Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Enhanced Photoluminescence and Stability of CsPbBr3 Perovskite Nanocrystals Through AuCl Doping(Springer, 2026-02) Khorasani, Azam; Mutlugun, EvrenThis study delves into the transformative effects of inorganic gold chloride (AuCl) doping on all-inorganic cesium lead bromide (CsPbBr3) colloidal perovskite quantum dots (PeQDs). Using a precise hot injection synthesis method, AuCl was introduced at concentrations ranging from 0 to 10%, enabling a comprehensive analysis of its impact on the structural, morphological, and optical characteristics of CsPbBr3 PeQDs. We systematically investigated how varying AuCl levels influence photoluminescence (PL), PL quantum yield (PLQY), and the stability of these quantum dots. Advanced characterization techniques, including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), UV-Vis absorption, steady-state PL, absolute PL measurement, and time-resolved PL (TRPL), provided a detailed insight into these changes. Our findings indicate that AuCl doping is successfully integrated into CsPbBr3 PeQDs, with 5% identified as the optimal concentration. At this level, the quantum dots show enhanced PLQY, superior crystallinity, and increased stability at 50 degrees C and in ethanol solvent compared to undoped samples. While higher doping levels reduce QY and PL slightly, they still outperform the undoped CsPbBr3 PeQDs. These results demonstrate that AuCl doping can fine-tune the structural and optical properties of CsPbBr3 PeQDs, marking a significant step forward in developing tailored materials for advanced optoelectronic applications.Article Performance Boost in QLEDs Using Octanethiol-Capped Core/Shell Quantum Dots(IOP Publishing Ltd, 2026-01-07) Yazici, Ahmet F.; Yuruc, Adnan M.; Kelestemur, Yusuf; Serin, Ramis Berkay; Kacar, Rifat; Ulku, Alper; Mutlugun, EvrenQuantum dots attract significant attention as one of the most promising colloidal nanocrystals with unique optical properties and potential applications for the next generation of display technology. In this paper, we evaluate the performance of CdZnSeS-based alloyed-shell quantum dots (QDs) for electroluminescence devices upon additional shell growth and ligand exchange. This includes core/shell (C/S) and core/shell/shell (C/S/S) QDs, whose latter includes an additional ZnS shell and octanethiol (OT) ligands. We present detailed characterizations of QDs using transmission electron microscopy, XRD, and various spectroscopic techniques and demonstrate their QD light emitting (QLEDs). We find the photoluminescence quantum yield of C/S/S QDs increased from 68.8% to 88.7% compared to C/S QDs whereas the emission linewidth narrows from 22.2 nm to 20.8 nm. QLEDs fabricated with C/S/S QDs exhibit a higher peak external quantum efficiency (EQE) of 4.1% and maximum luminance of 85 000 cd m-2, compared to 2.3% EQE and 67 000 cd m-2 for C/S QLEDs. In this respect, the OT-assisted shell growth significantly improves the optical property of QDs and performance of QLEDs, likely attributed to the enhanced charge balance and increased radiative recombination rate.Article Citation - WoS: 2Citation - Scopus: 1Fully Inorganic Colloidal CsPbBr3 Perovskite Nanocrystals with Zn-Doping and Metal Oxide Encapsulation for Luminescent Display Panels(Amer Chemical Soc, 2025-11-07) Khorasani, Azam; Soheyli, Ehsan; Mutlugun, EvrenPerovskite nanocrystals (PeNCs) are emerging as exceptional materials due to their high photoluminescence quantum yield, tunable bandgap, and excellent charge carrier mobility, enabling a wide range of colors and promising applications in optoelectronics and photovoltaics. Despite their advantages, PeNCs face stability challenges caused by environmental factors. In the presented study, a facile and versatile colloidal hot-injection method was used to apply the beneficial aspects of Zn-doping in cesium lead bromide (CsPbBr3) PeNCs. The uniform platelet-shaped Zn-doped CsPbBr3 PeNCs were prepared by doping with a 0.1 molar ratio of zinc-oleate solution in the perovskite precursors during synthesis. Then, zinc-oxide (ZnO) and nickel-oxide (NiO) coating layers were utilized separately to effectively reduce surface defects, encapsulate PeNCs, and improve their stability issues. To fabricate the coated PeNCs with metal oxides, zinc acetate and nickel(II) acetate tetrahydrate solutions were prepared individually and added to the crude perovskite solutions. The quantum yield of Zn-doped CsPbBr3 (CsPb1-xZnxBr3) PeNCs coated with ZnO increased from 50% for bare CsPbBr3 to over 84%, while NiO-coated PeNCs exhibited a higher yield of 90% both of which remarkably enhanced the emission stability. Moreover, NiO coatings represented a proper protection against surface imperfections and improved resistance to external stimuli. The combination of facile/effective preparation method, excellent emission efficiency, and reliable emission stability nominates the prepared colloidal composite for display pixels, detectors, and lasers.Article Enhanced Photoluminescence via Plasmonic Gold Nanoparticles and Improved Stability of Perovskite Nanocrystals in Macroporous (Polydimethylsiloxane) PDMS Matrices(Springer, 2025-10-09) Ocal, Sema Karabel; Tiras, Kevser Sahin; Onses, M. Serdar; Mutlugun, EvrenIn 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.Article Zinc Chalcogenide Based Shell Layers for Colloidal Quantum Wells(Wiley, 2025-04-27) Aldemir, Cagatay Han; Yazici, Ahmet Faruk; Ergezer, Nehir; Korkmaz, Taha Can; Mutlugun, Evren; Kelestemur, YusufColloidal quantum wells, also known as colloidal nanoplatelets (NPLs), have emerged as a promising class of materials for light-emitting devices (LEDs). However, the most widely studied core/shell NPLs, which rely on cadmium-based shell layers, face challenges due to toxicity concerns and improper charge confinement. To address these limitations, a new synthetic approach is presented that enables the controlled growth of zinc chalcogenide-based shell layers on NPLs. The synthesized CdSe/ZnSe core/shell NPLs exhibit emission between 615 and 630 nm, with a moderate photoluminescence quantum yield (PL-QY) of 40-50%. It is also demonstrated that the lateral dimensions of the CdSe core NPLs significantly affect the optical properties of the core/shell heterostructures, with smaller lateral dimensions resulting in narrower emission linewidths as low as 20 nm. Further passivation of these core/shell NPLs with an additional ZnS shell layer significantly increases the PL-QY up to 80-90%. Finally, the device performance of these two core/shell NPLs is investigated by fabricating solution-processed LEDs. With LEDs incorporating CdSe/ZnSe/ZnS core/multi-shell NPLs as the active light-emitting layer, an external quantum efficiency (EQE) of 3.82% and a maximum brightness of 6477 cd m-2 is obtained. These findings underscore the significant potential of zinc chalcogenide-based shell layers in advancing colloidal NPLs toward high-performance light-emitting devices.Article Citation - WoS: 13Citation - Scopus: 13Tuning the Shades of Red Emission in InP/ZnSe Nanocrystals With Narrow Full Width for Fabrication of Light-Emitting Diodes(Amer Chemical Soc, 2023-10-13) Soheyli, Ehsan; Bicer, Aysenur; Ozel, Sultan Suleyman; Tiras, Kevser Sahin; Mutlugun, Evren; Sahin Tiras, KevserWhile Cd-based luminescent nanocrystals (NCs) are the most mature NCs for fabricating efficient red light-emitting diodes (LEDs), their toxicity related limitation is inevitable, making it necessary to find a promising alternative. From this point of view, multishell-coated, red-emissive InP-based NCs are excellent luminescent nanomaterials for use as an emissive layer in electroluminescent (EL) devices. However, due to the presence of oxidation states, they suffer from a wide emission spectrum, which limits their performance. This study uses tris-(dimethyl-amino)-phosphine (3DMA-P) as a low-cost aminophosphine precursor and a double HF treatment to suggest an upscaled, cost-effective, and one-pot hot-injection synthesis of purely red-emissive InP-based NCs. The InP core structures were coated with thick layers of ZnSe and ZnS shells to prevent charge delocalization and to create a narrow size distribution. The purified NCs showed an intense emission signal as narrow as 43 nm across the entire red wavelength range (626-670 nm) with an emission quantum efficiency of 74% at 632 nm. The purified samples also showed an emission quantum efficiency of 60% for far-red wavelengths of 670 nm with a narrow full width of 50 nm. The samples showed a relatively long average emission lifetime of 50-70 ns with a biexponential decay profile. To demonstrate the practical ability of the prepared NCs in optoelectronics, we fabricated a red-emissive InP-based LEDs. The best-performing device showed an external quantum efficiency (EQE) of 1.16%, a luminance of 1039 cd m(-2), and a current efficiency of 0.88 cd A(-1).Article Citation - WoS: 14Citation - Scopus: 13Spectrally Tunable White Light-Emitting Diodes Based on Carbon Quantum Dot-Doped Poly(N-Vinylcarbazole) Composites(Amer Chemical Soc, 2024-01-26) Sahin Tiras, Kevser; Bicer, Aysenur; Soheyli, Ehsan; Mutlugun, EvrenElectroluminescent white light-emitting diodes (WLEDs) are always of great interest for emerging display applications. Carbon-based quantum dots (CQDs) are the newest emerging nanoscale materials that can be employed for this purpose, owing to their broad and bright light emission properties. In the present work, highly luminescent CQDs with an emission quantum yield of 60% were prepared via a colloidal solvothermal method and subsequent silica gel column chromatography. The photoluminescence (PL) peak was located at 550 nm possessing yellow emission, with a full width at half-maximum of 98 nm and a relatively long lifetime of 10.23 ns through a single-exponential recombination pathway. CQDs were employed in an electroluminescent device architecture of an ITO/PEDOT:PSS/TFB/CQD:PVK/TPBi/LiF/Al structure and blended with poly(N-vinylcarbazole) (PVK) to evaluate their ability to reach white electroluminescent emission. Results confirmed a high external quantum efficiency (EQE) of 0.76% and a maximum luminescence of 774.3 cd<middle dot>m(-2). Tuning the ratio between CQDs and PVK from 1:10.25 to 1:5.75 resulted in a systematic shift in CIE x-y coordinates from 0.23-0.26 to 0.21-0.24, located close to the cool white region. The results of the present study can be considered a step forward in fabricating efficient WLEDs based on low-cost CQDs.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.