Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
Browse
6 results
Search Results
Article Anisotropic Tunability of Vibrational Modes in Black Phosphorus Under Uniaxial Compressive/Tensile Strain(Wiley, 2023) Li, Hao; Kutlu, Tayfun; Carrascoso, Felix; Şahin, Hasan; Munuera, Carmen; Castellanos Gomez, AndresStrain engineering is a powerful strategy for tuning the optical, electrical, vibrational properties of 2D nanomaterials. In this work, a four-point bending apparatus is constructed to apply both compressive and tensile strain on 2D anisotropic black phosphorus flake. Further polarized Raman spectroscopy is used to study the vibrational modes of black phosphorus flakes under uniaxial strain applied along various crystalline orientations. Here, a strong anisotropic blue/redshift of A1g, B2g, and A2g modes is found under compressive/tensile strain, respectively. Interestingly, mode A1g exhibits the maximum/minimum shift while mode B2g and mode A2g present the minimum/maximum shift when the strain is applied along armchair/zigzag direction. Density functional theory calculations are carried out to investigate the anisotropic strain response mechanism, finding that the strain-induced regulation of the PP bond angle, bond length, and especially interlayer interaction has a giant influence on the Raman shift. A four-point bending apparatus is constructed to study the effect of uniaxial strain on the vibrational property of anisotropic black phosphorus. Particularly, strong anisotropy on the Raman blueshift/redshift rate upon compressive/tensile strain can be observed, which results from the strain-induced regulation of the bond angle, bond length, and interlayer interactions according to density functional theory calculation analysis.imageArticle Citation - WoS: 3Citation - Scopus: 3Influence of Cation Size and Polarity on Charge Transport in Ionic Liquid Based Electrolytes(Wiley, 2022) Aydın, Banu; Öner, Saliha; Zafer, Ceylan; Varlıklı, CananImidazolium-based ionic liquids (ILs) with allyl and ether side chains were synthesized and characterized. Comprehensive structural and photoelectrochemical characterizations were performed, transport properties of ILs were also examined as electrolyte components in dye sensitized solar cells (DSSCs). The properties of synthesized materials and DSSC performances were compared with 1-propyl-3-methyl imidazolium iodide (PMII) and 1-allyl-3-ethyl imidazolium iodide (AEII) as reference ILs. Ionic conductivities, diffusion coefficients and charge transfer resistances of synthesized ionic liquids were investigated on DSSCs by Electrochemical Impedance Spectroscopy (EIS). The diffusion coefficient values of triiodide ions in different ionic liquid-based electrolytes were measured by the means of diffusion limited current density method and found to be 1.75×10−7 cm2 s−1 and 2.05×10−7 cm2 s−1 with corresponding photocurrent densities of 10.38 mAcm−2 and 12.13 mAcm−2 for the reference AEII and PMII based electrolytes, respectively. However, for the electrolytes of 1-(2-methoxyethyl)-3-allyl imidazolium iodide and 1-allyl-3-methyl imidazolium iodide ionic liquids, these values were found to be 0.86×10−7 cm2 s−1 and 0.57×10−7 cm2 s−1 with photocurrent densities of 9.53 mAcm−2 and 8.98 mAcm−2, respectively. Allyl and ether substituted imidazolium ILs exhibited promising results as potential alternative electrolyte materials for DSSCs.Article Citation - WoS: 4Citation - Scopus: 3Hg(ii)-Mediated Intramolecular Cyclization of Alkynyl Hydrazones: Towards a New Reaction-Based Sensing Approach for Hg(ii) Ions(Wiley, 2022) Tütüncü, Büşra Buse; Cebeci, Miray; Emrullahoğlu, MustafaDrawing upon an intramolecular cyclization/annulation reaction sequence mediated by Hg2+ ions, a BODIPY-based fluorescent probe decorated with an alkynyl hydrazone motif responds rapidly and selectively to Hg2+ ions, with a detection limit of 29 nM and a fluorescence turn-on ratio of 15-fold. With the addition of Hg2+ ions, the BODIPY-based alkynyl hydrazone transforms into a pyrazole ring to mediate a turn-on emission response clearly observable to the naked eye under visible light excitation.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: 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: 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.