scholarly journals Effects of Temperature and Host Concentration on the Supramolecular Enantiodifferentiating [4 + 4] Photodimerization of 2-Anthracenecarboxylate through Triplet-Triplet Annihilation Catalyzed by Pt-Modified Cyclodextrins

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1502 ◽  
Author(s):  
Ming Rao ◽  
Wanhua Wu ◽  
Cheng Yang
Keyword(s):  
Light Emitting Diode ◽  
Temperature Dependency ◽  
Light Emitting ◽  
Modified Cyclodextrins ◽  
Direct Irradiation ◽  
Visible Light Driven ◽  
Significant Temperature ◽  
Effects Of Temperature ◽  
532 Nm ◽  
Triplet Triplet Annihilation

Visible-light-driven photocatalytic supramolecular enantiodifferentiating dimerization of 2-anthracenecarboxylic acid (AC) through triplet-triplet annihilation (TTA), mediated by the Schiff base Pt(II) complex (Pt-1, Pt-2, and Pt-3) was studied. The host concentration and the temperature effects on the stereoselectivity were comprehensively investigated. Increasing the concentration of sensitizers/hosts significantly enhanced the conversion of the photoreaction but led to reduced enantioselectivities of the chiral photodimers 2 and 3 when the photoreaction was triggered by a 532 nm laser, which was in contrast with the results obtained by direct irradiation of AC with a 365 nm light-emitting diode (LED) lamp, due to the aggregation of the sensitizer/host in water. The cyclization of AC through triplet-triplet annihilation displayed significant temperature dependency when Pt-3 was employed as the sensitizer/host. Increasing the temperature from 0 °C to 30 °C with 5% equiv. of Pt-3 led to a great increase of the ee of 2 from 2.1% to 31.6%. However, hardly any temperature dependency was observed when the photodimerization was mediated by other sensitizers and/or hosts, or the photoreaction was triggered directly with a 365 nm LED lamp.

scholarly journals Determination of 3,4,5-Trihydroxybenzoic Acid Exploiting a Visible-Light-Driven Photoelectrochemical Platform: Application in Wine and Tea Samples

2022 ◽  
Author(s):  
Kayni Lima ◽  
Ridvan Fernandes ◽  
Clenilton dos Santos ◽  
Flavio Damos ◽  
Rita de Cássia Luz
Keyword(s):  
Light Emitting Diode ◽  
Glass Slide ◽  
Experimental Conditions ◽  
Amperometric Determination ◽  
Light Emitting ◽  
Promising Tool ◽  
Visible Light Driven ◽  
Photoelectrochemical Method ◽  
Acid Determination

The present work is based on the development and application of a photoelectrochemical method for the amperometric determination of 3,4,5-trihydroxybenzoic acid in different samples. The method is based on the use of a photoelectrochemical platform based on a glass slide coated with fluorine-doped tin oxide, which has been modified with cadmium sulfide and poly(D-glucosamine) and subjected to a light-emitting diode (LED) lamp. The photoelectrochemical platform was sensitive to the increase of the concentration of the antioxidant 3,4,5-trihydroxybenzoic acid in the solution. Under the optimized experimental conditions, the photoelectrochemical method presented a linear response for a 3,4,5-trihydroxybenzoic acid concentration ranging from 0.2 up to 500 μmol L-1. The method was applied to 3,4,5-trihydroxybenzoic acid determination in samples of wines and teas with recoveries between 95.88 and 101.72%. The results obtained suggest that the developed platform is a promising tool for quantifying the 3,4,5-trihydroxybenzoic acid.

scholarly journals Visible-Light-Driven Photocatalytic Activity of Magnetic BiOBr/SrFe12O19 Nanosheets

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 735 ◽  
Author(s):  
Taiping Xie ◽  
Jiao Hu ◽  
Jun Yang ◽  
Chenglun Liu ◽  
Longjun Xu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electron Microscope ◽  
Visible Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Active Species ◽  
Composite Catalyst ◽  
Light Emitting ◽  
Transmission Electron ◽  
Visible Light Driven

Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB.

scholarly journals Hermetic Seal of Organic Light Emitting Diode with Glass Frit

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 76
Author(s):  
Chien-Liang Chiu ◽  
Meng-Syun Lin ◽  
Yi-Chen Wu
Keyword(s):  
Power Efficiency ◽  
Light Emitting Diode ◽  
Glass Frit ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Hermetic Sealing ◽  
Hermetic Seal ◽  
20 Nm ◽  
532 Nm ◽  
A Current

The components of OLED encapsulation with hermetic sealing and a 1026-day lifetime were measured by PXI-1033. The optimal characteristics were obtained when the thickness of the TPBi layer was 20 nm. This OLED obtained a maximum luminance (Lmax) of 25,849 cd/m2 at a current density of 1242 mA/cm2, an external quantum efficiency (EQE) of 2.28%, a current efficiency (CE) of 7.20 cd/A, and a power efficiency (PE) of 5.28 lm/W. The efficiency was enhanced by Lmax 17.2%/EQE 0.89%/CE 42.1%/PE 41.9%. The CIE coordinates of 0.32, 0.54 were all green OLED elements with wavelengths of 532 nm. The shear strain and leakage test gave results of 16 kgf and 8.92 × 10−9 mbar/s, respectively. The reliability test showed that the standard of MIL-STD-883 was obtained.

scholarly journals Visible Light-Driven p-Type Semiconductor Gas Sensors Based on CaFe2O4 Nanoparticles

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 850
Author(s):  
Qomaruddin Qomaruddin ◽  
Olga Casals ◽  
Andris Šutka ◽  
Tony Granz ◽  
Andreas Waag ◽  
...  
Keyword(s):  
Visible Light ◽  
Gas Sensors ◽  
Light Emitting Diode ◽  
Ethanol Exposure ◽  
Desorption Process ◽  
Light Emitting ◽  
Type Semiconductor ◽  
Visible Light Driven ◽  
Calcium Iron ◽  
P Type

In this work, we present conductometric gas sensors based on p-type calcium iron oxide (CaFe2O4) nanoparticles. CaFe2O4 is a metal oxide (MOx) with a bandgap around 1.9 eV making it a suitable candidate for visible light-activated gas sensors. Our gas sensors were tested under a reducing gas (i.e., ethanol) by illuminating them with different light-emitting diode (LED) wavelengths (i.e., 465–640 nm). Regardless of their inferior response compared to the thermally activated counterparts, the developed sensors have shown their ability to detect ethanol down to 100 ppm in a reversible way and solely with the energy provided by an LED. The highest response was reached using a blue LED (465 nm) activation. Despite some responses found even in dark conditions, it was demonstrated that upon illumination the recovery after the ethanol exposure was improved, showing that the energy provided by the LEDs is sufficient to activate the desorption process between the ethanol and the CaFe2O4 surface.

Ultimate limit and temperature dependency of light-emitting diode efficiency

2009 ◽  
Vol 105 (9) ◽  
pp. 093119 ◽  
Author(s):  
Oskari Heikkilä ◽  
Jani Oksanen ◽  
Jukka Tulkki
Keyword(s):  
Light Emitting Diode ◽  
Temperature Dependency ◽  
Light Emitting ◽  
Ultimate Limit

Exciton dynamics in heterojunction thin-film devices based on exciplex-sensitized triplet–triplet annihilation

2018 ◽  
Vol 20 (43) ◽  
pp. 27449-27455 ◽  
Author(s):  
Nathan T. Tierce ◽  
Chia-Hsun Chen ◽  
Tien-Lung Chiu ◽  
Chi-Feng Lin ◽  
Christopher J. Bardeen ◽  
...  
Keyword(s):  
Thin Film ◽  
Light Emitting Diode ◽  
Blue Emission ◽  
Diode Structure ◽  
Blocking Layer ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Thin Film Devices ◽  
Triplet Triplet Annihilation

A triplet-diffusion-singlet-blocking layer and fluorescent dopant enhance blue emission due to triplet–triplet annihilation in an organic light emitting diode structure.

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