Intense Light Irradiation Research Articles

Non-vacuum room temperature-processed sintering method of molybdenum pattern by intense pulsed light irradiation for high-performance electronic devices

In this study, the molybdenum (Mo) pattern was realized via intense pulsed light (IPL) irradiation process under ambient condition, without vacuum deposition process. The screen printing method was applied to realize a certain pattern using conductive ink composed of Mo nanoparticles. This printed Mo pattern showed low electrical conductivity due to oxide film on the nanoparticles surface. To improve this drawback, the IPL irradiation process was optimized for sintering of Mo pattern, therefore the remarkable electrical conductivity (35 μΩ·cm) was observed after IPL irradiation process. To investigate the microstructure and other reaction effects of Mo pattern, the various analysis was conducted such as scanning electron microscope, X-ray diffraction, focused ion beam analysis. This printed Mo pattern was applied for the source and drain (S/D) electrode of indium gallium zinc oxide (IGZO) based thin film transistor (bottom gate; TFT). The interfacial microstructure between Mo pattern and IGZO layer was investigated by transmittance electron microscope analysis. Consequently, the TFT with IPL-sintered Mo (S/D) pattern showed a noteworthy saturation mobility of 13.5 cm2·(V·s)−1.

REZULTATE PRELIMINARE ALE ANALIZEI PRINCIPALILOR FACTORI DE MICROCLIMAT ÎNTR-UN MODUL DE FERMĂ URBANĂ

As in the case of humans, in the case of plants grown in protected areas, specific microclimate conditions must be ensured for their optimal development during the growing season. The development of plants is the result of their own genetic characteristics, but this is influenced by the microclimate conditions in the environment in which they grow. In the growing areas, the specific microclimate conditions must be strictly monitored. On the other hand, in the context of climate change and urbanization, there has been a need to develop specialized modules for vegetable production. Growing vegetables on urban farms is an increasingly used concept internationally. In this sense, a team of researchers from the INMA and HORTING Institutes in Bucharest - Romania has developed a collaborative project, which aims to investigate the main microclimate parameters such as temperature, relative humidity, CO2 concentration and light radiation intensity inside a prototype urban farm for research, in which green vegetables and microplants can be grown. Due to the complexity of the phenomena that take place in the closed spaces of culture, the amount of information necessary for the complete quantification of the variables of microclimate factors depends both on the intensity of the thermo-physical processes and on the accuracy of the measuring instruments used. This paper presents the preliminary results of the investigation of the main microclimate parameters within the experimental module. This module is a good laboratory tool that could be used in a series of research on the influence of light radiation on certain characteristics of microplants or vegetable seedlings. Analyzing the influence of the light radiation that reaches the plants, it can be seen that they have a great influence on the way they grow.

Investigation of the impact of supplemental reflective films to improve micro-light climate within tomato plant canopy in solar greenhouses.

The non-uniform growth and development of crops within Chinese Solar Greenhouses (CSG) is directly related to the micro-light climate within canopy. In practice, reflective films are used to improve micro-light climate within plant canopy by homogenizing light distribution and so increasing total plant light interception. However, as to our knowledge, the contributions to light distribution within canopy have not been investigated for passive reflector like reflective films. Field experiments dealing with light conditions and growth behavior over time, are complicated to carry out, time-consuming and hard to control, while however, accurate measurements of how reflective films influence the micro-light climate of canopy are an essential step to improve the growth conditions for any crop. Here, we propose a supplementary light strategy using reflective films to improve light distribution within plant canopy. Based on the example of CSG, a 3D greenhouse model including a detailed 3D tomato canopy structure was constructed to simulate the influence of supplementary reflective films to improve micro-light climate. Comparison of measured solar radiation intensity with predicted model data demonstrated that the model could precisely predict light radiation intensity over time with different time points and positions in the greenhouse. A series of reflective film configurations were investigated based on features analysis of light distribution in the tomato canopy on sunny days using the proposed model. The reflective film configuration scheme with the highest impact significantly improved the evenness of horizontal and vertical light distribution in tomato canopy. The strategy provided here can be used to configure reflective films that will enhance light conditions in CSG, which can be applied and extended in different scenarios.

Photo-enhanced dry reforming of methane over Pt-Au/P25 composite catalyst by coupling plasmonic effect

Driving the dry reforming of methane (DRM) reaction via integrating the photo and thermal catalysis is a promising strategy to release the greenhouse effect caused by greenhouse gases (CH4/CO2). However, existing photo-thermal catalysts have limited response range to light (ultraviolet region), and broadening light response region to reaching high-performance is quite critical for DRM reaction. Here, the Pt-Au/P25 photo-thermal catalyst was proposed. The catalyst showed obvious enhancement of response range that widened to visible light region. The catalytic performance of catalyst was improved by the SPR effect. The structure–activity relationship was determined by XRD, XPS, Raman, UV–vis and PL spectra. Pt-Au/P25 catalytic performance was evaluated in different light irradiation intensity and reaction temperature. It was found that light irradiation greatly increased the catalytic performance of DRM reaction. The formation rate of H₂ was 85.38 mmol·gcat−1·h−1 and 201.92 mmol·gcat−1·h−1 for CO at 500 °C under 4.6 W·cm−2 light irradiation intensity, which were 3.09 times for H2 and 2.08 times for CO compared with dark conditions. Moreover, The DRM reaction mechanism was investigated by in situ DRIFTS test. It was found that among the intermediate species (CHx, HCOO*, H* and so on), HCOO* was critical species for the DRM reaction to proceed. During the photo-thermal DRM reaction process, activation/dissociation of CH4 and CO2 and formation of H2 steps were strengthened due to photoelectric and SPR effect by light irradiation.

Design of carbonized melamine sponge@MOFs composites bearing diverse acid-base properties for boosting thermal and solar-driven CO2 cycloaddition

Integrating dual Lewis acid and base as well as rational hierarchical pore structure in one catalyst is favorable to significantly boost the CO2 cycloaddition reaction at mild conditions. In this regard, carbonized melamine sponge (CMS) featuring a highly porous network, rich nitrogen doping and excellent photothermal capability is employed as the ideal host for the construction of CMS@MOFs (namely, MIL-88-NH2 and ZIF-8-NH2) composites with diverse acid-base properties. Results show that all the obtained composites exhibited a satisfactory CO2 adsorbing capacity (33–54 cm3/g) and delivered a remarkable yield of target cyclic carbonate at either mild thermal conditions (0.1 MPa CO2 and 80 oC) or under light irradiation (light intensity: ~350 mW/cm2) at room temperature. Even with diluted CO2 (15 vol. % CO2), high yields of 80–82 % are achievable. Moreover, the used catalysts can be easily recycled from reaction systems, leading to a good recyclability.

Development of plasmonic thin-layer chromatography for size-selective and optical-property-dependent separation of quantum dots

Nano-objects, such as quantum dots (QDs), are essential units for the construction of functional materials and devices in current technologies. The establishment of a versatile scheme to sort desired components from a crude product is crucial for bringing out the full potential of the original materials. However, it is still challenging to separate QDs with the same composition on the basis of size and to sort QDs with the same size but different optical properties. Here, we demonstrate such sorting for the first time by combining plasmonic optical trapping with thin-layer chromatography (TLC), which is a widely used tool. LED photoexcitation of the localized surface plasmon resonance of Au nanoparticles immobilized on a TLC plate affected the distance QDs traveled depending on the wavelength and intensity of irradiated light, which led to clear separation according to the size and/or optical properties of the QDs. Since optical property-based separation cannot be achieved by conventional chromatography, in which the interactions between stationary phases of chromatographs and QDs are simply based on differences in the size or surface functionality of the QDs, the present strategy will be a key solution for the establishment of a versatile scheme for sorting nano-objects.

Electron-Rich EDOT Linkers in Tetracationic bis-Triarylborane Chromophores: Influence on Water Stability, Biomacromolecule Sensing, and Photoinduced Cytotoxicity.

Three novel tetracationic bis‐triarylboranes with 3,4‐ethylenedioxythiophene (EDOT) linkers, and their neutral precursors, showed significant red‐shifted absorption and emission compared to their thiophene‐containing analogues, with one of the EDOT‐derivatives emitting in the NIR region. Only the EDOT‐linked trixylylborane tetracation was stable in aqueous solution, indicating that direct attachment of a thiophene or even 3‐methylthiophene to the boron atom is insufficient to provide hydrolytic stability in aqueous solution. Further comparative analysis of the EDOT‐linked trixylylborane tetracation and its bis‐thiophene analogue revealed efficient photo‐induced singlet oxygen production, with the consequent biological implications. Thus, both analogues bind strongly to ds‐DNA and BSA, very efficiently enter living human cells, accumulate in several different cytoplasmic organelles with no toxic effect but, under intense visible light irradiation, they exhibit almost instantaneous and very strong cytotoxic effects, presumably attributed to singlet oxygen production. Thus, both compounds are intriguing theranostic agents, whose intracellular and probably intra‐tissue location can be monitored by strong fluorescence, allowing switching on of the strong bioactivity by well‐focused visible light.

Organic photoconductive film–stacked active pixel sensor pixel circuits using indium–tin–zinc-oxide thin-film transistors

In this study, we describe the signal readout capabilities of indium–tin–zinc-oxide (ITZO) thin-film transistor (TFT)-based active pixel sensor (APS) pixel circuits combined with organic photoconductive films (OPFs). A pixel circuit was fabricated with a size of 50 μm containing three ITZO TFTs having a channel length of 2 μm and a blue-sensitive OPF possessing excellent properties with an external quantum efficiency of ∼59% and a dark current density of <100 pA cm−2. Signal readout operation of the pixel circuits in accordance with irradiated light intensity was demonstrated, and sufficient response speeds within the line selection period, assuming a pixel number of 320 × 240 (QVGA) at 60 frames per second (∼69.4 μs), was also confirmed by fabricating pixel line arrays comprising 320 and 240 pixels. Our findings show that the miniaturized ITZO TFTs have potential for use in high-pixel-density TFT-based APS image sensors with improved imaging quality.

18.55% Efficiency Polymer Solar Cells Based on a Small Molecule Acceptor with Alkylthienyl Outer Side Chains and a Low-Cost Polymer Donor PTQ10

18.55% Efficiency Polymer Solar Cells Based on a Small Molecule Acceptor with Alkylthienyl Outer Side Chains and a Low-Cost Polymer Donor PTQ10

Light as a Tool in Organic Photocatalysis: Multi‐Photon Excitation and Chromoselective Reactions

AbstractOver the past decades, photoredox catalysis has developed to the big mature field of chemistry. Especially in the field of organic synthesis, more and more sustainable alternatives to conventional synthesis are being developed. Nonetheless, most research activities are focused on the development of new synthetic pathways, utilizing photons as a source of energy for breaking and building of new chemical bonds. We discuss here cases, where selection of the irradiation mode, light intensity (one‐, two‐ photons) or wavelength (UV, blue, green) has a crucial role on the outcome of the photocatalytic event. Thus, control over irradiation conditions influence the reaction mechanism and offers an access to highly reactive species that are otherwise hardly available. This allows for the unique chemical events to happen, such as deep reduction reactions. The principles of these concepts and their applications are reviewed for both homogeneous and heterogeneous photocatalysts.

Bioinspired Photo-Responsive Liquid Gating Membrane.

Stomata in the plant leaves are channels for gas exchange between the plants and the atmosphere. The gas exchange rate can be regulated by adjusting the opening and closing of stoma under the external stimuli, which plays a vital role in plant survival. Under visible light irradiation, the stomata open for gas exchange with the surroundings, while under intense UV light irradiation, the stomata close to prevent the moisture loss of plants from excessive transpiration. Inspired by this stomatal self-protection behavior, we have constructed a bioinspired photo-responsive liquid gating membrane (BPRLGM) through infusing the photo-responsive gating liquid obtained by dissolving the azobenzene-based photo-responsive surfactant molecules (AzoC8F15) in N,N-Dimethylacetamide (DMAC) into nylon porous substrate, which can reversibly switch the open/closed states under different photo-stimuli. Theoretical analysis and experimental data have demonstrated that the reversible photoisomerization of azobenzene-based surfactant molecules induces a change in surface tension of the photo-responsive gating liquid, which eventually results in the reversible variation of substantial critical pressure for gas through BPRLGM under alternating UV (PCritical (off)) and visible (PCritical (on)) light irradiations. Therefore, driven by a pressure difference ΔP between PCritical (on) and PCritical (off), the reversible switches on the open/closed states of this photo-responsive liquid gating membrane can be realized under photo-stimuli. This bioinspired membrane with switchable open/closed liquid gating performance under photo-stimuli has the opportunity to be used in the precise and contactless control of microfluidics.

Promoted solar-driven dry reforming of methane with Pt/mesoporous-TiO2 photo-thermal synergistic catalyst: Performance and mechanism study

Coupling the concept of photo-thermal catalysis is a promising strategy for solar driven DRM reaction. However, highly efficient photo-thermal catalyst and its catalytic reaction mechanism are still barren. Therefore, a highly efficient Pt/mesoporous TiO2 photo-thermal catalyst is reported in this work, and reaction mechanism is investigated through XRD, XPS, Raman, UV–vis–nir, PL and in situ DRIFTS. It is found that Pt active sites and semiconductor TiO2 could work together with SPR and photoelectric effects to enhance adsorption and activation of CH4 and CO2, as well as the conversions of intermediate products (CHx, COO–, –OH etc.). Besides, the formation rates of CO and H2 are 281.0 and 178.6 mmol·gcat−1·h−1 respectively under 500 °C and 3.1 W·m−2 light irradiation intensity, which are 1.58 and 1.74 times higher than those under dark conditions. The activities of the prepared Pt/mesoporous-TiO2 catalyst performs better than recently published reports, showing great potential in photo-thermal chemical conversions.

Effects of the oxygen mass fraction on the wave propagation modes in a kerosene-fueled rotating detonation combustor

In the present study, an experimental model of liquid kerosene-fueled rotating detonation combustor (RDC) was established. The propagation modes of detonation waves were investigated, and the effects of the oxygen mass fraction and the equivalence ratio were analyzed. Dynamic pressure transducers and a high-speed camera were used to capture the pressure signals and combustion field images, respectively. When the oxygen mass fraction was less than 40.5%, there was only one dominant wave frequency in the combustor. However, as the oxygen mass fraction increased to more than 43.6%, a higher dominant wave frequency was generated. To determine the wave propagation modes, high-speed photographic images were transformed and merged chronologically to visualize the trajectory of the detonation waves. Synchronous measurement of the dynamic pressures and high-speed images showed that the reaction zone is coupled to the leading wave front. The two dominant frequencies correspond to the two main modes of the detonation wave, namely the two counter-rotating wave and four counter-rotating wave modes, respectively. It appeared that the wave propagation mode transition was a common phenomenon in the present study, while the wave mode alternated between the single-wave, two counter-rotating wave, and four counter-rotating wave modes. An increase in the number of waves led to a drop in the wave peak pressure, increasing the average light radiation intensity in the combustor. As the equivalence ratio increased, the proportion of the four counter-rotating wave modes decreased. This study also reveals that under the condition of low total mass flux supply, the detonation wave is more probably to exhibit counter-rotating mode.

Microwave assisted facile fabrication of dual Z-scheme g-C3N4/ZnFe2O4/Bi2S3 photocatalyst for peroxymonosulphate mediated degradation of 2,4,6-Trichlorophenol: The mechanistic insights

A ternary dual Z-scheme composite gCN/ZnFe2O4/Bi2S3 (ZFO/BS) was synthesized via a facile microwave assisted process and its photocatalytic potential was explored towards visible light driven removal of 2,4,6-tricholorophenol (TCP) with subsequent peroxymonosulfate (PMS) activation. Surface-boundFe2+/3+|surf.,Zn+/2+|surf.andBi3+/4+|surf.were effective towards charge carrier channelization and evolution of reactive species. Highest catalytic activity was experienced for the catalyst with 10 wt% Bi2S3 (ZFO/BS(10)) and 98.9% TCP was removed with 0.25 gL−1 catalyst and 1.0 gL−1 PMS, under 60 mins visible light irradiation (intensity: 80 W). Construction of dual Z-scheme heterojunction was studied using XPS and the mechanism of e-/h+ separation was elucidated. In-depth radical scavenging and EPR analysis confirmed the coexistence and relative contributions of various reactive radicals towards degradation. Plausible TCP degradation pathway was designed based on intermediate analysis. This study elucidates the superiority of dual Z-scheme ternary heterojunction towards separation of photogenerated charge carriers and mineralization of various emerging contaminants.

Fabrication of hexagonal boron carbonitride nanoplates using for in vitro photodynamic therapy and chemo therapy

Carbon nanomaterials and boron nitride nanomaterials have been proved to be very potential for biomedical applications. However, as an analog of them, boron carbonitride nanomaterials are rarely reported in biomedical field. In this study, the fabrication of visible light-responsive boron carbonitride nanoplates (BCNNPs) and their application in photodynamic therapy and chemo therapy were demonstrated. BCNNPs with an average size of 46 nm were fabricated via hydrogen peroxide treatment from bulk BCN. Cytotoxicity tests showed that the as-prepared BCNNPs are biocompatible and have no cytotoxicity to human breast cancer cells and human hepatocyte carcinoma cells. After conjunction with doxorubicin and folic acid, the BCNNPs were adopted as a targeted drug carrier, presenting pH-responsive release and tumor-targeting property for chemo therapy. Moreover, under certain intensity of visible light irradiation (45 mW/cm2), the BCNNPs can generate reactive oxygen species including superoxide radical, hydroxyl radical and singlet oxygen, so that synergistic photodynamic/chemo therapy effects were achieved. This work may be a groundbreaking discovery for utilizing BCNNPs as photosensitizer for photodynamic therapy and drug carrier for chemo therapy.

Persistent radical cation sp2 carbon-covalent organic framework for photocatalytic oxidative organic transformations

Persistent radical covalent organic frameworks (COFs) have exhibited great application potential in the fields of photocatalysis, magnetism, and biology. However, there is still a lack of a simple, green, and effective way to produce persistent radical COFs. Here, we synthesized two sp2 carbon-covalent organic frameworks (sp2C-COFs) with persistent triphenylamine radical cation (TPA+•), which can be generated by simple light irradiation since the effective donor–acceptor heterojunction is formed in ordered skeleton. The number of persistent TPA+• will increase with the intensity of light irradiation and the photogenerated electrons generated simultaneously can be consumed by O2 to form reactive oxygen species, which can be then used to carry out the oxidative organic transformations under visible light. In addition, femtosecond-transient absorption spectra prove that the difference in the structure of the two radical cation sp2C-COFs will significantly influence the charge recombination rate, so that the materials show different catalytic efficiency.

Activating the neutral pH photozymatic activity of g-C3N4 nanosheets through post-synthetic incorporation of Pt.

The catalytic activity of photozymes can be regulated through light irradiation time and intensity, but they still suffer from low activity in physiologically neutral pH (typically, pH < 5). Herein, through simple post-synthetic incorporation of Pt, the neutral pH activity of the g-C3N4 nanosheet (CNNS) was activated. Most importantly, the catalytic activities of Pt@CNNS at pH 4.0 and 7.0 were ∼19- and 4.7-fold higher than that of CNNS at pH 4 (the optimal pH for CNNS).

Effect of headlamps on the irradiation characteristics of automotive headlights

In this study, we investigated and analyzed the correlation between high beam and low beam and the low beam irradiation characteristics of LED head lamps using a headlight tester based on each inspection standard for automotive headlights. From the experimental results, it was confirmed that the irradiation characteristics switched to the low beam did not fully satisfy the inspection criteria with respect to the appropriate irradiation direction and luminosity of the high beam. It was also found that when the halogen lamp was changed to the LED head lamp in the low beam of the 4-lamp type headlight, the change in the irradiation direction was small, but the increase in the irradiation light intensity differed depending on the vehicle.

Decoration of Ag Nanoparticle on ZnO Nanowire by Intense Pulsed Light and Enhanced UV Photodetector

Zinc oxide (ZnO) nanowires (NWs) are wide-bandgap semiconductors that absorb ultraviolet (UV) radiation. Various post-treatment processes have been studied to improve the optical properties of the as-grown ZnO NWs. Among them, Ag nanoparticles (NPs) effectively improved the optical properties on the surface of the ZnO NWs. In this study, ZnO NWs were synthesized via the hydrothermal synthesis method. ZnO NWs were decorated with Ag NPs on the surface of the ZnO NWs in a silver nitrate (AgNO3) aqueous solution by intense pulsed light (IPL) irradiation. Ag NPs were successfully decorated under the following conditions: aqueous AgNO3 solution of 100 nM, an energy of 1 J/cm2, and an exposure time of 8 ms. The responsivity and sensitivity of the ZnO NW UV photodetectors increased by 7.43 and 3.37 times, respectively. The IPL process makes it possible to decorate Ag NPs in a simple manner within an extremely short time.

A high-efficiency Z-scheme Er3+:YAlO3@(Au/SrTiO3)-Au-WO3 photocatalyst for solar light induced photocatalytic conversion of Cr(VI)

• Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 can effectively convert Cr(VI) into Cr(III). • Er 3+ :YAlO 3 can enhance photocatalytic activity of SrTiO 3 /WO 3 in conversion of Cr(VI). • Z-scheme system can inhibit recombination of photo-induced electrons and holes. • Using Au as co-catalyst and mediator can boost separation of electrons and holes. • The mechanism on solar light photocatalytic conversion of Cr(VI) was clarified. A high-efficiency Z-scheme photocatalyst, Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 , is fabricated successfully via hydrothermal and photo-deposition methods. All as-prepared samples are characterized by XRD, SEM, TEM, FT-IR, EDX, XPS, Raman spectroscopy, PL and DRS. The activity of the prepared Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is evaluated through photocatalytic conversion of Cr(VI) under simulated solar light irradiation. The meaningful influencing factors such as simulated solar light irradiation time, light intensity, sacrificial agents and cycling times are investigated. The results displayed that the existence of Er 3+ :YAlO 3 can improve the utilization ratio of solar light for wide band-gap SrTiO 3 . Moreover, the formation of Z-scheme SrTiO 3 /WO 3 photocatalytic system and the introduction of Au nanoparticles as electron mediator and co-catalyst can promote the separation of photo-induced electron and hole to obtain much high photocatalytic activity. Finally, the mechanism on conversion of Cr(VI) caused by Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is put forward. © 2021 Elsevier B.V. All rights reserved.