Search results for "Photoluminescence"

Short-range order and luminescence in amorphous silicon oxynitride

2000

Abstract Using Si 2p core-level X-ray photoelectron spectroscopy, we found that the short-range order in amorphous silicon oxynitride (a-SiOxNy) can be quantitatively described by a random bonding model. Results also show that the second and even further neighbours of the Si in the network affect the chemical shifts of the X-ray photoelectron spectra. Cathodoluminescence and photoluminescence of a-SiOxNy with different compositions are also measured. A red band with energies of 1.8–1.9 eV, a blue band with an energy of 2.7 eV and ultraviolet bands with energies of 13.1, 3.4–3.6, 4.4–4.7 and 5.4eV were observed. The 1.8–1.9 eV band is attributed to the O and N atoms with an unpaired electron…

Solution processable piperazine and triphenyl moiety containing non-symmetric bis-styryl-DWK type molecular glasses with light-emitting and amplified…

2018

A series of 2,6-bis-styryl-4H-pyran-4-ylidene fragment containing glassy organic compounds with chemically stable bonding of amorphous phase promoting bulky triphenyl moieties through piperazine structural fragment (DWK-T dyes) in a form of 2-(5,5,5-triphenylpentyl)piperazin-1-yl)styryl)-substituent have been synthesized and investigated as the potential gain medium component for organic solid state laser applications. Physical properties of the dyes vary and are mostly depending from the other styryl-substituent attached to the 4H-pyran-4-ylidene backbone fragment in 6-position. Thermal stability of synthesized dyes is above 312°C with the glass transitions from 97°C to 109°C. Obtained nea…

Glass-forming derivatives of 2-cyano-2-(4H-pyran-4-ylidene) acetate for light-amplification systems

2019

Abstract A series of 2-cyano-2-(4H-pyran-4-ylidene) acetate derivatives with triphenyl and 9H-carbazole moieties were synthesized and investigated, mostly for potential applications in organic solid state lasers. Synthesized compounds show remarkable amorphous film formation ability, tunable thermal properties (thermal stability varies from 190 °C to 387 °C and glass transition temperature from 94 °C up to 141 °C) with light absorption from 400 nm to 600 nm and photoluminescence from 600 nm up to 800 nm. Dyes with incorporated mono-styryl- electron donating fragment (KTB, KTBC and KTB3K) showed higher photoluminescence quantum yield (PLQY) (from 16% up to 23%), significantly lower amplified…

Amplified spontaneous emission of pyranyliden derivatives in PVK matrix

2016

One of the well-known red light emitting laser dyes is 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4Hpyran ( DCM ). Amplified spontaneous emission (ASE) has been widely investigated of DCM molecules or its derivatives in polymer or low molecular weight matrix. The main issue for these molecules is aggregation which limits doping concentration in matrix. Lowest ASE threshold values within concentration range of 2 and 4 wt% were obtained. In this work ASE properties of two original DCM derivatives in poly(N-vinylcarbazole) ( PVK ) at various concentrations will be discussed. One of the derivatives is the same DCM dye with replaced butyl groups at electron donor part with bulky try…

Optical and amplified spontaneous emission of neat films containing 2-cyanoacetic derivatives

2018

During the last two decades, small organic molecules have been widely studied for potential applications in organic solid-state lasers due to low-cost production, simple processing possibility and physical property tuning ability through chemical structure synthetic modifications. One of the most investigated and applied compound in dye lasers is 4- (dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). It has shown remarkable properties as a dye in solid-state lasers. One of the drawbacks of this compound is high intermolecular interactions which reduce emission efficiency. Therefore it can be applied only in doped systems in low concentration (around 2 wt%). Recently we hav…

Temperature dependence of Photoluminescence and Amplified Spontaneous Emission in thin films of quasi-2D BA3MA3Pb5Br16 perovskites

2021

Stimulated emission and optical properties of pyranyliden fragment containing compounds in PVK matrix

2017

This work has been supported by National Research program “Multifunctional materials and composites, photonics and nanotechnology (IMIS2)”. Financial support provided by Scientific Research Project for Students and Young Researchers No. SJZ2015/12 realised at the Institute of Solid State Physics, University of Latvia is greatly acknowledged.

Amplified Spontaneous Emission in Thin Films of CsPbX3 Perovskite Nanocrystals

2019

During the last years, Metal Halide Perovskites (MHPs) have attracted special attention as an efficient conversion films for photovoltaics, or excellent gain media to construct optical sources. In spite of the fact that most of the works have been focussed on CH 3 NH 3 PbX 3 (X=Cl, Br, I) polycrystalline thin films, MHP can be also synthesized as colloidal nanocrystals. In particular, caesium lead halide perovskite CsPbX 3 nanocrystals (NCs) revealed extraordinary properties for optoelectronics. With a high quantum yield of emission (>90%) at room temperature and linewidths less than 100 meV, CsPbX 3 NCs have demonstrated favourable characteristics for active photonics. Indeed, thin films o…

Amplified spontaneous emission in thin films of quasi-2D BA3MA3Pb5Br16 lead halide perovskites

2021

Quasi-2D (two-dimensional) hybrid perovskites are emerging as a new class of materials with high photoluminescence yield and improved stability compared to their three-dimensional (3D) counterparts. Nevertheless, despite their outstanding emission properties, few studies have been reported on amplified spontaneous emission (ASE) and a thorough understanding of the photophysics of these layered materials is still lacking. In this work, we investigate the ASE properties of multilayered quasi-2D BA3MA3Pb5Br16 films through the dependence of the photoluminescence on temperature and provide a novel insight into the emission processes of quasi-2D lead bromide perovskites. We demonstrate that the …

Concentration dependence of amplified spontaneous emission in two oligo-(p-phenylenevinylene) derivatives

2005

Amplified spontaneous emission sASEd in optically pumped polystyrene sPSd films doped with two different oligo-sp-phenylenevinylened derivatives sOPVsd, with three s3-OPVd and five s5-OPVd monomer units is reported. It is observed that there is a maximum content of oligomer s25 wt. % for 3-OPV and 20 wt. % for 5-OPVd that can be introduced in the films, due to degradation sin 3-OPVd and ASE quenching sin 5-OPVd. Optimal concentrations swith minimum pump-intensity thresholds for the observation of ASEd of 15 wt. % and 9 wt. % are measured for the trimer and the pentamer, respectively. The concentration dependence of the ASE threshold is discussed in terms of the optical absorption spectra. G…