Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
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Article Citation - WoS: 5Citation - Scopus: 5Thickness-Dependent Piezoelecticity of Black Arsenic From Few-Layer To Monolayer(Elsevier, 2023) Akgenç Hanedar, Berna; Ersan, Fatih; Altalhi, Tariq; Yağmurcukardeş, Mehmet; Yakobson, BorisUltra-thin forms of black phosphorus (b-P) have been widely investigated due to its unique properties arising from the in-plane anisotropy in its crystal structure. Recently, two-dimensional (2D) forms of black arsenic (b-As) have also been added to the 2D family. In this study, the thickness-dependent structural, electronic, and piezoelectric properties of layered b-As are investigated by means of ab-initio calculations. The structural optimizations confirm the van der Waals type layered structure for both these structures. In addition, increasing the thickness is shown to result in the decreasing of the band gap arising from the confinement of electrons in the layers. In contrast to the case of b-P, it is revealed that a transition from indirect-to-direct band gap behavior can be found in b-As which can be important for optically identifying the single-layer structure. Moreover, the piezoelectric properties are investigated as a function of the number of layers. It is shown that while a single-layer of b-As does not exhibit piezoelectric features, even in the case of bilayer structures the piezoelectricity is created. Our results revealed the strong in-plane anisotropy in piezoelectric coefficients for the three-layer and thicker structures. We have shown that the out-of-plane piezoelectric properties can be achieved by non-centrosymmetric features in the out-of-plane direction in thicker structures of b-As.Article Citation - WoS: 4Citation - Scopus: 4A Cyclopalladated Bodipy Construct as a Fluorescent Probe for Carbon Monoxide(Wiley, 2022) Çevik Eren, Merve; Eren, Ahmet; Dartar, Suay; Tütüncü, Büşra Buse; Emrullahoğlu, MustafaBy introducing a palladium ion into the backbone of BODIPY, we devised a cyclopalladated BODIPY construct that was almost non-emissive in the absence of any analyte but became highly fluorescent upon interacting with carbon monoxide (CO) in solution and in living cells. A process of ortho-carbonylation and depalladation mediated by the specific binding of CO to palladium, promoted the release of the heavy atom from the fluorophore and consequently generated a fluorescence signal with an exceptionally high (60-fold) enhancement ratio.Article Citation - WoS: 3Citation - Scopus: 1Transition Metal Salt Promoted, Green, and High-Yield Synthesis of Silver Nanowires for Flexible Transparent Conductive Electrodes(Wiley-Blackwell, 2021) Sarısözen, Sema; Tertemiz, Necip Ayhan; Arıca, Tuğçe Aybüke; Polat, Nahit; Kocabaş, Çoşkun; Mert Balcı, Fadime; Balcı, SinanSilver nanowires (AgNWs) have attracted considerable interest from both academia and industry owing to their excellent electrical, optical, and chemical properties. For large-scale synthesis of AgNWs, the polyol method involving ethylene glycol, a toxic alcohol, has been widely used. We herein report on a facile, green, high yield, transition metal salt promoted, open atmosphere method for the synthesis of high quality AgNWs in a glycerol-water mixture. We have shown that transition metal salts have a strong influence on the morphology of AgNWs. Importantly, in the presence of copper(II) chloride, AgNWs with a high aspect ratio of around 400 (length, 36 μm; diameter, 90 nm) were obtained. Additionally, for the first time, we have demonstrated AgNWs based flexible transparent conductive electrodes (TCEs) on poly(sodium 4-styrenesulfonate) (PSS) treated polyethylene terephthalate (PET) substrate with a sheet resistance of 34 Ω/sq and transmittance of 91 % at 550 nm. The PSS layer on the PET substrate generated a highly hydrophilic surface, which boosts interaction of AgNWs with the PET surface. We envision that our results would play a significant role both in the synthesis of AgNWs with high aspect ratio and also in designing new rigid and flexible TCEs having high transmittance and low sheet resistance for applications especially in printable solar cells, organic light emitting diodes, and high performance flexible electronics.Article Citation - WoS: 2Citation - Scopus: 2A New Fluorescent 'turn On' Probe for Rapid Detection of Biothiols(Taylor and Francis Ltd., 2020) Üçüncü, Muhammed; Zeybek, Hüseyin; Karakuş, Erman; Üçüncü, Canan; Emrullahoğlu, MustafaWe designed and synthesised a novel molecular probe exhibiting high selectivity and sensitivity towards reactive sulphur species (RSS) over other amino acids and biologically relevant species, as well as scrutinised its spectroscopic behaviours under physiological conditions and in living milieu. We used an electrophilic cyanate group as a masking agent to block the excited state intramolecular proton transfer process of 2-(2-cyanato-3-methoxyphenyl)benzo[d]thiazole (HMBT-OCN), which readily hydrolyses to the highly fluorescent structure, 2-(2'-Hydroxy-3'-methoxyphenyl) benzothiazole (HMBT-OH), in the presence of reactive sulphur species. [GRAPHICS] .Article Citation - WoS: 21Citation - Scopus: 25Surface Functionalization of the Honeycomb Structure of Zinc Antimonide (znsb) Monolayer: a First-Principles Study(Elsevier, 2021) Bafekry, A.; Shahrokhi, M.; Yağmurcukardeş, Mehmet; Gogova, D.; Ghergherehchi, M.; Akgenç, B.; Feghhi, S. A. H.Structural, electronic, optic and vibrational properties of Zinc antimonide (ZnSb) monolayers and their func-tionalized (semi-fluorinated and fully chlorinated) structures are investigated by means of the first-principles calculations. The phonon dispersion curves reveal the presence of imaginary frequencies and thus confirm the dynamical instability of ZnSb monolayer. The calculated electronic band structure corroborates the metallic character with fully-relativistic calculations. Moreover, we analyze the surface functionalization effect on the structural, vibrational, and electronic properties of the pristine ZnSb monolayer. The semi-fluorinated and fully-chlorinated ZnSb monolayers are shown to be dynamically stable in contrast to the ZnSb monolayer. At the same time, semi-fluorination and fully-chlorination of ZnSb monolayer could effectively modulate the metallic elec-tronic properties of pristine ZnSb. In addition, a magnetic metal to a nonmagnetic semiconductor transition with a band gap of 1 eV is achieved via fluorination, whereas a transition to a semiconducting state with 1.4 eV band gap is found via chlorination of the ZnSb monolayer. According to the optical properties analysis, the first ab-sorption peaks of the fluorinated-and chlorinated-ZnSb monolayers along the in-plane polarization are placed in the infrared range of spectrum, while they are in the middle ultraviolet for the out-of-plane polarization. Interestingly, the optically anisotropic behavior of these novel monolayers along the in-plane polarizations is highly desirable for design of polarization-sensitive photodetectors. The results of the calculations clearly proved that the tunable electronic properties of the ZnSb monolayer can be realized by chemical functionalization for application in the next generation nanoelectronic devices.Article Citation - WoS: 7Citation - Scopus: 8Seed-Mediated Synthesis of Colloidal 2d Halide Perovskite Nanoplatelets(Wiley, 2021) Güvenç, Çetin Meriç; Balcı, SinanColloidal synthesis of two-dimensional lead halide perovskite nanoplatelets (2D LHP NPLs) with a general formula of L-2[APbX(3)](n-1)PbX4 has been widely performed by using hot-injection or ligand assisted reprecipitation methods. Herein, for the first time, we report on seed-mediated synthesis of two and three monolayers (n=2, 3) lead halide perovskite nanoplatelets without using A-site cation halide salt (AX; A=Cesium, methylammonium, formamidinium and, X=Cl, Br, I) and long chain alkylammonium halide salts (LX; L=oleylammonium, octylammonium, butylammonium and, X=Cl, Br, I). The nanocrystal seeds have been prepared by reacting lead (II) halide salt and coordinating ligands in a nonpolar solvent and then they have been reacted with cesium oleate, formamidinium oleate or methylamine. Our facile synthesis route enabling further understanding of the growth dynamics of LHP NPLs provides highly stable, monodisperse NPLs with very narrow absorption and emission linewidths (min. 68 meV), and high PLQY (max. 37.6%).Article Citation - WoS: 3Citation - Scopus: 4Soluble Cytotoxic Ruthenium(ii) Complexes With 2-Hydrazinopyridine(Pleiades Publishing, 2019) Soliman, A. A.; Attaby, F. A.; Alajrawy, O., I; Majeed, S. R.; Şahin, C.; Varlıklı, CananNew water soluble Ru(II) binary complex [Ru(C5H7N3)(X)(H2O)(2)] with 2-hydrazinopyridine and its ternary complexes with X = dichloride, oxalate, malonate or pyrophosphate ligands have been synthesized. The complexes have been characterized using elemental analyses, mass, IR, and UV-Vis. spectroscopies, cyclic voltammetry, magnetic susceptibility, and thermal analysis. The complexes are diamagnetic and the electronic spectral data showed that peaks are due to low spin octahedral Ru(II) complexes. The optimized structures of the complexes 1-4 indicate distorted octahedral geometry with bond angles around the ruthenium atom ranged from 80.44 degrees to 99.64 degrees. The values of the electronic energies (-635 to -1145 a.u.), the highest occupied molecular orbital energies (-0.181 to 0.073 a.u.) and lowest unoccupied molecular orbital energies (-0.056 to 0.167 a.u.) indicate the stability of the complexes. The complexes are polarized as indicated from the dipole moment values (9.39-14.27 Debye). The complexes have noticeable cytotoxicity with IC50 (mu M): 0.011-0.062 (HepG-2), 0.015-0.080 (MCF-7), 0.015-0.116 (HCT-116), and PC-3 (0.034-0.125).Article Citation - WoS: 31Citation - Scopus: 34Highly Efficient Supercapacitor Using Single-Walled Carbon Nanotube Electrodes and Ionic Liquid Incorporated Solid Gel Electrolyte(SAGE Publications, 2018) Siyahjani, Shirin; Öner, Saliha; Singh, Pramod K.; Varlıklı, CananGel polymer electrolyte (GPE) comprising a low viscosity ionic liquid, that is, 1-propyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl)imide (PMI-TFSI, viscosity 38 cP at 20°C) and a polymer, that is, polyvinyl alcohol (PVA) have been prepared using solution cast technique and characterized by impedance spectroscopy, X-ray diffraction, differential scanning calorimetry, optical microscopy, and Fourier transform infrared spectroscopy. Blending PMI-TFSI with PVA matrix hindered the crystallinity of polymer matrix and presented remarkable enhancement in electrical conductivity with a conductivity maxima at 250 wt% PMI-TFSI. The prepared electric double-layer capacitor using single-walled carbon nanotube as symmetric electrodes and PVA:250 wt% PMI-TFSI as GPE presented a capacitance value of about 28 F g−Article Citation - WoS: 3Citation - Scopus: 3Monolayer Aste2: Stable Robust Metal in 2d, 1d and 0d(Wiley, 2018) Badalov, S. V.; Kandemir, Ali; Şahin, HasanThe structural, phononic, and electronic properties of the monolayer structures of AsTe2 are characterized by performing density functional theory (DFT) calculations. Total energy optimization and phonon calculations reveal that single layers of the 2H-AsTe2 and 1T-AsTe2 phases form dynamically stable crystal structures. Electronic structure analysis also shows that both 2H and 1T phases have nonmagnetic metallic character. It is also predicted that the metallic nature of the ultra-thin both 2H-AsTe2 and 1T-AsTe2 structures remain unchanged even under high biaxial strain values. For further examination of the dimensionality effect in the robust metallicity in 2D AsTe2 phases, electronic characteristics of 1D nanoribbons and 0D quantum dots are also investigated. It is found that independent from the dimension and crystallographic orientations 0D and 1D structures of 2H- and 1T-AsTe2 structures have metallic behavior. It is found that single layers of AsTe2 are quite promising materials for nanodevice applications owing to the robust metallic character.Article Citation - WoS: 12Citation - Scopus: 11Theoretical and Experimental Investigation of Conjugation of 1,6-Hexanedithiol on Mos2(IOP Publishing Ltd., 2018) Gül, Aytaç; Bacaksız, Cihan; Ünsal, Emre; Akbalı, Barış; Tomak, Aysel; Zareie, Hadi M.; Şahin, HasanWe report an experimental and theoretical investigation of conjugation of 1,6-Hexaneditihiol (HDT) on MoS2 which is prepared by mixing MoS2 structure and HDT molecules in proper solvent. Raman spectra and the calculated phonon bands reveal that the HDT molecules bind covalently to MoS2. Surface morphology of MoS2/HDT structure is changed upon conjugation of HDT on MoS2 and characterized by using Scanning Electron Microscope (SEM). Density Functional Theory (DFT) based calculations show that HOMO-LUMO band gap of HDT is altered after the conjugation and two-S binding (handle-like) configuration is energetically most favorable among three different structures. This study displays that the facile thiol functionalization process of MoS2 is promising strategy for obtaining solution processable MoS2.