WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 16Citation - Scopus: 16Exploiting the Lability of Metal Halide Perovskites for Doping Semiconductor Nanocomposites(American Chemical Society, 2021) Calcabrini, Mariano; Genç, Aziz; Liu, Yu; Kleinhanns, Tobias; Lee, Seungho; Dirin, Dmitry N.; Akkerman, Quinten A.Cesium lead halides have intrinsically unstable crystal lattices and easily transform within perovskite and nonperovskite structures. In this work, we explore the conversion of the perovskite CsPbBr3 into Cs4PbBr6 in the presence of PbS at 450 degrees C to produce doped nanocrystal-based composites with embedded Cs4PbBr6 nanoprecipitates. We show that PbBr2 is extracted from CsPbBr3 and diffuses into the PbS lattice with a consequent increase in the concentration of free charge carriers. This new doping strategy enables the adjustment of the density of charge carriers between 10(19) and 10(20) cm(-3), and it may serve as a general strategy for doping other nanocrystal-based semiconductors.Article Citation - WoS: 44Citation - Scopus: 38The Importance of Surface Adsorbates in Solution-Processed Thermoelectric Materials: The Case of Snse(Wiley, 2021) Liu, Yu; Calcabrini, Mariano; Yu, Yuan; Genç, Aziz; Chang, Cheng; Costanzo, Tommaso; Kleinhanns, TobiasSolution synthesis of particles emerges as an alternative to prepare thermoelectric materials with less demanding processing conditions than conventional solid-state synthetic methods. However, solution synthesis generally involves the presence of additional molecules or ions belonging to the precursors or added to enable solubility and/or regulate nucleation and growth. These molecules or ions can end up in the particles as surface adsorbates and interfere in the material properties. This work demonstrates that ionic adsorbates, in particular Na+ ions, are electrostatically adsorbed in SnSe particles synthesized in water and play a crucial role not only in directing the material nano/microstructure but also in determining the transport properties of the consolidated material. In dense pellets prepared by sintering SnSe particles, Na remains within the crystal lattice as dopant, in dislocations, precipitates, and forming grain boundary complexions. These results highlight the importance of considering all the possible unintentional impurities to establish proper structure-property relationships and control material properties in solution-processed thermoelectric materials.Article Citation - WoS: 40Citation - Scopus: 44Plasmon-Enhanced Photocatalytic and Antibacterial Activity of Gold Nanoparticles-Decorated Hematite Nanostructures(Elsevier Ltd., 2021) Emre, Alp; İmamoğlu, Rizvan; Savacı, Umut; Turan, Servet; Kazmalı, M. Kürşat; Genç, AzizHematite (alpha-Fe2O3) nanoparticles have received significant attention from the researchers due to their favorable and desirable properties in diverse applications. In the present study, single-crystalline hematite pseudo-nanocubes and porous nanorods were synthesized by the hydrothermal route without the usage of any surfactant agents, which were then decorated with gold nanoparticles hidrothermally in an aqueous solution in order to increase the solar energy conversion efficiency. The photocatalytic activities of synthesized nanoparticles were studied against Rhodamine B (RhB) under the illumination of AM 1.5 solar simulator. The excellent photocatalytic efficiency was obtained by changing morphological features of hematite nanostructures, along with the photocatalytic performance enhancement up to 25% thanks to the surface plasmon resonances for the gold nanoparticles-decorated hematite nanostructures. For instance, gold-nanoparticles decorated hematite pseudo-nanocubes almost completely degraded all the RhB after 30 min of illumination. It was also observed that all hematite products, with and without gold decoration, exhibited an impressive antibacterial effect and showed the lethal effect in E.coli. The same nanoparticles being photocatalytically active for organic pollutant degradation and having antibacterial effect may have a good potential for waste water remediation applications. (C) 2020 Elsevier B.V. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3Green Fabrication of Lanthanide-Doped Hydroxide-Based Phosphors: Y(oh)(3):eu3+ Nanoparticles for White Light Generation(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2019) Güner, Tuğrul; Kuş, Anılcan; Özcan, Mehmet; Genç, Aziz; Şahin, Hasan; Demir, Mustafa MuammerPhosphors can serve as color conversion layers to generate white light with varying optical features, including color rendering index (CRI), high correlated color temperature (CCT), and luminous efficacy. However, they are typically produced under harsh synthesis conditions such as high temperature, high pressure, and/or by employing a large amount of solvent. In this work, a facile, water-based, rapid method has been proposed to fabricate lanthanide-doped hydroxide-based phosphors. In this sense, sub-micrometer-sized Y(OH)(3):Eu3+ particles (as red phosphor) were synthesized in water at ambient conditions in <= 60 min reaction time. The doping ratio was controlled from 2.5-20 mol %. Additionally, first principle calculations were performed on Y(OH)(3):Eu3+ to understand the preferable doping scenario and its optoelectronic properties. As an application, these fabricated red phosphors were integrated into a PDMS/YAG:Ce3+ composite and used to generate white light. The resulting white light showed a remarkable improvement (approximate to 24%) in terms of luminous efficiency, a slight reduction of CCT (from 3900 to 3600 K), and an unchanged CRI (approximate to 60) as the amount of Y(OH)(3):Eu3+ was increased.Article Citation - WoS: 18Citation - Scopus: 14Optimization and Performance of Nitrogen-Doped Carbon Dots as a Color Conversion Layer for White-Led Applications(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2019) Güner, Tuğrul; Yüce, Hürriyet; Taşçıoğlu, Didem; Şimşek, Eren; Savacı, Umut; Genç, Aziz; Demir, Mustafa MuammerIn this study, green-emitting nitrogen-doped carbon dots (N-CDots) were synthesized and incorporated into drop-cast composite films for use as color conversion layers in a white-LED configuration to generate white light. In order to resolve the red deficiency of this configuration, a commercial red phosphor was integrated into the system. Moreover, the N-CDots were also processed into polymer/N-CDot composite fibers, for which we determined the amount of N-CDots that yielded adequate white-light properties. Finally, we showed that white light with excellent properties could be generated by employing both of the fabricated N-CDot composites either as drop-cast films or composite fibers. Hence, N-CDots provide a promising alternative to inorganic phosphors that are commonly employed in white-LED configurations.Article Citation - WoS: 39Citation - Scopus: 39Polarized Emission From Cspbbr3 Nanowire Embedded-Electrospun Pu Fibers(IOP Publishing Ltd., 2018) Güner, Tuğrul; Topçu, Gökhan; Savacı, Umut; Genç, Aziz; Sarı, Emre; Demir, Mustafa MuammerInterest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ∼4 nm thick CsPbBr3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr3 NWs showed a remarkable increase in the degree of polarization from 0.17-0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.