scholarly journals New Phosphine Oxides as High Performance Near- UV Type I Photoinitiators of Radical Polymerization

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1671 ◽  
Author(s):  
Céline Dietlin ◽  
Thanh Tam Trinh ◽  
Stéphane Schweizer ◽  
Bernadette Graff ◽  
Fabrice Morlet-Savary ◽  
...  
Keyword(s):  
Light Absorption ◽  
High Performance ◽  
Uv Light ◽  
Quantum Yields ◽  
Type I ◽  
Phosphine Oxides ◽  
Absorption Properties ◽  
Light Emitting ◽  
Uv Visible ◽  
Led Irradiation

Carbazole structures are of high interest in photopolymerization due to their enhanced light absorption properties in the near-UV or even visible ranges. Therefore, type I photoinitiators combining the carbazole chromophore to the well-established phosphine-oxides were proposed and studied in this article. The aim of this article was to propose type I photoinitiators that can be more reactive than benchmark phosphine oxides, which are among the more reactive type I photoinitiators for a UV or near-UV light emitting diodes (LED) irradiation. Two molecules were synthesized and their UV-visible light absorption properties as well as the quantum yields of photolysis and photopolymerization performances were measured. Remarkably, the associated absorption was enhanced in the 350–410 nm range compared to benchmark phosphine oxides, and one compound was found to be more reactive in photopolymerization than the commercial photoinitiator TPO-L for an irradiation at 395 nm.

scholarly journals High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Zhang ◽  
Changjiu Sun ◽  
Tingwei He ◽  
Yuanzhi Jiang ◽  
Junli Wei ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Structural Characteristics ◽  
Quantum Yields ◽  
Research Directions ◽  
Light Emitting ◽  
Perovskite Materials ◽  
Quantum Confinement Effects ◽  
Semiconducting Properties

AbstractQuasi-two-dimensional (quasi-2D) perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation light-emitting diodes (LEDs). The outstanding optical properties originate from their structural characteristics. In particular, the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectric- and quantum-confinement effects; the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields (PLQYs), particularly at low excitation intensities. The review herein presents an overview of the inherent properties of quasi-2D perovskite materials, the corresponding energy transfer and spectral tunability methodologies for thin films, as well as their application in high-performance LEDs. We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs. The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.

Quantum Yields for the Photodegradation of Pollutants in Dilute Aqueous Solution: Phenol, 4-Chlorophenol and N-Nitrosodimethylamine

1996 ◽  
Vol 1 (2) ◽  
Author(s):  
Te-Fu L. Ho ◽  
James R. Bolton ◽  
Ewa Lipczynska-Kochany
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Quantum Yield ◽  
High Performance ◽  
Flash Photolysis ◽  
Quantum Yields ◽  
Visible Absorption ◽  
Dilute Aqueous Solution ◽  
Uv Visible ◽  
Photolysis Of Phenol

AbstractA broadband method has been applied to determine the quantum yields for the photochemical removal of three common pollutants: phenol, 4-chlorophenol and N-nitrosodimethylamine (NDMA) in dilute aqueous solution. Flash photolysis (xenon flash lamps) was used to cause a significant amount of photolysis without photolyzing intermediates. The analysis of reactant depletion following a single flash was carried out by high- performance liquid chromatography (HPLC) or UV/visible absorption spectroscopy. The method for determining quantum-yields employed p-benzoquinone as an actinometer and was validated by determining the average (200-400 nm) quantum yield for the generation of hydroxyl radicals from the photolysis of hydrogen peroxide (0.90 ± 0.10) and the quantum yields for the photolysis of phenol (0.13 ± 0.02) and 4-chlorophenol (0.24 ± 0.04). The values determined agree very well with the literature ones obtained with monochromatic radiation. The quantum yield for the direct photolysis of NDMA was found to be 0.11 ± 0.03 at neutral pH and 0.27 ± 0.02 at pH 2-4. Under conditions where hydrogen peroxide is the principal absorber, the NDMA quantum yield is 0.32 ± 0.04, independent of pH in the range 2-8.

scholarly journals BiVO3 : A Bi-based material with promising uv-visible light absorption properties

2017 ◽  
Vol 96 (16) ◽  
Author(s):  
C. S. Praveen ◽  
Lorenzo Maschio ◽  
Michel Rérat ◽  
V. Timon ◽  
M. Valant
Keyword(s):  
Visible Light ◽  
Light Absorption ◽  
Absorption Properties ◽  
Visible Light Absorption ◽  
Uv Visible

scholarly journals Edge stabilization in reduced-dimensional perovskites

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Na Quan ◽  
Dongxin Ma ◽  
Yongbiao Zhao ◽  
Oleksandr Voznyy ◽  
Haifeng Yuan ◽  
...  
Keyword(s):  
Structural Diversity ◽  
Continuous Illumination ◽  
Quantum Yields ◽  
Color Purity ◽  
Phosphine Oxides ◽  
Maximum Luminance ◽  
Light Emitting ◽  
Tunable Bandgap ◽  
Luminescence Color ◽  
Oxidative Attack

AbstractReduced-dimensional perovskites are attractive light-emitting materials due to their efficient luminescence, color purity, tunable bandgap, and structural diversity. A major limitation in perovskite light-emitting diodes is their limited operational stability. Here we demonstrate that rapid photodegradation arises from edge-initiated photooxidation, wherein oxidative attack is powered by photogenerated and electrically-injected carriers that diffuse to the nanoplatelet edges and produce superoxide. We report an edge-stabilization strategy wherein phosphine oxides passivate unsaturated lead sites during perovskite crystallization. With this approach, we synthesize reduced-dimensional perovskites that exhibit 97 ± 3% photoluminescence quantum yields and stabilities that exceed 300 h upon continuous illumination in an air ambient. We achieve green-emitting devices with a peak external quantum efficiency (EQE) of 14% at 1000 cd m−2; their maximum luminance is 4.5 × 104 cd m−2 (corresponding to an EQE of 5%); and, at 4000 cd m−2, they achieve an operational half-lifetime of 3.5 h.

Platinum-Functionalized Chiral Molecular Squares as Light-Emitting Materials

2004 ◽  
Vol 846 ◽  
Author(s):  
Lin Zhang ◽  
Yu-Hua Niu ◽  
Alex K.-Y. Jen ◽  
Wenbin Lin
Keyword(s):  
Mass Spectrometry ◽  
Luminous Efficiency ◽  
Quantum Yields ◽  
Bridging Ligands ◽  
Maximum Brightness ◽  
Light Emitting ◽  
Visible Luminescence ◽  
Molecular Squares ◽  
Uv Visible ◽  
C Nmr

ABSTRACTA family of new chiral metallocycles based on Pt(II) diimine metallocornors and bis(acetylene) bridging ligands have been synthesized, and characterized by a variety of techniques including 1H and 13C NMR, UV-visible, luminescence, infrared, and circular dichroism (CD) spectroscopies, and mass spectrometry. All metallocycles exhibit very strong phosphorescence with quantum yields of 8.3 to 15.7%. Chiral Pt(II)-based molecular squares were used as the light-emitting layer in multiplayer devices, and a maximum brightness of 5470 cd/m2 with a maximum luminous efficiency of 0.93 cd/A was achieved.

scholarly journals Enhancement of UV Excited Photoluminescence by Fabry-Perot Microcavity

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Chunxian Tao ◽  
Jun Ruan ◽  
Dong Liang ◽  
Zhaoxia Han ◽  
Liang He ◽  
...  
Keyword(s):  
Uv Light ◽  
Resonant Cavity ◽  
Fluorescence Emission ◽  
Light Emitting ◽  
Dielectric Mirror ◽  
Fabry Perot ◽  
Measurement Results ◽  
Phosphor Coating ◽  
Uv Visible ◽  
Higher Sensitivity

A light-emitting microcavity with the structure of dielectric mirror/phosphor coating/dielectric mirror for the enhancement of PL efficiency excited under UV light was designed and fabricated. The fluorescence emission of Lumogen S0795 coating within microcavity structure is significantly enhanced compared with the coating on bare substrate. The measurement results indicate the possibility of developing front illuminated CCD based on optical resonant cavity for UV-visible imaging with higher sensitivity.

Self-Poled Transparent and Flexible UV Light-Emitting Cerium Complex–PVDF Composite: A High-Performance Nanogenerator

2015 ◽  
Vol 7 (2) ◽  
pp. 1298-1307 ◽  
Author(s):  
Samiran Garain ◽  
Tridib Kumar Sinha ◽  
Prakriti Adhikary ◽  
Karsten Henkel ◽  
Shrabanee Sen ◽  
...  
Keyword(s):  
High Performance ◽  
Uv Light ◽  
Light Emitting

scholarly journals Transcriptome and metabolome analyses revealed that narrowband 280 and 310 nm UV-B induce distinctive responses in Arabidopsis

2021 ◽  
Author(s):  
Tomohiro Tsurumoto ◽  
Yasuo Fujikawa ◽  
Daisaku Ohta ◽  
Atsushi Okazawa
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Uv Light ◽  
Current Model ◽  
Phenylpropanoid Pathway ◽  
Metabolic Responses ◽  
Uv Resistance ◽  
Light Emitting ◽  
Uv Led ◽  
Uv Leds ◽  
Led Irradiation

SUMMARYIn plants, the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) perceives UV-B and induces UV-B responses including synthesis of UV-B absorbing phenolic compounds such as anthocyanins. UVR8 absorbs a range of UV-B (260–335 nm). However, the responsiveness of plants to each UV-B wavelength has not been intensively studied so far. Here, we performed transcriptome and metabolome analyses of Arabidopsis using UV light emitting diodes (LEDs) with peak wavelengths of 280 and 310 nm to investigate the differences in the wavelength-specific UV-B responses. Irradiation with both UV-LEDs induced gene expression of the transcription factor ELONGATED HYPOCOTYL 5 (HY5), which has a central role in the UVR8 signaling pathway. However, the overall transcriptomic and metabolic responses to 280 and 310 nm UV-LED irradiation were different. Most of the known UV-B-responsive genes, such as salicylic acid, jasmonic acid, and defense-related genes, responded only to 280 nm UV-LED irradiation. Lipids, polyamines and organic acids were the metabolites most affected by 280 nm UV-LED irradiation, whereas the effect of 310 nm UV-LED irradiation on the metabolome was considerably less. Enzymatic genes involved in the phenylpropanoid pathway upstream in anthocyanin biosynthesis were up-regulated only by 280 nm UV-LED irradiation. On the other hand, no enzymatic genes downstream in anthocyanin biosynthesis were induced by the UV-LEDs, but rather, they were down-regulated by 310 nm UV-LED irradiation. These results revealed that the responsivenesses of Arabidopsis to 280 and 310 nm UV-B were significantly different, suggesting that UV-B signaling is mediated by more complex pathways than the current model.

Fabrication of high performance of AlGaN/GaN-based UV light-emitting diodes

2002 ◽  
Vol 235 (1-4) ◽  
pp. 177-182 ◽  
Author(s):  
T Wang ◽  
Y.H Liu ◽  
Y.B Lee ◽  
Y Izumi ◽  
J.P Ao ◽  
...  
Keyword(s):  
High Performance ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Light Emitting

Ir/Ag reflector for high-performance GaN-based near UV light emitting diodes

2006 ◽  
Vol 133 (1-3) ◽  
pp. 26-29 ◽  
Author(s):  
Keun-Yong Ban ◽  
Hyun-Gi Hong ◽  
Do-Young Noh ◽  
Jung Inn Sohn ◽  
Dae-Joon Kang ◽  
...  
Keyword(s):  
High Performance ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Light Emitting ◽  
Ag Reflector
Sign in / Sign up

Export Citation Format

Share Document