WoS İndeksli Yayınlar Koleksiyonu

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

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Citation - WoS: 2
Citation - Scopus: 1
Benefiting From Both Ethanol Oxidation and Bidentate Thiol Groups of DHLA Ligands Under Photoirradiation for Synthesis of Au Nanoparticles With Their Catalytic and Peroxidase Like Activity
(Amer Chemical Soc, 2025) Temur, Nimet; Dadi, Seyma; Dogan, Ayse Nur; Nisari, Mustafa; Avan, Ilker; Ocsoy, Ismail
In this work, we rationally synthesized quite stable gold nanoparticles (AuNPs) using dihydrolipoic acid (DHLA) and DHLA-aspartame (DHLA-Asptm) as both reducing and stabilizing agents in a mixture of water/ethanol at RT under photoirradiation in 10 min. The novelty of this work is that benefiting from both the oxidation of ethanol to ethanal and having the bidentate thiol groups of DHLA, stable DHLA@AuNPs and DHLA-Asptm@AuNPs were successfully and rapidly formed without additional reducing reagents. We systematically examined the formation of DHLA@AuNPs and DHLA-Asptm@AuNPs under different pH values and reaction temperatures. Furthermore, the salt tolerance of DHLA@AuNPs and DHLA-Asptm@AuNPs was tested in a series of sodium chloride solutions. We showed the catalytic and peroxidase-like activities of DHLA@AuNPs against 4-nitrophenol and 3,3 ',5,5 '-tetramethylbenzidine. The AuNPs were characterized by UV-vis spectrophotometry, scanning transmission electron microscopy, zeta potential, and dynamic light scattering.
Citation - WoS: 14
Citation - Scopus: 14
Boosting the Ceramics With in Situ MOF- Derived Nanocarbons
(Amer Chemical Soc, 2023) Duden, Enes Ibrahim; Bayrak, Kubra Gurcan; Balkan, Mert; Cakan, Niyaz; Demiroglu, Arsen; Ayas, Erhan; Sen, Unal
Metal-organic framework (MOF)-derived nano-carbons have emerged as promising materials for energy and environmental applications owing to their high surface area, structural and chemical tunability, and hierarchical porosity. Although various carbon-based materials such as graphene and carbon nanotubes have been extensively used as secondary sintering additives to develop advanced ceramics with improved mechanical, thermal, and electrical properties, the potential of MOF-derived nanocarbon-based materials has not been ex-plored. Here, we report the first use of MOF-derived nanocarbons as a reinforcement phase in ceramic composites. To this end, Al2O3 and zeolitic imidazolate framework (ZIF-8) are used as the ceramic matrix and nanocarbon source, respectively. The ceramic composites are produced by densifying Al2O3 and ZIF-8 powder mixtures using spark plasma sintering (SPS) at 1550 degrees C and uniaxial pressure of 50 MPa. The fracture toughness of the composite increases up to 67% in comparison to an alumina monolith as ZIF-derived nanocarbons form interlayers to assist the dissipation of energy during the crack propagation and inhibit grain growth. The room-temperature electrical conductivity of the sintered samples drastically increases with the in situ formed nanocarbon-based fillers, reaching as high as 1410 S/m for 10 wt % ZIF-8 content. These results constitute an excellent initial step toward boosting the mechanical and electrical properties of ceramic matrix composites with in situ MOF-derived nanocarbons.
Citation - WoS: 44
Citation - Scopus: 44
Boronic Acid Moiety as Functional Defect in UiO-66 and Its Effect on Hydrogen Uptake Capacity and Selective Co2 Adsorption: a Comparative Study
(Amer Chemical Soc, 2018) Erkartal, Mustafa; Sen, Unal
Herein, we use linker fragmentation approach to introduce boronic acid moieties as functional defects into Zr-based metal organic frameworks (MOFs, UiO-66). Our findings show that the amount of permanently incorporated boronic acid containing ligand is directly dependent on the synthesis method. The accessible boronic acid moieties in the pore surfaces significantly improve the hydrogen uptake values, which are 3.10 and 3.44 wt % at 21 bar, 77 K for dimethylformamide (DMF)/H2O and DMF/HCI synthesis methods, respectively. Also, CO2 selectivity of the resulting MOFs over N-2 and CH4 significantly increases due to the quadrupolar interaction between active surfaces and CO2 molecules. To the best of our knowledge, both hydrogen storage and selectivity of CO2 for UiO-66 are the highest reported values in the literature to date. Furthermore, another striking result that emerged from the high-pressure hydrogen uptake isotherms is the direct correlation between the defects and hysteric adsorption behavior, which may result in the shift from rigidity to flexibility of the framework due to the uncoordinated sites.
Citation - WoS: 58
Citation - Scopus: 60
Cadmium-Free and Efficient Type-II InP/ZnO Quantum Dots and Their Application for Leds
(Amer Chemical Soc, 2021) Eren, Guncem Ozgun; Sadeghi, Sadra; Jalali, Houman Bahmani; Ritter, Maximilian; Han, Mertcan; Baylam, Isinsu; Nizamoglu, Sedat
It is a generally accepted perspective that type-II nanocrystal quantum dots (QDs) have low quantum yield due to the separation of the electron and hole wavefunctions. Recently, high quantum yield levels were reported for cadmium-based typeII QDs. Hence, the quest for finding non-toxic and efficient type-II QDs is continuing. Herein, we demonstrate environmentally benign type-II InP/ZnO/ZnS core/shell/shell QDs that reach a high quantum yield of similar to 91%. For this, ZnO layer was grown on core InP QDs by thermal decomposition, which was followed by a ZnS layer via successive ionic layer adsorption. The small-angle Xray scattering shows that spherical InP core and InP/ZnO core/ shell QDs turn into elliptical particles with the growth of the ZnS shell. To conserve the quantum efficiency of QDs in device architectures, InP/ZnO/ZnS QDs were integrated in the liquid state on blue light-emitting diodes (LEDs) as down-converters that led to an external quantum efficiency of 9.4% and a power conversion efficiency of 6.8%, respectively, which is the most efficient QD-LED using type-II QDs. This study pointed out that cadmium-free type-II QDs can reach high efficiency levels, which can stimulate novel forms of devices and nanomaterials for bioimaging, display, and lighting.
Citation - WoS: 16
Citation - Scopus: 17
Colloidal Aluminum Antimonide Quantum Dots
(Amer Chemical Soc, 2019) Jalali, Houman Bahmani; Sadeghi, Sadra; Sahin, Mehmet; Ozturk, Hande; Ow-Yang, Cleva W.; Nizamoglu, Sedat
AlSb is a less studied member of the III-V semiconductor family, and herein, we report the colloidal synthesis of AlSb quantum dots (QDs) for the first time. Different sizes of colloidal AlSb QDs (5 to 9 nm) were produced by the controlled reaction of AlCl3 and Sb[N(Si(Me)(3))(2)](3) in the presence of superhydride. These colloidal AlSb quantum dots showed excitonic transitions in the UV-A region and a tunable band edge emission (quantum yield of up to 18%) in the blue spectral range. Among all III-V quantum dots, these quantum dots show the brightest core emission in the blue spectral region.
Citation - WoS: 48
Citation - Scopus: 49
Colloidal Quantum Dot Light-Emitting Diodes Employing Phosphorescent Small Organic Molecules as Efficient Exciton Harvesters
(Amer Chemical Soc, 2014) Mutlugun, Evren; Guzelturk, Burak; Abiyasa, Agus Putu; Gao, Yuan; Sun, Xiao Wei; Demir, Hilmi Volkan
Nonradiative energy transfer (NRET) is an alternative excitation mechanism in colloidal quantum dot (QD) based electroluminescent devices (QLEDs). Here, we develop hybrid highly spectrally pure QLEDs that facilitate energy transfer pumping via NRET from a phosphorescent small organic molecule-codoped charge transport layer to the adjacent QDs. A partially codoped exciton funnelling electron transport layer is proposed and optimized for enhanced QLED performance while exhibiting very high color purity of 99%. These energy transfer pumped hybrid QLEDs demonstrate a 6-fold enhancement factor in the external quantum efficiency over the conventional QLED structure, in which energy transfer pumping is intrinsically weak.
Citation - WoS: 17
Citation - Scopus: 17
Comparison of Photocatalytic and Adsorption Properties of ZnS@ZnO, CdS@ZnO, and PbS@ZnO Nanocomposites to Select the Best Material for the Bifunctional Removal of Methylene Blue
(Amer Chemical Soc, 2025) Bayram, Umit; Ozer, Cigdem; Yilmaz, Erkan
In this study, photocatalytic- and adsorption-based removal processes were conducted, which are frequently preferred in wastewater treatment due to their ease of control and high removal efficiency. An innovative method aimed at wastewater treatment was developed by combining the advantages of these two distinct approaches within the same material. The study synthesized ZnO, ZnS, CdS, PbS, and their composite structures (ZnS@ZnO, CdS@ZnO, and PbS@ZnO) using a hydrothermal synthesis method. Characterization of the samples was performed through field emission-scanning electron microscopy (FE-SEM), FE-SEM-energy dispersive X-ray (FE-SEM-EDX), X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR) measurement. Additionally, the optical properties of all samples (absorption spectra and band gap) were investigated by using absorbance measurements obtained from ultraviolet (UV)-visible absorption spectroscopy. Although ZnO nanoparticles are among the materials with high photocatalytic properties (exhibiting a photodegradation efficiency of 95.8% in a short duration of 90 min), their adsorption properties are low. Therefore, with the aim of enhancing both the low adsorption values and the photocatalytic properties of pure metal sulfides (ZnS, CdS, PbS), nanocomposites ZnS@ZnO, CdS@ZnO, and PbS@ZnO with different morphologies were synthesized, and their photocatalytic and adsorption-based removal performances on methylene blue (MB) dye were investigated. FE-SEM images indicated that ZnS nanoparticles exhibit a spherical morphology, CdS nanoparticles have a flower-like morphology, and PbS nanoparticles display a dendritic-like structure. The results obtained from experimental studies demonstrated that the highest efficiency in both photocatalytic- and adsorption-based removal was achieved with the ZnS@ZnO nanocomposite. The degradation rates of MB were found to be 95.3, 90.5, and 89.4% for the heterojunction composites ZnS@ZnO, CdS@ZnO, and PbS@ZnO, respectively, over a time range of 0-480 min. The optimal amount of photocatalyst that could effectively degrade MB was determined to be 100 mg, and the reusability studies revealed that the ability of the ZnS@ZnO semiconductor heterojunction photocatalyst to decompose MB into simpler molecules was limited after the fourth cycle. The adsorption-based removal rates were 96.0, 30.5, and 19.4% for the heterojunction composites ZnS@ZnO, CdS@ZnO, and PbS@ZnO, respectively. Finally, parameters influencing the adsorption-based removal of MB, such as pH, mass, and contact time, were examined, indicating that the adsorption capacity of ZnS@ZnO remained unchanged after reaching a value of 40 mgg-1.
Design and Development of Functional Organic Small Molecules and Polymers for Optoelectronics
(Amer Chemical Soc, 2016) Usta, Hakan; Demirel, Gokhan; Facchetti, Antonio; Muccini, Michele
Determining Temperature Change on Photothermal Au Nanorod and Au Nanocage Using Smart Polymers
(Amer Chemical Soc, 2015) Buyukbekar, Burak Zafer; Cavusoglu, Halit; Sakalak, Huseyin; Citir, Murat; Demirel, Gokhan; Yavuz, Mustafa Selman
Citation - WoS: 51
Citation - Scopus: 52
Dicarboxylic Acids Induced Tandem Transformation of Silver Nanocluster
(Amer Chemical Soc, 2023) Wang, Zhi; Gupta, Rakesh Kumar; Alkan, Fahri; Han, Bao-Liang; Feng, Lei; Huang, Xian-Qiang; Sun, Di
Structural transformation of metal nanoclusters (NCs) is of great ongoing interest regarding their synthesis, stability, and reactivity. Although sporadic examples of cluster transformations have been reported, neither the underlying transformation mechanism nor the intermediates are unambiguous. Herein, we have synthesized a flexible 54-nuclei silver cluster (Ag54) by combining soft ((BuC)-Bu-t=C-) and hard ((PrCOO-)-Pr-n) ligands. The existence of weakly coordinated nPrCOO(-) enhances the reactivity of Ag54, thus facilitating the dicarboxylic acid to induce structural transformation. X-ray structural analyses reveal that Ag54 transforms to Ag-28 cluster-based 2D networks (Ag28a and Ag28b) induced by H(2)suc (succinic acid) and H(2)glu (glutaric acid), whereas with H(2)pda (2,2'-(1,2-phenylene)diacetic acid), a discrete Ag-28 cluster (Ag28c) is isolated. The key intermediate Ag17 that emerges during the self-dissociation of Ag54 was isolated by using cryogenic recrystallization and characterized by X-ray crystallography. The "tandem transformation" mechanism for the structure evolution from Ag54 to Ag28a is established by time-dependent electrospray ionization mass spectrometry (ESIMS) and UV-vis spectroscopy. In addition, the catalytic activity in the 4-nitrophenol reduction follows the sequence Ag28c > Ag28b > Ag28a > Ag54 due to more bare silver sites on the surface of the Ag-28 cluster unit. Our findings not only open new avenues to the synthesis of silver NCs but also shed light on a better understanding of the structural transformation mechanism from one cluster to another or cluster-based metal-organic networks induced by dicarboxylates.
Discovery and in Silico Characterization of Anatolian Water Buffalo Rumen-Derived Bacterial Thermostable Xylanases: A Sequence-Based Metagenomic Approach
(Amer Chemical Soc, 2025) Kurt, Halil; Kaya, Dilek Sever; Akcok, Ismail; Sari, Ceyhun; Albayrak, Ebru; Velioglu, Hasan Murat; Surmeli, Yusuf
This study involved shotgun sequencing of rumen metagenomes from three Anatolian water buffalos, an exploration of the relationship between microbial flora and xylanases, and in silico analyses of thermostable xylanases, focusing on their sequence, structure, and dynamic properties. For this purpose, the rumen metagenome of three Anatolian water buffalos was sequenced and bioinformatically analyzed to determine microbial diversity and full-length xylanases. Analyses of BLAST, biophysicochemical characteristics, phylogenetic tree, and multiple sequence alignment were performed with Blastp, ProtParam, MEGA11 software, and Clustal Omega, respectively. Three-dimensional homology models of three xylanases (AWBRMetXyn5, AWBRMetXyn10, and AWBRMetXyn19) were constructed by SWISS-MODEL and validated by ProSA, ProCheck, and Verify3D. Also, their 3D models were structurally analyzed by PyMOL, BAN Delta IT, thermostability predictor, What If, and Protein Interaction Calculator (PIC) software. Protein-ligand interactions were examined by docking and MD simulation. Shotgun sequence and Blastp analyses showed that Clostridium (Clostridiales bacterial order), Ruminococcus (Oscillospiraceae bacterial family), Prevotella (Bacteroidales bacterial order), and Butyrivibrio (Lachnospiraceae bacterial family) were found as dominant potential xylanase-producer genera in three rumen samples. Furthermore, the biophysicochemical analysis indicated that three xylanases exhibited an aliphatic index above 80, an instability index below 40, and melting temperatures (T m) surpassing 65 degrees C. Phylogenetic analysis placed three xylanases within the GH10 family, clustering them with thermophilic xylanases, while homology modeling identified the optimal template as a xylanase from a thermophilic bacterium. The structural analysis indicated that three xylanases possessed the number of salt bridges, hydrophobic interactions, and T m score higher than 50, 165, and 70 degrees C, respectively; however, the reference thermophilic XynAS9 had 43, 145, and 54.41 degrees C, respectively. BAN Delta IT analysis revealed that three xylanases exhibited lower B '-factor values in the beta 3-alpha 1 loop/short-helix at the N-terminal site compared to the reference thermophilic XynAS9. In contrast, six residues (G79, M123, D150, T199, A329, and G377) possessed higher B '-factor values in AWBRMetXyn5 and their aligned positions in AWBRMetXyn10 and AWBRMetXyn19, relative to XynAS9 including Gln, Glu, Ile, Lys, Ser, and Val at these positions, respectively. MD simulation results showed that the beta 9-eta 5 loop including catalytic nucleophile glutamic acid in the RMSF plot of three xylanases had a higher fluctuation than the aligned region in XynAS9. The distance analysis from the MD simulation showed that the nucleophile residue in AWBRMetXyn5 and AWBRMetXyn10 remained closer to the ligand throughout the simulation compared with XynAS9 and AWBRMetXyn19. The most notable difference between AWBRMetXyn5 and AWBRMetXyn10 was the increased amino acid fluctuations in two specific regions, the eta 3 short-helix and the eta 3-alpha 3 loop, despite a minimal sequence difference of only 1.24%, which included three key amino acid variations (N345, N396, and T397 in AWBRMetXyn5; D345, K396, and A397 in AWBRMetXyn10). Thus, this study provided computational insights into xylanase function and thermostability, which could inform future protein engineering efforts. Additionally, three xylanases, especially AWBRMetXyn5, are promising candidates for various high-temperature industrial applications. In a forthcoming study, three xylanases will be experimentally characterized and considered for potential industrial applications. In addition, the amino acid substitutions (G79Q, M123E, D150I, T199K, A329S, and G377V) and the residues in the beta 3-alpha 1 loop will be targeted for thermostability improvement of AWBRMetXyn5. The amino acids (N345, N396, and T397) and the residues on the beta 9-eta 5 loop, eta 3 short-helix, and eta 3-alpha 3 loop will also be focused on development of the catalytic efficiency.
Citation - WoS: 2
Citation - Scopus: 2
Effect of Calcium Oxide on Stress Crack Resistance and Light Transmittance in PET Containers for Packaging Carbonated Beverages
(Amer Chemical Soc, 2024) Yuvali, Gokcen; Dagasan Bulucu, Esen; Demirel, Bilal; Yaras, Ali; Akkurt, Fatih; Surdem, Sedat; Demirel, Burcak
For polyethylene terephthalate (PET) bottles, a material used for food packaging, light transmission and mechanical performance, particularly environmental stress cracking (ESC), are essential characteristics. For this purpose, following extrusion of PET/CaO granules, preforms were manufactured using the injection technique, and bottles were produced by a stretch-blow-molding process. With incorporation of calcium oxide (CaO), light transmittance increased by around 25%, and ESC went from 0.3 to 11 min. In addition, whereas acetaldehyde (AA) and carboxylic acid (COOH) decomposition values rose with increasing CaO content, diethylene glycol and isophthalic acid values did not significantly change. Moreover, the maximum crystallization temperature and crystallinity both exhibited an upward trend with the CaO content.
Citation - WoS: 38
Citation - Scopus: 40
Effect of Molecular Architecture on Cell Interactions and Stealth Properties of PEG
(Amer Chemical Soc, 2017) Ozer, Imran; Tomak, Aysel; Zareie, Hadi M.; Baran, Yusuf; Bulmus, Volga
PEGylation, covalent attachment of PEG to therapeutic biomolecules, in which suboptimal pharmacokinetic profiles limiting their therapeutic utility are of concern, is a widely applied technology. However, this technology has been challenged by reduced bioactivity of biomolecules upon PEGylation and immunogenicity of PEG triggering immune response and abrogating clinical efficacy, which collectively necessitate development of stealth polymer alternatives. Here we demonstrate that comb-shape poly[oligo(ethylene glycol) methyl ether methacrylate](POEGMA); a stealth polymer alternative, has a more compact structure than PEG and self-organize into nanoparticles in a molecular weight dependent manner. Most notably, we show that comb shape POEGMA promotes significantly higher cellular uptake and exhibits less steric hindrance imposed on the conjugated biomolecule than PEG. Collectively, comb-shape POEGMA offers a versatile alternative to PEG for stealth polymer-biomolecule conjugation applications.
Citation - WoS: 61
Citation - Scopus: 62
Effective Neural Photostimulation Using Indium-Based Type-II Quantum Dots
(Amer Chemical Soc, 2018) Jalali, Houman Bahmani; Aria, Mohammad Mohammadi; Dikbas, Ugur Meric; Sadeghi, Sadra; Kumar, Baskaran Ganesh; Sahin, Mehmet; Nizamoglu, Sedat
Light-induced stimulation of neurons via photoactive surfaces offers rich opportunities for the development of therapeutic methods and high-resolution retinal prosthetic devices. Quantum dots serve as an attractive building block for such surfaces, as they can be easily functionalized to match the biocompatibility and charge transport requirements of cell stimulation. Although indium based colloidal quantum dots with type-I band alignment have attracted significant attention as a nontoxic alternative to cadmium-based ones, little attention has been paid to their photovoltaic potential as type-II heterostructures. Herein, we demonstrate type-II indium phosphide/zinc oxide core/shell quantum dots that are incorporated into a photoelectrode structure for neural photostimulation. This induces a hyperpolarizing bioelectrical current that triggers the firing of a single neural cell at 4 mu W mm(-2), 26-fold lower than the ocular safety limit for continuous exposure to visible light. These findings show that nanomaterials can induce a biocompatible and effective biological junction and can introduce a route in the use of quantum dots in photoelectrode architectures for artificial retinal prostheses.
Citation - WoS: 21
Citation - Scopus: 21
Efficient Forster Resonance Energy Transfer Donors of In(Zn)P/ZnS Quantum Dots
(Amer Chemical Soc, 2017) Altintas, Yemliha; Talpur, Mohammad Younis; Mutlugun, Evren
We demonstrate a detailed investigation of the effect of the type and concentration of zinc precursor on the optical properties of In(Zn)P/ZnS quantum dots. We achieved up to 87% quantum yield along with 54 nm emission bandwidth for the green emitters with changing the concentration of the Zn precursors. Employing efficient green emitters as the donor species, we demonstrated an efficient Forster resonance energy transfer (FRET) couple of green and red emitting InP-based quantum dots. With a FRET efficiency level of 70.3% achieved (analyzed from the donor lifetime with and without an acceptor), we further demonstrated the enhancement of the acceptor emission nearly twofold due to the energy transfer. Our results provide new insights toward the understanding of the excitonic interactions among donor and acceptor quantum dots of the III-V family for light harvesting applications.
Citation - WoS: 7
Citation - Scopus: 7
Enhancing the Properties of Yttria-Stabilized Zirconia Composites With Zeolitic Imidazolate Framework-Derived Nanocarbons
(Amer Chemical Soc, 2023) Cakan, Niyaz; Issa, Abduselam Abubeker; Alsalman, Hamza; Aliyev, Emin; Duden, Enes Ibrahim; Gurcan Bayrak, Kubra; Sen, Unal
Ceramic matrix composites (CMCs) reinforced with nanocarbon have attracted significant interest due to their potential to enhance mechanical, thermal, and electrical properties. Although the investigation of carbon-based materials such as graphene and carbon nanotubes as additives for advanced ceramics has been widespread, the utilization of metal-organic framework (MOF)-derived nanocarbons in CMCs remains largely unexplored. We extended our previous proof-of-concept investigations by demonstrating the effectiveness of a different type of MOF-derived carbon as a reinforcing phase in an alternative ceramic matrix. We employed spark plasma sintering (SPS) to consolidate yttria-stabilized zirconia (YSZ) and zeolitic imidazolate framework (ZIF-67) powder blends at 1300 degrees C and a uniaxial pressure of 50 MPa. YSZ serves as the ceramic matrix, whereas ZIF-67 serves as the nanocarbon source. The composite exhibits a highly significant improvement in fracture toughness with an increase of up to 13% compared to that of the YSZ monolith. The formation of ZIF-derived nanocarbon interlayers is responsible for the observed enhancement in ductility, which can be attributed to their ability to facilitate energy dissipation during crack propagation and inhibit grain growth. Furthermore, the room-temperature electrical conductivity of the sintered samples demonstrates a substantial improvement, primarily due to the in situ formation of nanocarbon-based fillers, reaching an impressive 27 S/m with 10 wt % ZIF-67 content. Based on the results, it can be inferred that the incorporation of in situ MOF-derived nanocarbons into CMCs leads to a substantial improvement in both the mechanical and electrical properties.
Citation - WoS: 2
Fully Inorganic Colloidal CsPbBr3 Perovskite Nanocrystals with Zn-Doping and Metal Oxide Encapsulation for Luminescent Display Panels
(Amer Chemical Soc, 2025) Khorasani, Azam; Soheyli, Ehsan; Mutlugun, Evren
Perovskite 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.
Citation - WoS: 99
Citation - Scopus: 103
Giant Alloyed Hot Injection Shells Enable Ultralow Optical Gain Threshold in Colloidal Quantum Wells
(Amer Chemical Soc, 2019) Altintas, Yemliha; Gungor, Kivanc; Gao, Yuan; Sak, Mustafa; Quliyeva, Ulviyya; Bappi, Golam; Demir, Hilmi Volkan
As an attractive materials system for high- Record-low optical gain threshold in giant-shell COWs performance optoelectronics, colloidal nanoplatelets (NPLs) benefit from atomic-level precision in thickness, minimizing emission inhomogeneous broadening. Much progress has been made to enhance their photoluminescence quantum yield (PLQY) and photostability. However, to date, layer-by-layer growth of shells at room temperature has resulted in defects that limit PLQY and thus curtail the 0.2 performance of NPLs as an optical gain medium. Here, we introduce a hot-injection method growing giant alloyed shells using an approach that reduces core/shell lattice mismatch and suppresses Auger recombination. Near-unity PLQY is achieved with a narrow full-width-at-half-maximum (20 nm), accompanied by emission tunability (from 610 to 650 nm). The biexciton lifetime exceeds 1 ns, an order of magnitude longer than in conventional colloidal quantum dots (CQDs). Reduced Auger recombination enables record-low amplified spontaneous emission threshold of 2.4 mu J cm(-2) under one-photon pumping. This is lower by a factor of 2.5 than the best previously reported value in nanocrystals (6 /kJ cm(-2) for CdSe/CdS NPLs). Here, we also report single-mode lasing operation with a 0.55 mu J cm(-2) threshold under two-photoexcitation, which is also the best among nanocrystals (compared to 0.76 mu J cm(-2) from CdSe/CdS CQDs in the Fabry-Perot cavity). These findings indicate that hot-injection growth of thick alloyed shells makes ultrahigh performance NPLs.
Citation - WoS: 7
Citation - Scopus: 7
Giant Negative Linear Compressibility, Isosymmetric Phase Transition, and Breathing Effect in a 3D Covalent Organic Framework
(Amer Chemical Soc, 2023) Erkartal, Mustafa
A set of remarkable piezo-mechanical properties, including isosymmetric phase transition, negative linear compressibility (NLC), and a breathing effect in a three-dimensional covalent organic framework (NPN-3), was uncovered using density functional theory. The pressure-induced first-order phase transition observed between 0.9 and 1 GPa is isosymmetric and irreversible. NPN-3 shows giant NLC along the c-axis (K-c = 42.04 TPa-1) prior to the phase transition. The high-density NPN-3-hd obtained as a result of the phase transition shows an exciting phase transition from a closed pore to an open pore under hydrostatic tensile pressure, similar to the breathing effect. These extraordinary piezo-mechanical attributes within NPN-3 can be attributed to the diamondoid (dia) topology, which is commonly found within flexible MOFs and COFs. Additionally, the remarkable adaptability of the tetraphenyl adamantane monomer to distinct conformations under pressure can be seen in these properties. These findings underscore the potential utility of COFs as materials for piezo-mechanical sensors and serve as a source of inspiration for further exploration into the intricate mechanical behaviors of COFs.
Citation - WoS: 65
Citation - Scopus: 66
High Electron Mobility in [1]Benzothieno[3,2-B][1]Benzothiophene Field-Effect Transistors: Toward N-Type BTBTs
(Amer Chemical Soc, 2019) Usta, Hakan; Kim, Dojeon; Ozdemir, Resul; Zorlu, Yunus; Kim, Sanghyo; Ruiz Delgado, M. Carmen; Kim, Myung-Gil
The first example of an n-type [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based semiconductor, D-(PhFCO)-BTBT, has been realized via a two-step transition metal-free process without using chromatographic purification. Physicochemical and optoelectronic characterizations of the new semiconductor were performed in detail, and the crystal structure was accessed. The new molecule exhibits a large optical band gap (similar to 2.9 eV) and highly stabilized (Delta E-LUMO = 1.54 eV)/pi-delocalized lowest unoccupied molecular orbital (LUMO) mainly comprising the BTBT pi-core and in-plane carbonyl units. The effect of out-of-plane twisted (64 degrees) pentafluorophenyl groups on LUMO stabilization is found to be minimal. Polycrystalline D(PhFCO)-BTBT thin films prepared by physical vapor deposition exhibited large grains (similar to 2-5 mu m sizes) and "layer-by-layer" stacked edge-on oriented molecules with an in-plane herringbone packing (intermolecular distances similar to 3.25-3.46 angstrom) to favor two-dimensional (2D) source-to-drain (S -> D) charge transport. The corresponding TC/BG-OFET devices demonstrated high electron mobilities of up to similar to 0.6 cm(2)/V.s and I-on/I-off ratios over 10(7)-10(8). These results demonstrate that the large band gap BTBT pi-core is a promising candidate for high-mobility n-type organic semiconductors and, combination of very large intrinsic charge transport capabilities and optical transparency, may open a new perspective for next-generation unconventional (opto)electronics.

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