Improved Light Stability Research Articles

Fish freshness monitoring based on bilayer cellulose acetate/polyvinylidene fluoride membranes containing ZIF-8 loaded curcumin

This study presented a dual-layer freshness indicator film produced through electrospinning, combining cellulose acetate and polyvinylidene fluoride with zeolitic imidazolate framework-8 (ZIF-8) loaded with curcumin as the indicator. Our findings demonstrated that ZIF-8 effectively preserved its metal-organic framework structure during curcumin loading, ensuring the inherent color-changing ability of curcumin. The resulting colorimetric film exhibited altered tensile properties and increased water vapor permeability. Improved light stability and storage performance were observed. Compared to single-layer films, the dual-layer structure improved the hydrophilicity and stability of the indicator film. Importantly, the introduced indicator label efficiently captured the dynamic changes of TVB-N during freshness monitoring, providing comprehensive visual information for assessing fish freshness. The synergistic properties of ZIF-8, curcumin, and the dual-layer film structure contributed to an advanced freshness indicator system, providing a multifunctional and effective approach for real-time freshness assessment of fish freshness.

Formulation of Polymeric Micelles to Increase the Solubility and Photostability of Caffeic Acid.

Caffeic acid (CA), a hydrophobic polyphenol with various pharmacological activities, exhibits a low aqueous solubility and sensitivity to light. In order to improve its chemical properties and overcome the limits in its application, the compound was loaded in P123 micelles (MCs) prepared using two polymer concentrations (10 and 20% w/w, MC10 and MC20). The micelles were characterised in terms of the size distribution, zeta potential, drug encapsulation efficiency, rheology, and cumulative drug release. Micellar formulations exhibited sizes in the range of 11.70 and 17.70 nm and a good polydispersion, indicating the formation of relatively small-sized micelles, which is favourable for drug delivery applications. Additionally, the stability and antioxidant profiles of the free CA and the CA loaded in micelles were studied. The results obtained on the free CA showed the formation of photodegradation products endowed with higher DPPH scavenging activity with respect to the pure compound. Instead, it was found that the incorporation of CA into the micelles significantly increased its solubility and decreased the photodegradation rate. Overall, the results indicate the successful formation of P123 micelles loaded with CA, with promising characteristics such as a small size, good encapsulation efficiency, sustained release profile, and improved light stability. These findings suggest the potentiality of these micelles as a delivery system for CA, thus enhancing its bioavailability.

Kinetics Controlled Perovskite Crystallization for High Performance Solar Cells.

The power conversion efficiencies (PCEs) of perovskite solar cells have recently developed rapidly compared to crystalline silicon solar cells. To have an effective way to control the crystallization of perovskite thin films is the key for achieving good device performance. However, a paradox in perovskite crystallization is from the mismatch between nucleation and Oswald ripening. Usually, the large numbers of nucleation sites tend to weak Oswald ripening. Here, we proposed a new mechanism to promote the formation of nucleation sites by reducing surface energy from 44.9 mN/m to 36.1 mN/m, to spontaneously accelerate the later Oswald ripening process by improving the grain solubility through the elastic modulus regulation. The ripening rate is increased from 2.37 Åm ⋅ s-1 to 4.61 Åm ⋅ s-1 during annealing. Finally, the solar cells derived from the optimized films showed significantly improved PCE from 23.14 % to 25.32 %. The long-term stability tests show excellent thermal stability (the optimized device without encapsulation maintaining 82 % of its initial PCE after 800 h aging at 85 °C) and an improved light stability under illumination. This work provides a new method, the elastic modulus regulation, to enhance the ripening process.

Kinetics Controlled Perovskite Crystallization for High Performance Solar Cells

AbstractThe power conversion efficiencies (PCEs) of perovskite solar cells have recently developed rapidly compared to crystalline silicon solar cells. To have an effective way to control the crystallization of perovskite thin films is the key for achieving good device performance. However, a paradox in perovskite crystallization is from the mismatch between nucleation and Oswald ripening. Usually, the large numbers of nucleation sites tend to weak Oswald ripening. Here, we proposed a new mechanism to promote the formation of nucleation sites by reducing surface energy from 44.9 mN/m to 36.1 mN/m, to spontaneously accelerate the later Oswald ripening process by improving the grain solubility through the elastic modulus regulation. The ripening rate is increased from 2.37 Åm ⋅ s−1 to 4.61 Åm ⋅ s−1 during annealing. Finally, the solar cells derived from the optimized films showed significantly improved PCE from 23.14 % to 25.32 %. The long‐term stability tests show excellent thermal stability (the optimized device without encapsulation maintaining 82 % of its initial PCE after 800 h aging at 85 °C) and an improved light stability under illumination. This work provides a new method, the elastic modulus regulation, to enhance the ripening process.

Perovskite Solar Cells with Extremely High 24.63% Efficiency through Design of Double Electron Transport Layers and Double Luminescent Converter Layers

AbstractIntroduction of fluorescent down‐conversion layer inside perovskite solar cells (PSCs) can highly improve the ultraviolet response of the devices and the light stability. However, such a device is usually confronted with the problem of inter‐diffusion with the perovskite absorber layer, which severely limits its further development. To address this problem, herein, this work employs an interfacial dual electron transport layers (ETLs) strategy, sandwiching Cd‐CsPbCl3:Mn2+ luminescent quantum dots within gap of the ETLs, which not only reduces the interface energy level offset, but also improves the nucleation and crystallization kinetics of perovskite films and prevents their diffusion to the perovskite absorber layer. As a result, the efficient synergy effect effectively elevates both the open‐circuit voltage and fill factor of the PSCs, reaching maximum values of 1.181 V and 81.14%, respectively, finally delivering progressively increased device power conversion efficiency (PCE) of 24.32% with significantly improved light stability. To further improve the ultraviolet response, this work further adopts the strategy of dual fluorescent conversion layers inside and outside the PSCs, and finally obtains PCE of 24.63%, which is the best for various luminescent conversion cells. This work opens a new door for the development of efficient and stable photoluminescence conversion PSCs.

Halogenated Hole‐Transport Molecules with Enhanced Isotropic Coordination Capability Enable Improved Interface and Light Stability of Perovskite Solar Cells

AbstractInterfacial defects are one of the main origins of the hysteresis effect and limit the efficiency and light stability of perovskite solar cells (PSCs). Herein, the authors propose to grant the hole‐transport materials’ (HTMs) improved isotropic coordination and defect passivation through simple halogenation, enabling a robust perovskite/hole‐transport layer interface while avoiding the use of an external passivation layer. First‐principles simulations and experimental results show that the halogenated HTMs offer more isotropic coordination sites for Pb2+ ions than the halogen‐free ones, thus providing the enhanced passivating ability of defects regardless of their molecular orientation at the surface of perovskite films. Consequently, the PSCs based on the chlorinated spiro[fluorene‐9,9′‐xanthene]‐based HTM show suppressed nonradiative recombination, delivering a remarkable open‐circuit voltage (VOC) enhancement (from 1.07 to 1.14 V) and a minimal hysteresis index of as low as 0.07%. The corresponding cells also show much improved light stability, retaining 81% of the initial efficiency after 1000 h of continuous illumination at the maximum power point. This work demonstrates that a solid isotropic coordination capability of HTMs with Pb2+ is critical to forming a robust interface and improving the PSCs’ light stability.

Pre-annealing treatment for high-efficiency perovskite solar cells via sequential deposition

<h2>Summary</h2> Grain boundaries (GBs) have been shown to initiate metal halide perovskite degradation under light, moisture, and/or heat stresses due to the existence of various defects, making them extremely vulnerable in perovskite solar cells (PSCs). Although various post-treatments have been proven to be effective in repairing GBs, preventing the degradation from perovskite GBs remains an extremely difficult challenge. We report here a generic pre-annealing treatment for reconstructing sequentially deposited perovskite crystallites and GBs. With this strategy, robust GBs are created upon defect suppression with preferred oriented large perovskite grains. As a result, the resultant n-i-p-structured PSCs deliver an impressive power conversion efficiency of nearly 25% and an extremely high fill factor of 85.5%. The unencapsulated cells maintain 81% of their initial efficiencies after 1,000 h of continuous operation at maximum power point at about 55°C in an inert atmosphere, showing greatly improved light stability.

Efficient Tin (II) Fluoride‐Free Formamidinium Tin Triiodide Perovskite Solar Cells via Composition and Additive Engineering

Tin halide perovskite solar cells (TPSCs) have attracted extensive attention because of their low toxicity and high theoretical efficiency. However, rapid crystallization, rich defects, and easy oxidation of tin‐based perovskite films seriously restrict solar cell performance. Herein, a composition and additive engineering solution by removing commonly used tin fluoride additive from formamidinium tin triiodide perovskite precursors and replacing it with excess tin (II) iodide and ethylenediamine dihydroiodide (EDAI2) is adopted. The presence of EDAI2 and excess SnI2 and the absence of SnF2 enable tin‐based perovskite films with greatly improved morphology, enhanced crystalline quality, boosted optical properties, and prolonged carrier lifetime. Therefore, the SnF2‐free non‐stoichiometric TPSCs employing the EDAI2 additive and excess SnI2 have increased built‐in potential, lowered dark currents, and reduced carrier recombination. The resulting SnF2‐free and SnI2‐rich TPSCs with EDAI2 addition realize a steady‐state efficiency of 10.0%, which is one of the highest power conversion efficiencies among the SnF2‐free TPSCs, along with considerably improved light stability. This work highlights the crucial roles of additives in TPSCs and provides an effective strategy to fabricate efficient and stable low‐toxic lead‐free perovskite solar cells.

Cathode Interface Layer Based on Organosilica Nanodots for Efficient and Stable Inverted Organic Solar Cells

The interface layer greatly affects the performance of organic solar cells (OSCs). In this paper, we selected an amino-containing silane molecule (AEEA) and four fluorescein molecules with different functional groups to prepare a series of cathode interface materials based on organosilica nanodots (OSiNDs) by one-step hydrothermal synthesis, in order to research the impact of functional groups on the performance of OSC devices. The good film crystallinity and carrier mobility without high-temperature annealing endowed the OSCs with high Voc and Jsc, and the best efficiency of 15.91% was reached with the OSi-ErB cathode interlayer. Moreover, compared with ZnO devices, OSiND-based devices showed highly improved light stability after UV irradiation.

Strain Modulation for Light‐Stable n–i–p Perovskite/Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells are promising to penetrate photovoltaic market. However, the wide-bandgap perovskite absorbers used in top-cell often suffer severe phase segregation under illumination, which restricts the operation lifetime of tandem solar cells. Here, a strain modulation strategy to fabricate light-stable perovskite/silicon tandem solar cells is reported. By employing adenosine triphosphate, the residual tensile strain in the wide-bandgap perovskite absorber is successfully converted to compressive strain, which mitigates light-induced ion migration and phase segregation. Based on the wide-bandgap perovskite with compressive strain, single-junction solar cells with the n-i-p layout yield a power conversion efficiency (PCE) of 20.53% with the smallest voltage deficits of 440mV. These cells also maintain 83.60% of initial PCE after 2500 h operation at the maximum power point. Finally, these top cells are integrated with silicon bottom cells in a monolithic tandem device, which achieves a PCE of 26.95% and improved light stability at open-circuit.

Coherent interlayers expand perovskite opportunities

<h2>Summary</h2> Interfacial modification contributes to improving the performance of PSCs. Recently in <i>Nature</i>, Min and coworkers first revealed FASnCl_x phase as a coherent interlayer between the perovskite and SnO₂, leading to the reduced interfacial charge recombination loss and contact resistance. A certified PCE of 25.5% with improved light stability was obtained.

Excess charge-carrier induced instability of hybrid perovskites

Identifying the origin of intrinsic instability for organic–inorganic halide perovskites (OIHPs) is crucial for their application in electronic devices, including solar cells, photodetectors, radiation detectors, and light-emitting diodes, as their efficiencies or sensitivities have already been demonstrated to be competitive with commercial available devices. Here we show that free charges in OIHPs, whether generated by incident light or by current-injection from electrodes, can reduce their stability, while efficient charge extraction effectively stabilizes the perovskite materials. The excess of both holes and electrons reduce the activation energy for ion migration within OIHPs, accelerating the degradation of OIHPs, while the excess holes and electrons facilitate the migration of cations or anions, respectively. OIHP solar cells capable of efficient charge-carrier extraction show improved light stability under regular operation conditions compared to an open-circuit condition where the photo-generated charges are confined in the perovskite layers.

RF sputtered CdS films as independent or buffered electron transport layer for efficient planar perovskite solar cell

Metal sulfide has the potential to take the place of high temperature sintered TiO2 as electron transportation layer for perovskite solar cell (PSC) with improved light stability and suppressed hysteresis. In this work, CdS films were used as independent or buffered electron transport layer for planar perovskite solar cell by a low-temperature RF sputtering method for the first time. The effects of surface roughness and optical absorption of CdS films on the photovoltaic performance of PSCs were discussed. The PSC with sputtered CdS film shows a higher open-circuit voltage (Voc) and efficiency of 13.17% than high temperature sintered TiO2 ETL (12.71%). Moreover, a RF sputtered CdS buffer layer between TiO2 and perovskite could tune the conduction band edge of TiO2 and perovskite and passivating the surface defects. Time resolved photoluminescence results indicate the RF sputtered CdS film buffer layer could accelerate charge transportation and a higher conversion efficiency over 16% has thus been achieved, with enhanced air stability and minimized hysteresis. These findings offer new research directions for low-temperature sputtered metal sulfide film as a promising electron transport material for stable and high efficient planar perovskite solar cell.

Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

Reduction of C,O-chelated organotin(IV) dichlorides and dihydrides leading to protected polystannanes

A series of aryloxy organotin compounds Ph3Sn(CH2)3OC6H4R (5: R = H; 6: R = Ph; 7: R = OCH3, 8: R = CF3), Ph2ClSn(CH2)3OC6H4R (9: R = H; 10: R = Ph) and PhCl2Sn(CH2)3OC6H4R (12: R = H; 13: R = Ph) have been synthesized and characterised by NMR (1H, 13C, 119Sn) spectroscopy. X-ray structure determinations of 9, 10, 12 and 13 reveal a distorted trigonal bipyramidal geometry at Sn with Cl trans to the datively bonded O whereas 8 possesses tetrahedral geometry and a Sn⋯O dative interaction is absent. Triorganotin hydrides Ph2HSn(CH2)3OC6H4R (14: R = H; 15: R = Ph) and diorganotin dihydrides PhH2Sn(CH2)3OC6H4R (16: R = H; 17: R = Ph) were prepared by reduction of the corresponding dihalides with LiAlH4. Catalytic dehydrocoupling of dihydrides 16 or 17 with a late transition metal catalyst afforded asymmetrical hypercoordinated polystannanes [PhSn(CH2)3OC6H4R]n (18: R = H; 19: R = Ph) with relatively high molecular weights (Mw = 1.3 × 104 – 2.5 × 105 Da) and narrow polydispersities (PDI's = 1.3–3.3). NMR and UV–Vis spectroscopy studies indicate that the new polymers display dramatically improved light stability, but remain sensitive to moisture.

Effect of Nitrogen Sources on Production and Photostability of Monascus Pigments in Liquid Fermentation

The effect of different nitrogen sources on the yield, distribution and photostability of monascus pigments was detected in liquid fermentation. Compared to the control, glutamic and 6-furturylaminopurine could increase the production of pigments from 4185 to 4303 and 4349 U g−1 for different mechanism. More important, 6-furturylaminopurine could increase the extracellular pigments from 697 to 1404 U g−1. and increased the hue of fermentation broth from 0.887 to 1.072. The light stability of extra and intracellular red pigments could be improved by adding different nitrogen. The half- life of derivatives from Tryptophan and 6-furturylaminopurine increased from 1h (control) to 4 and 3h. It was concluded that different nitrogen sources could affected the pigments production, the hue of fermentation liquid, and improved light stability of monascus pigment. It was very usefull for increasing the production and improving the light stability of monascus pigments.

Uniform Silica Coated Fluorescent Nanoparticles: Synthetic Method, Improved Light Stability and Application to Visualize Lymph Network Tracer

BackgroundThe sentinel lymph node biopsy (SLNB) was developed as a new modality in the surgical diagnosis of lymph node metastases. Dye and radioisotope are major tracers for the detection of sentinel lymph nodes (SLN). Dye tends to excessively infiltrate into the interstitium due to their small size (less than several nanometers), resulting in difficulties in maintaining clear surgical fields. Radioisotopes are available in limited number of hospitals. Fluorescent nanoparticles are good candidates for SLN tracer to solve these problems, as we can choose suitable particle size and fluorescence wavelength of near-infrared. However, the use of nanoparticles faces safety issues, and many attempts have been performed by giving insulating coats on nanoparticles. In addition, the preparation of the uniform insulating layer is important to decrease variations in the quality as an SLN tracer.Methodology/Principal FindingsWe herein succeeded in coating fluorescent polystyrene nanoparticles of 40 nm with uniform silica layer of 13 nm by the modified Stöber method. The light stability of silica coated nanoparticles was 1.3-fold greater than noncoated nanoparticles. The popliteal lymph node could be visualized by the silica coated nanoparticles with injection in the rat feet.Conclusions/SignificanceThe silica coated nanoparticles in lymph nodes could be observed by transmission electron microscope, suggesting that our silica coating method is useful as a SLN tracer with highly precise distribution of nanoparticles in histological evaluation. We also demonstrated for the first time that a prolonged enhancement of SLN is caused by the phagocytosis of fluorescent nanoparticles by both macrophages and dendritic cells.

Effects on the Flavor and Oxidative Stability of Stripped Soybean and Sunflower Oils with Added Pure Tocopherols

Effects of tocopherols on the oxidative stability of stripped vegetable oils were studied by adding pure tocopherols--alpha, beta, gamma, and delta--in their naturally occurring proportions in soybean and sunflower oils to the triacylglycerols (TAG) of soybean and sunflower oils. Soybean and sunflower oils were purified by stripping all minor constituents, leaving the triacylglycerols. Pure tocopherols in the proportion typical of sunflower oil--high alpha, low gamma, and low delta--were added to purified sunflower oil and to purified soybean oil. Pure tocopherols in the proportion typical of soybean oil--low alpha, high gamma, and high delta--were added to the purified oils. Oils were subjected to accelerated autoxidation using oven storage at 60 degrees C in the dark and accelerated photooxidation at 7500 lx light intensity at 30 degrees C. Oxidation levels of aged oils were measured by the formation of both peroxides and volatile compounds and by flavor analysis. Results from substituting the tocopherol profile from one oil type to another varied on the basis of whether they were oxidized in the dark or in the light. For example, during autoxidation in the dark, soybean oil with the typical soybean tocopherol profile had the lowest levels of peroxides and total volatile compounds, whereas sunflower oil with the sunflower tocopherol profile had the highest levels. In flavor analyses of the same oils, sunflower oil with the soybean tocopherol profile was the most stable. Soybean oil with the profile of sunflower tocopherols was the least stable in dark oxidation. In contrast to the data from autoxidation in the dark, addition of tocopherols typical of sunflower oil significantly improved light stability of both oil types compared to the addition of soybean tocopherols to sunflower oil. The tocopherol profile typical of soybean oil was significantly more effective in inhibiting autoxidation in the dark; however, the tocopherol profile typical of sunflower oil inhibited light oxidation significantly more than the soybean tocopherol profile.

Development of New Photo-thermographic Materials with Improved Light Stability of the Image

Development of New Photo-thermographic Materials with Improved Light Stability of the Image

Improved light stability of colored SiO2 coatings containing organic and metalorganic dye molecules

Organic and metalorganic dyes have been incorporated into SiO2 coatings using the sol-gel method. It is found that the coatings prepared from sol-gel starting solutions, which were subjected to a ball milling process, have improved light stability. Using optical absorption, atomic force microscopy and microluminescence measurements, it is found that the ball milling process of the starting solutions not only produces better dye dispersion, but there are also some indications that it produces a structure with fewer and smaller pores. These results are in agreement with previous studies, which indicate that the photostability of dyes in metal oxide matrices can be improved when the dye is better dispersed and trapped in more rigid cages.