Search results for "Photoluminescence"
showing 10 items of 811 documents
Doping induced stable room temperature dual emission from gadolinium doped vacancy ordered double halide perovskite, Gd:Cs2SnCl6
2022
The recent advancement in bandgap engineering through controlled doping has widen the prospectof vacancy ordered double halide perovskites (VO DHPs) by conferring them with designableoptoelectronic properties. Here, we report synthesis of Gd doped Cs2SnCl6 via a simplesolvothermal method. Gd3+ ions doping lowers the band gap from 3.8 eV to 2.8 eV and facilitatesstable room temperature dual PL emission centered at 440 nm and 610 nm. The macroscopicemission process is well supported by the confocal PL emission studies on isolated crystallites.Both the pristine (Cs2SnCl6) and Gd:Cs2SnCl6 exhibit crystalline cubic structure with Fm3m spacegroup. Rietveld refinement correlates well with the cubi…
Synthesis, structural and luminescent properties of Mn-doped calcium pyrophosphate (Ca2P2O7) polymorphs
2022
The study was partially funded by the Swedish Research Council FORMAS project “Utilization of solid inorganic waste from the aquaculture industry as wood reinforcement material for flame retardancy” (grant no. 2018-01198). Vilnius University is highly acknowledged for financial support from the Science Promotion Foundation (MSF-JM-5/2021). This project has also received funding from European Social Fund (project No 09.3.3-LMT-K-712-19-0069) under grant agreement with the Research Council of Lithuania (LMTLT). The authors acknowledge the Center of Spectroscopic Characterization of Materials and Electronic/Molecular Processes ("SPECTROVERSUM" www.spectroversum.ff.vu.lt ) at the Lithuanian Nat…
Glass-forming non-symmetric bis-styryl-DWK-type dyes for infra-red radiation amplification systems
2019
Abstract A series of D-π-A type organic dyes with bulky triphenylmethyl moiety containing 2,6-bis-(4-substituted)styryl-4H-pyran-4-ylidene donor (D) fragments and different electron acceptors (A) were synthesized and investigated, mostly for potential applications in organic solid-state lasers as infra-red (IR) radiation amplification medium. Dye glass transition temperature is above 99 °C with thermal stability in the region from 173 °C to 326 °C which was slightly influenced by the electron acceptor fragment attached to the 4H-pyrane ring in 4-position. Introducing substituents in 4-position within one of the styryl-fragments with stronger electron withdrawing properties decreased ASE exc…
Solid state solvation effect and reduced amplified spontaneous emission threshold value of glass forming DCM derivative in PMMA films
2015
Abstract Molecule crystallization is one of the limitations for obtaining high-gain organic laser systems. One of the examples is well known red laser dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The lowest threshold value of amplified spontaneous emission was achieved by doping 2 wt% of DCM molecule in tris-(8-hydroxy quinoline) aluminum (Alq3) matrix. Further increase of the DCM dye concentration makes the system less efficient as its threshold value increases. It is due to large intermolecular interaction, which induces photoluminescence quenching. Compounds with reduced intermolecular interaction could be prospective in organic laser systems due to higher …
Glassy 2-(1-benzyl-2-styryl-6-methylpyridin-4(1H)-ylidene) fragment containing 1H-indene-1,3(2H)-dione and pyrimidine-2,4,6(1H,3H,5H)-trione derivati…
2020
A series of 2-(1-benzyl-2-(styryl)-6-methylpyridin-4(1H)-ylidene) fragment containing glassy organic compounds have been synthesized from relevant luminescent 4H-pyran-4-ylidene derivatives and investigated as potential solution processable emitters. Glass transition temperatures of synthesized 1H-pyridine compounds are above 100°C with thermal stabilities higher than 260°C. In the solutions of dichloromethane their absorption bands are in the range from 350 nm to 500 nm with photoluminescence from 500 nm to 650 nm. In a contrary to the 4H-pyran-4-ylidene derivatives, the incorporation of various electron acceptor fragments within the 1H-pyridine fragment containing molecules only slightly …
UV-patternable nanocomposite containing CdSe and PbS quantum dots as miniaturized luminescent chemo-sensors
2015
In this study, a novel multifunctional hybrid polymer-based luminescent material, particularly formulated for photolithography, was developed, fabricated and tested as a miniaturized chemosensor. This nanocomposites were formulated with either luminescent CdSe (for the visible) or PbS (for the near-IR) colloidal QDs embedded in a polyisoprene-based photoresist (PIP). We checked the sensing capability of the nanocomposite by exposing 1 cm2 CdSe nanocomposite patterns to vapours of some analyte solutions such as 2-mercaptoethanol (MET) and ethylenediamine (EDA). The transduction mechanism of the sensor is based on changes of the QD photoluminescence (PL) when molecules are adsorbed on the QD …
Water-soluble, cyclodextrin-functionalized semiconductor nanocrystals: Preparation and pH-dependent aggregation and emission properties
2009
Abstract Using peramino-functionalized β-cyclodextrin molecules for phase.transfer of hydrophobic CdSe multishell nanocrystals into water, we obtained hydrophilic nanoparticles with high quantum yield (up to 50%). At pH > 9, the aqueous solution of these nanocrystals remained stable for several months. The nanoparticles showed a strong influence of the pH of the aqueous solution on the emission of the nanocrystals: the quantum yield varied reversible from ∼10% at pH=6 to ∼50% at pH=14, an effect which according to particle size characterization by dynamic light-scattering and asymmetric flow field-flow fractionation has mainly been attributed to reversible partial aggregation of the hydroph…
Multilayer Thin Films by Layer-by-Layer Assembly of Hole- and Electron-Transport Polyelectrolytes: Optical and Electrochemical Properties
2006
In this paper, we pressent the synthesis of a series of p-type and n-type semicondnctring polyelectrolytes with triarylamine, oxadiazole, thiarliazole and triazine moictes. The synthesized polymeric hole and electrom iransport materials were examined optically and electrochemically using UV/Vis spectroscopy. PL spectroscopy and CV. Based on the optical and electrochemical data, each of the energy levels were calculated and all values suggested that the were promising hole-(p-type) or alectron=transprot (n-type) materials for devices. Moreover, the synthesized ionie polymers were suitable for LBL thin film deposition from ditute polymer solutions and the multilayers were fully characterized …
Multilayers of CdSe/CdS/ZnCdS Core/Wings/Shell Nanoplatelets Integrated in a Polymer Waveguide
2017
In this work, fabrication of multilayers of colloidal CdSe/CdS/ZnCdS core/wings/shell nanoplatelets (NPls) on solid substrates by layer-by-layer deposition technology is successfully demonstrated for the first time. Integration of multilayers of nanoplatelets into polymeric waveguide resulted in strong dichroism in absorption and polarization effects in photoluminescence with preferable absorption and emission of TE (horizontal) mode that evidences about in-plane orientation of NPls relative to the planar waveguide. The propagation of the excitation and emission light along the waveguide was thoroughly investigated both theoretically and experimentally for different number of NPl layers.
Molecular Iodine for a General Synthesis of Binary and Ternary Inorganic and Hybrid Organic-inorganic Iodide Nanocrystals
2018
We report the synthesis of various binary and ternary inorganic and hybrid organic–inorganic iodide nanocrystals (NCs) starting from molecular iodine (I2). The synthesis described herein utilizes a reaction between I2 and oleylamine, which results in oleylammonium iodide, an iodide precursor that can be directly used in the preparation of iodide-based NCs. The generality of the synthesis was demonstrated by synthesizing KI, RbI, CsI, AgI, CsPbI3, FAPbI3, Cs4PbI6, Cs3Bi2I9, FA3Bi2I9, and RbAg4I5 NCs. Furthermore, the syntheses are facile and are carried out in vials heated on a hot plate in air. They exhibit not only narrow size distributions, but also, in the case of lead-based perovskites …