Vitrimer enhanced carbazole-based organic room-temperature phosphorescent materials

2021 ◽  
Author(s):  
Tianqi Xu ◽  
Peng Wu ◽  
Lingyun Lou ◽  
Yuzhan Li ◽  
Dong Wang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Radiative Transition ◽  
Quantum Yields

Organic room-temperature phosphorescent(RTP) materials have promising applications, but due to the lack of inter-system scaling and susceptibility to non-radiative transition, they typically have low quantum yields (<2%) and short lifetimes...

scholarly journals The behaviour of visual purple at low temperature

1941 ◽  
Vol 179 (977) ◽  
pp. 151-159 ◽  
Keyword(s):  
Aqueous Solution ◽  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Absorption Curve ◽  
Quantum Yields

Visual purple is soluble and stable in a mixture of glycerol and water (3:1). At room temperature the spectrum of such a solution is identical with that of the aqueous solution. At — 73° C the peak of the absorption curve is higher and narrower than at room temperature, and it is shifted towards longer waves. The product of photodecomposition at — 73° C has a spectrum in ­ dependent of pH and is at low temperatures thermostable and photostable, but at room temperature it decomposes therm ally to indicator yellow. The primary product appears to be identical with transient orange. The quantum yields of the photoreaction at low and at room temperature are of the same order.

scholarly journals Regioisomeric Effect on the Excited-State Fate Leading to Room-Temperature Phosphorescence or Thermally Activated Delayed Fluorescence in a Dibenzophenazine-Cored Donor–Acceptor–Donor System

2021 ◽  
Author(s):  
Takumi Hosono ◽  
Nicolas Oliveira Decarli ◽  
Paola Zimmermann Crocomo ◽  
Tsuyoshi Goya ◽  
Leonardo Evaristo de Sousa ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Room Temperature Phosphorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
Emission Behavior

Exploring design principle for switching thermally activated dealyed fluorescecne (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies on the regioisomeric and substituents effects in a twisted donor–acceptor–donor (D–A–D) scaffold (A = dibenzo[a,j]phenazine; D = dihydrophenazasiline) on the fate of the excited state have been performed. The study revealed that the regiosiomerism clearly affects the emission behavior of the D–A–D compounds. Distinct difference in TADF, dual TADF & RTP, and dual RTP were observed, depending on the host used. Furthermore, OLED organic light-emitting diodes (OLEDs) fabricated with the developed emitters achieved high external quantum yields for RTP-based OLEDS up to 7.4%.

scholarly journals Rare earths (Ce, Eu) molar concentration-dependent of the structural and optical properties of CBD-CdS nanofilms

2018 ◽  
Vol 64 (3) ◽  
pp. 240 ◽  
Author(s):  
Joel Diaz-Reyes ◽  
Jorge Indalecio Contreras-Rascón ◽  
Mariana Enelia Linares-Avilés ◽  
José Francisco Sánchez-Ramírez ◽  
José Eladio Flores-Mena ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Rare Earths ◽  
Room Temperature ◽  
Longitudinal Mode ◽  
Radiative Transition ◽  
Molar Concentration ◽  
Raman Shift ◽  
Interstitial Oxygen ◽  
Synthesis Time ◽  
X Ray

It presents the characterization of rare earths (Eu,Ce)-doped CdS nanofilms that were synthesised by the growth technique chemical bath deposition (CBD) at the reservoir temperature of 70±2°C. The doping of CdS with rare earths is performed by varying the synthesis time from 60 to 135 min. The rare earths molar concentration was range from 0.0≤x≤3.5, which was determined by energy dispersive X-ray spectroscopy. X-ray diffraction (XRD) analysis and Raman scattering reveal that CdS nanofilms showed the zinc blende (ZB) crystalline phase. The CdS average nanocrystal size was ranged from 1.84 to 2.67 nm that was determined by the Debye–Scherrer equation from ZB (111) direction, which was confirmed by transmission electron microscopy. Raman scattering shows that the lattice dynamics is characteristic of bimodal behaviour and the multipeaks adjust of the first optical longitudinal mode for the (Eu,Ce)-doped CdS, which denotes the Raman shift of the characteristic peak about 305 cm−1 of the CdS nanocrystals. The CdS nanofilms exhibit a direct bandgap that slightly decreases with increasing doping, from 2.50 to 2.42 eV, which was obtained by room temperature transmittance. The room-temperature photoluminescence of CdS shows the band-to-band transition at 2.88 eV, which is associated to quantum confinement and a dominant radiative band at 2.37 eV that is called the optical signature of interstitial oxygen. The Eu3+-doped CdS photoluminescence shows the dominant radiative band at 2.15 eV, which is associated to the intra-4f radiative transition of Eu3+ ions that corresponds to the magnetic dipole transition, (5D0→7F1). For the Ce3+-doped CdS the dominant radiative transition, at 2.06 eV, is clearly redshifted, although the passivation of the CdS nanofilms by Ce was approximately by a factor about 21 for the best results.

Reactions of Thiyl Radicals. XI. Further Investigations of Thiol–Disulfide Photolyses in the Liquid Phase

1973 ◽  
Vol 51 (9) ◽  
pp. 1410-1415 ◽  
Author(s):  
Donna D. Carlson ◽  
Arthur R. Knight
Keyword(s):  
Liquid Phase ◽  
Room Temperature ◽  
Liquid Mixtures ◽  
Quantum Yields ◽  
Chain Reaction ◽  
Photochemical Process ◽  
High Quantum Efficiency ◽  
Thiyl Radicals ◽  
Exchange Processes ◽  
A Chain

The photolysis of C2H5SH liquid at 2537 Å has been shown to give H2 and C2H5SSC2H5 at equal rates with a quantum yield of 0.25. The photolysis of ethanethiol – methyl disulfide liquid mixtures leads, via a chain reaction involving propagation by attack of thiyl radicals on the disulfide S—S bond, to the formation with high quantum efficiency of CH3SH, C2H5SSC2H5 and, as an intermediate that is consumed after long exposures, CH3SSC2H5. The net result of the sequence of exchange processes is the essentially irreversible conversion of the methyl disulfide into methanethiol. The same overall reaction occurs thermally at room temperature, but the rate is appreciably less than that of the photochemical process. The quantum yields of formation of the unsymmetrical disulfides arising from the photochemically initiated exchange reaction in equimolar mixtures of CH3SSCH3 + n-C3H7SSC3H7 and C2H5SSC2H5 + n-C3H7SSC3H7 have been shown to be 6.9 and 4.4, compared to 355 for CH3-SSCH3 + C2H5SSC2H5 mixtures. In all three types of system examined in this investigation all thiyl radicals can be accounted for stoichiometrically on the basis of exchange and combination reactions alone, indicating negligible disproportionation of these species in condensed phase.

Phytofluors: Phytochrome-Based Orange Fluorescent Protein Probes

1999 ◽  
Vol 5 (S2) ◽  
pp. 1050-1051
Author(s):  
J. Clark Lagarias ◽  
Beronda L. Montgomery ◽  
John T. Murphy ◽  
Shu-Hsing Wu
Keyword(s):  
Room Temperature ◽  
Fluorescent Protein ◽  
Protein Complexes ◽  
Quantum Yields ◽  
Color Intensity ◽  
Photosynthetic Organisms ◽  
Orange Fluorescent Protein ◽  
Pigment Protein Complexes ◽  
Covalently Linked ◽  
Light Color

Plants sense the light environment using pigment-protein complexes that discriminate light color, intensity, duration and direction. The most well-studied of these photoreceptors are the phytochromes, a family of soluble biliproteins found in plants, algae and cyanobacteria. Owing to the linear tetrapyrrole pigment phytochromobilin (PΦB) or phycocyanobilin (PCB) that is covalently linked to a large polypeptide via a thioether linkage, phytochromes perceive differences in the quality and quantity of light via their ability to photointerconvert between red (λmax660 nm) and far-red (λmax730 nm) light absorbing forms. Due to an efficient Z,E photoisomerization of the double bond between the C and D-ring pyrroles, phytochromes are nonfluorescent proteins with fluorescent quantum yields less than 10“3 at room temperature (Figure 1).Phytochrome genes have been cloned from a wide variety of photosynthetic organisms.

Photochemische 2+2-Cycloadditionen von Äthylen und Acetylen an 1.3-Cyclohexadien unter erhöhtem Druck / Photochemical 2+2-Cycloadditions of Ethylene and Acetylene to 1,3-Cyclohexadiene under High Pressure

1977 ◽  
Vol 32 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Marlis F. Mirbach ◽  
Manfred J. Mirbach ◽  
Alfons Saus
Keyword(s):  
High Pressure ◽  
Quantum Yield ◽  
Room Temperature ◽  
Kinetic Scheme ◽  
Solvent Mixture ◽  
Experimental Results ◽  
Quantum Yields ◽  
Ethylene Pressure ◽  
Formal Kinetic

The photochemical cycloaddition of 1,3-cyclohexadiene (CHD) to ethylene and acetylene at pressures above 10 bar is described. Upon sensitized irradiation (2-acetylnaphthaline) CHD adds to ethylene at room temperature in dichloromethane to give cis-bicyclo[4,2,0]-oct-2-ene (1) along with dimers of cyclohexadiene. The yield of cross adduct increases with ethylene pressure (10-50 bar) whereas dimerisation decreases. Quantum yields of cross addition and dimerisation at 12 M ethylene were determined to be 0.31 and 0.35 respectively. At a pressure of 15 bar acetylene CHD reacts with acetylene to give bicyclo-[4,2,0]octa-2,7-diene (2) and bicyclo[2,2,2]octa-2,5-diene (3) as the major and minor products respectively. In a solvent mixture containing 60 vol-% CH2Cl2 and 40 vol-% acetone (2) is formed with a quantum yield of φ = 0.2. The experimental results are explained by a formal kinetic scheme.

A facile one-pot synthesis of deep blue luminescent lead bromide perovskite microdisks

2015 ◽  
Vol 51 (91) ◽  
pp. 16385-16388 ◽  
Author(s):  
Zhao Yuan ◽  
Yu Shu ◽  
Yu Tian ◽  
Yan Xin ◽  
Biwu Ma
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Quantum Yields ◽  
Synthetic Method ◽  
Lateral Size ◽  
One Pot ◽  
One Pot Synthesis ◽  
Deep Blue ◽  
Lead Bromide

We report a facile one-pot synthetic method to prepare highly luminescent layered lead(ii) bromide perovskite microdisks with the lateral size of a few micrometers and thickness of 100–150 nm, featuring narrow deep blue emissions with quantum yields of up to 53% in toluene solutions and thin films at room temperature.

Interatomic radiative transition of a valence electron to inner core: Luminescence from Cs-Halides and RbF at room temperature

1988 ◽  
Vol 40-41 ◽  
pp. 149-150 ◽  
Author(s):  
Shinzou Kubota ◽  
Jian-zhi Ruan(Gen) ◽  
Shiro Sakuragi ◽  
Minoru Itoh ◽  
Satoshi Hashimoto
Keyword(s):  
Room Temperature ◽  
Valence Electron ◽  
Inner Core ◽  
Radiative Transition

The Quantum Yield of Oxidation of Hevea Rubber and GR-S

1948 ◽  
Vol 21 (3) ◽  
pp. 639-653 ◽  
Author(s):  
E. J. Hart ◽  
M. S. Matheson
Keyword(s):  
Quantum Yield ◽  
Room Temperature ◽  
Wave Length ◽  
Radical Reaction ◽  
Quantum Yields ◽  
Initial Reaction ◽  
Free Radical Reaction ◽  
Stable Intermediate ◽  
A Chain ◽  
Reaction Chain

Abstract The initial quantum yields of photoöxidation for purified Hevea rubber have been measured for various mercury arc lines in the wave length region 2537– 17,400 A˚. All experiments were carried out at room temperature and at an oxygen pressure of one atmosphere. At the outset of irradiation all quantum yields of combined oxygen are less than unity, although the quantum efficiency rises above 1.0 at 2537 and 3130 A˚. as photoöxidation proceeds. The low quantum yield suggests that in its initial stages (less than 0.1 per cent oxygen combined on the rubber) photoöxidation is not a chain reaction. It is postulated as the first step in rubber photoöxidation that the light activated rubber group reacts with oxygen to give a relatively stable intermediate which does not immediately dissociate to give a free radical reaction chain. The quantum yields of photoöxidation of purified GR-S were also measured under the same conditions as used for rubber. At each wave length the quantum yield was lower than for rubber, indicating formation of a stable intermediate in the initial reaction also.

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