Enhancement Of Photostability Research Articles

Enhancement of Photostability Ageing of Samarium Complexes in PMMA Films

AbstractIn this study, a set of β‐diketonate samarium(III) complexes–namely, [Sm(TTA)3Phen], [Sm(TTA)3DPEPO], [Sm(TTA)3Bipy], and [Sm(TTA)3Pyra]–has been synthesized and comprehensively characterized. Upon excitation, these complexes exhibit distinct emissions at 566 nm, 610 nm, 650 nm, and 710 nm, respectively, corresponding to the electronic transitions 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2, and 4G5/2→6H11/2. Notably, the most pronounced pinkish‐red emission is associated with the peak at 650 nm. Furthermore, the [Sm(TTA)3DPEPO] complex displays a remarkable photoluminescence quantum yield, reaching up to 15.77 % in a PMMA film matrix. The investigation also involved a prolonged examination lasting over 1200 hours, during which PMMA films doped with the samarium complexes were subjected to humidity and weather conditions to evaluate their photoluminescence stability. The results indicate consistent emissions throughout the humidity test, with an eventual cessation after 1200 hours–except in the case of [Sm(TTA)3Phen] under weather conditions. The enduring emission in this scenario is attributed to the robustness of the phenanthroline ligand, thus highlighting its role in enhancing the durability of the complex.

Activation of Solid-State Emission and Photostability through Molecular Confinement: The Case of Triptycene-Fused Quinacridone Dyes.

We report the facile, metal-free convergent synthesis and the characterization of novel quinacridone dyes in which two triptycene units end-cap and sterically confine the quinacridone chromophore. A precise comparison of the confined dyes with their known homologues reveals that the reduction of π-π interactions in triptycene-fused quinacridone dyes compared to classical quinacridone results not only in an increase of solubility and processability but also in an enhancement of fluorescence quantum yield and photostability in the solid state.

P‐86: Ultrathin High Dichroic Ratio Azo Dye Thin Film Prepared by Photo‐alignment and Its Photostability Enhancement

Ultrathin (<200nm) azo dye polarizing film with a high dichroic ratio (over 150) is developed by photo‐alignment methods. Polarizing film prepared by solution‐based process (post‐ photoalignment) and evaporation (in‐situ photo‐alignment) with a family of azo dye materials with slightly different molecular structures is explored. We study the photostability of these azo‐dye films against polarized light. Methods and factors of getting high dichroic ratio and high photostability polarizing films are discussed.

Hydrogel Lasers Via Supramolecular Host–Guest Complexation

AbstractSupramolecular host–guest complexes are dynamic systems composed of typically macrocyclic host molecules encapsulating smaller guest molecules. One of their applications is the selective encapsulation of fluorescent dye molecules to tackle quenching and photobleaching in solution. When extended to solid matrices, the efficiency of dyes can be especially poor, limiting their use in fluorescence‐based applications. Here it is demonstrated that supramolecular host–guest complexation in a hydrogel network allows readily tunable hydrogel‐based lasers. Poly(N‐isopropylacrylamide)‐based copolymer hydrogel is used with covalently linked Rhodamine B molecules. By controlled doping of cucurbit[7]uril as a host molecule in the hydrogel, it is shown that the fluorescent quantum yield increases from 17% to 51%, accompanied by 15‐fold enhancement in photostability. As proof of concept, a thin‐film distributed feedback hydrogel laser with wavelength tunability is fabricated. The results reveal a 30% increase in slope efficiency in the presence of host molecules. These results, combined with the inherent stimuli‐response of hydrogels, enable new possibilities for affordable and small‐scale photonic devices capable of safely interacting with the environment in, for example, sensing applications.

Cannabidiol-Loaded Nanostructured Lipid Carriers (NLCs) for Dermal Delivery: Enhancement of Photostability, Cell Viability, and Anti-Inflammatory Activity

The aim of this study was to encapsulate cannabidiol (CBD) extract in nanostructured lipid carriers (NLCs) to improve the chemical stability and anti-inflammatory activity of CBD for dermal delivery. CBD-loaded NLCs (CBD-NLCs) were prepared using cetyl palmitate (CP) as a solid lipid and stabilized with Tego® Care 450 (TG450) or poloxamer 188 (P188) by high-pressure homogenization (HPH). The CBD extract was loaded at 1% w/w. Three different oils were employed to produce CBD-NLCs, including Transcutol® P, medium-chain triglycerides (MCT), and oleic acid (OA). CBD-NLCs were successfully prepared with an entrapment efficiency (E.E.) of 100%. All formulations showed particle sizes between 160 and 200 nm with PDIs less than 0.10. The type of surfactant and oil used affected the particle sizes, zeta potential, and crystallinity of the CBD-NLCs. CBD-NLCs stabilized with TG450 showed higher crystallinity after production and storage at 30 °C for 30 days as compared to those with P188. Encapsulation of the CBD extract in NLCs enhanced its chemical stability after exposure to simulated sunlight (1000 kJ/m2) compared to that of the CBD extract in ethanolic solution. The CBD-NLCs prepared from MCT and OA showed slower CBD release compared with that from Transcutol® P, and the kinetic data for release of CBD from CBD-NLCs followed Higuchi's release model with a high coefficient of determination (>0.95). The extent of CBD permeation through Strat-M® depended on the oil type. The cytotoxicity of the CBD extract on HaCaT and HDF cells was reduced by encapsulation in the NLCs. The anti-inflammatory activity of the CBD extract in RAW264.7 cell macrophages was enhanced by encapsulation in CBD-NLCs prepared from MCT and OA.

Engineering Semiconductor Layer Using Halonaphthalene Additives for Organic Opto-Inverter Circuits

Solution-processable organic field-effect transistors (OFETs) are at the forefront of the future of electronic circuits. They have the potential for low-cost, large-scale fabrication on a variety of substrates. However, their application in electronic circuits is challenged by the unforeseen presence of defects leading to lower mobility. In this contribution, the application of a photoactive polymer-based phototransistor in a digital electronic circuit is demonstrated. Initially, a solvent additive engineering strategy is adopted to tune the thin film morphology and reduce morphology-related defects, resulting in improved device performance. The incorporation of 1-bromonaphthalene improves mobility from 0.09 to 0.50 cm2 V–1 s–1 with enhancement in both photoabsorption and photostability. The results are well supported by electrical characterization and photophysical and morphological studies. Thereafter, a unique architecture of an opto-inverter is presented using the OFET. In this work, an optoelectronic logic NOT gate is also fabricated by utilizing a simple resistive load circuit. This circuit is also demonstrated to perform the combined functionality of a logic gate and a transducer. Furthermore, this technique can be easily implemented for minimizing the circuit components and complexity by replacing a photodetector and a NOT gate with a single opto-inverter in applications requiring both.

Photostability Enhancement of Dual-Luminophore Pressure-Sensitive Paint by Adding Antioxidants

Antioxidants were applied to a dual-luminophore pressure-sensitive paint (PSP), and the effects on photodegradation caused by exposure to excitation light were studied. Three types of antioxidants that are commonly used for the photostability enhancement of polymers were added to a dual-luminophore PSP, and degradation rates and pressure/temperature sensitivities were investigated by coupon-based tests. One-hour-long aging tests were performed in a pressure chamber with a continuous excitation light source under dry air and argon atmospheres at 100 kPa and 20 °C. As a result of the aging tests, a singlet oxygen quencher type antioxidant was found to reduce the degradation rate by 91% when compared with the dual-luminophore PSP without antioxidants. This implies that singlet oxygen has a dominant role in the photodegradation mechanism of the dual-luminophore PSP.

The Mechanism of the Photostability Enhancement of Thin-Film Transistors Based on Solution-Processed Oxide Semiconductors Doped with Tetravalent Lanthanides.

The applications of thin-film transistors (TFTs) based on oxide semiconductors are limited due to instability under negative bias illumination stress (NBIS). Here, we report TFTs based on solution-processed In2O3 semiconductors doped with Pr4+ or Tb4+, which can effectively improve the NBIS stability. The differences between the Pr4+-doped In2O3 (Pr:In2O3) and Tb4+-doped In2O3 (Tb:In2O3) are investigated in detail. The undoped In2O3 TFTs with different annealing temperatures exhibit poor NBIS stability with serious turn-on voltage shift (ΔVon). After doping with Pr4+/Tb4+, the TFTs show greatly improved NBIS stability. As the annealing temperature increases, the Pr:In2O3 TFTs have poorer NBIS stability (ΔVon are -3.2, -4.8, and -4.8 V for annealing temperature of 300, 350, and 400 °C, respectively), while the Tb:In2O3 TFTs have better NBIS stability (ΔVon are -3.6, -3.6, and -1.2 V for annealing temperature of 300, 350, and 400 ℃, respectively). Further studies reveal that the improvement of the NBIS stability of the Pr4+/Tb4+:In2O3 TFTs is attributed to the absorption of the illuminated light by the Pr/Tb4fn-O2p6 to Pr/Tb 4fn+1-O2p5 charge transfer (CT) transition and downconversion of the light to nonradiative transition with a relatively short relaxation time compared to the ionization process of the oxygen vacancies. The higher NBIS stability of Tb:In2O3 TFTs compared to Pr:In2O3 TFTs is ascribed to the smaller ion radius of Tb4+ and the lower energy level of Tb 4f7 with a isotropic half-full configuration compared to that of Pr 4f1, which would make it easier for the Tb4+ to absorb the visible light than the Pr4+.

The remarkable enhancement of photo-stability and antioxidant protection of lutein coupled with carbon-dot

Lutein is a carotenoid that is beneficial to human health. However, its low stability and bioavailability have limited its application in the pharmaceutical and food industries. Herein, lutein has been successfully modified with carbon-dots (CDs) via a simple and mild solvent-ultrasonic method at room temperature. The synthesized lutein/CDs composites (LCs) showed 3.4 times higher photostability than the pristine lutein under UV irradiation, and 3.5 times higher than that under visible light, and the retention rate of lutein in the air rose from 3.6 % to 68 % over 25 days. Meanwhile, the antioxidant capacity of lutein has been improved by 6.4 times. Based on the photoluminescence (PL) measurements, a possible mechanism for the enhanced photostability and antioxidant ability of LCs has been proposed. The work provides a simple but effective approach to enhancing the stability and antioxidant capacity of lutein, and is expected to extend its application in food and biomedical fields.

Fluorescence Brightness, Photostability, and Energy Transfer Enhancement of Immobilized Single Molecules in Zero-Mode Waveguide Nanoapertures

Fluorescence Brightness, Photostability, and Energy Transfer Enhancement of Immobilized Single Molecules in Zero-Mode Waveguide Nanoapertures

Palladium nanoparticles decorated MXene for plasmon-enhanced photocatalysis

Two-dimensional MXene nanomaterials have found a wide application range in recent years. Here, Ti3C2 MXene nanosheets exhibiting inherent photothermal activity reveal synergistic plasmon-enhanced photocatalytic properties upon rational surface decoration with palladium nanoparticles (NPs). Pd incorporation induces a 1.7-fold increase in the number of defect sites on the MXene surface. Most importantly, the introduced Pd nanoparticles favour an effective separation and collection of localized surface plasmon resonance (LSPR)-induced hot charge carriers generated at the surface of semi-metallic Ti3C2 NS, further facilitating the generation of hydrogen peroxide (H2O2). The generated H2O2 is sequentially decomposed to hydroxyl radicals via the peroxidase (POD)-like activity of Pd NPs. The Pd@MXene shows approximately 2-fold enhancement of photocatalytic activity and excellent photostability under laser irradiation. Taken together, this study highlights the promise of constructing active and stable MXene-based nanohybrids for highly effective photo-responsive nanomedicine.

Enhancement of Photostability through Side Chain Tuning in Dioxythiophene-Based Conjugated Polymers

Enhancement of Photostability through Side Chain Tuning in Dioxythiophene-Based Conjugated Polymers

Enhancement of fluorescence and photostability of luminescent radicals by quadruple addition of phenyl groups

A photostable luminescent radical with four 4-methoxyphenyl groups showed bright fluorescence in nonpolar solvents. A photostable luminescent radical with four phenyl groups exhibited bright fluorescence also in polar solvents and PMMA film.

Stable and wide-wavelength tunable luminescence of CsPbX3 nanocrystals encapsulated in metal–organic frameworks

The obtained ZJU-28⊃CsPbX3 crystals exhibit giant two-photon action cross-section and photostability enhancement due to the effects of confinement, passivation and separation derived from ZJU-28 frameworks.

Highly Efficient Photoelectrochemical Hydrogen Production Using Nontoxic CuIn1.5Se3 Quantum Dots with ZnS/SiO2 Double Overlayers.

Quantum dots (QDs) are a promising material for photoelectrochemical (PEC) hydrogen (H2) production because of their attractive optical properties including high optical absorption coefficient, band-gap tunability, and potential multiple exciton generation. To date, QDs containing toxic elements such as Cd or Pb have been mainly investigated for PEC H2 production, which cannot be utilized in practice because of the environmental issue. Here, we demonstrate a highly efficient type II heterojunction photoanode of nontoxic CuIn1.5Se3 (CISe) QDs and a mesoporous TiO2 film. In addition, ZnS/SiO2 double overlayers are deposited on the photoanodes to passivate surface defect sites on the CISe QDs, leading to the enhancement of both photocurrent density and photostability. Due to a combination of a wide light absorption range of the CISe QDs and the reduced interfacial charge recombination by the overlayers, a remarkable photocurrent density of 8.5 mA cm-2 (at 0.5 VRHE) is obtained under 1 sun illumination, which is a record for the PEC sulfite oxidation based on nontoxic QD photoanodes.

Enhancement in photostability of betalain dye from basella Alba fruits using zinc oxide nanoparticles

Recently environmental pollution due to industrial effluents is a major concern for researchers, so the development of natural dyes is widely accepted due to their low cost, biodegradability, low toxicity, and non -carcinogenic nature and also replaces existing hazardous chemicals in industries. Many plants and fruit extracts can be used as natural dyes, but their efficiency depends on photostability and photo degradation activity. Herein reported extraction of natural dye fromBasella Alba fruit using different solvents and photo stability was investigated under UV and visible light. To enhance the stability of extracted pure dye, zinc oxide nanoparticles were added and it acts as an excellent photostabilizer that shows better performance over betalain dye. UV visible spectrum of pure dye shows an absorbance peak of 480 nm and functional groups of both dye and zinc oxide were identified by FTIR spectrum. The structure and surface morphology of the synthesized nanoparticle was confirmed by UV–Visible, XRD, SEM-EDAX and TEM analysis. The crystalline structure of zinc oxide was confirmed by XRD and composition was analyzed by EDAX studies. The wurtzite type structure of zinc nanoparticle was confirmed by XRD. The external morphology of prepared zinc oxide nanoparticles is captured using FESEM. The HRTEM and SAED images are confirmed the crystalline structure of the synthesized material. The photostability and photodegradation studies were performed under UV light and at various temperatures like 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. These results clearly show a piece of evidence for the usage of nanoparticles for enhancing photostability of natural dyes.

Photostability enhancement of silica-coated gold nanostars for photoacoustic imaging guided photothermal therapy

Gold nanostars (GNSs) are promising contrast agents for simultaneous photothermal therapy and photoacoustic imaging (PAI) owing to their excellent photothermal conversion efficiency. However, GNSs are easily reshaped under transient high-intensity laser pulses, which can cause a rapid shift in the light absorption peak, resulting in a decrease in both therapeutic and monitoring effects. In this work, we synthesized GNSs without toxic surfactants and coated them with a silica shell to retain their shape, thus maintaining their photostability. The excellent performance of these silica-coated GNSs was verified through both in vitro and in vivo PAI experiments. The silica-coated GNSs exhibited a threefold improvement in photoacoustic stability, as compared with the non-coated GNSs. The proposed silica coating method for GNSs was found to improve the photostability of GNSs, making them efficient, safe, and reliable nanoparticles for PAI.

Substituent screening effect on single-molecule photostability: comparison of three differently substituted porphycenes

Photobleaching of single molecules has been studied using confocal fluorescence microscopy for porphycene, a porphyrin isomer, and its two derivatives. Fourfold substitution of porphycene with bulky tert-butyl groups leads to the enhancement of photostability, even though the spectral, photophysical, and redox parameters remain similar. We attribute this effect to the increase of the efficiency of physical quenching of the chromophore triplet state by oxygen, compared with the yield of chemical reaction that leads to photobleaching. Analysis of the observed photon fluxes from single emitters embedded in a polymer film shows that the experiment based on fluorescence is biased towards detection of molecules which have oxygen—the triplet quencher—in their vicinity. The distribution of the measured photodegradation quantum yields is very heterogeneous, suggesting that physical and chemical quenching rates exhibit different distance and orientation dependences.

Long‐Range Exciton Migration in Coassemblies: Achieving High Photostability without Disrupting the Electron Donation of Fluorene Oligomers

AbstractIn this work, photostable coassemblies from a nonphotostable fluorene oligomer (the energy donor) and a photostable oligomer (the energy acceptor) are fabricated. Long‐range exciton migration over a net distance of about 370 energy‐donor molecules to energy acceptors is demonstrated in such coassemblies. The fast and long energy migration allows harvesting of the excitation energy of energy donors by embedding a small number of energy acceptors for photostability enhancement. Importantly, embedding a small number of energy acceptors in coassemblies causes a negligible negative influence on the electron donation of energy donors that are desired in practical applications. The advantages of the coassemblies fabricated, that is, high photostability without disrupting the electron donation of energy donors, are well illustrated in fluorescence detection of trace explosives where prolonged working life and improved detection capacity are achieved.

Long-Range Exciton Migration in Coassemblies: Achieving High Photostability without Disrupting the Electron Donation of Fluorene Oligomers.

In this work, photostable coassemblies from a nonphotostable fluorene oligomer (the energy donor) and a photostable oligomer (the energy acceptor) are fabricated. Long-range exciton migration over a net distance of about 370 energy-donor molecules to energy acceptors is demonstrated in such coassemblies. The fast and long energy migration allows harvesting of the excitation energy of energy donors by embedding a small number of energy acceptors for photostability enhancement. Importantly, embedding a small number of energy acceptors in coassemblies causes a negligible negative influence on the electron donation of energy donors that are desired in practical applications. The advantages of the coassemblies fabricated, that is, high photostability without disrupting the electron donation of energy donors, are well illustrated in fluorescence detection of trace explosives where prolonged working life and improved detection capacity are achieved.