonstrate the feasibility of our approach to control the bottom-up self-assembly. We believe that our results may pave the way for a cost-effective and sustainable approach for the fabrication of nanoelectronic and optoelectronic devices.