Design and tailoring of patterned ZnO nanostructures for perovskite light absorption modulation

Lithography is a pivotal micro/nanomanufacturing technique,facilitating performance enhancements in an extensive array of devices,encompassing sensors,transistors,and photovoltaic devices.The key to creating highly precise,multiscale-distributed patterned structures is the precise control of the lithography process.Herein,high-quality patterned ZnO nanostructures are constructed by systematically tuning the exposure and development times during lithography.By optimizing these parameters,ZnO nanorod arrays with line/hole arrangements are successfully prepared.Patterned ZnO nanostructures with highly controllable morphology and structure possess discrete three-dimensional space structure,enlarged surface area,and improved light capture ability,which achieve highly efficient energy conversion in perovskite solar cells.The lithography process management for these patterned ZnO nanostructures provides important guidance for the design and construction of complex nanostructures and devices with excellent performance.

Effects of Substrate Complexing Light Rare Earth on Growth,Cd Absorption and Organ Distribution of Sweet Pepper(Capsicum annuum var.annuum)

[Objective] The aim was to research effects of substrate complexing light rare earth on growth, Cd absorption and organ distribution of sweet pepper to pro- vide references for development of rhizosphere regulation products in farmland seri- ously polluted. [Method] In the test, effects of substrate cakes （at the same size） and light rare earth （in different doses） on growth, Cd absorption and distribution of green peppers under stress from Cd were explored with a pot experiment. [Result] When 40 mg/kg of rare earth was added into a substrate cake, plant height of pep- per seedlings and the dry weight increased by 21.52% and 11.11%, compared with control group; when Cd was at 5.19 mg/kg （a highly graded pollution）, the shoot biomass, olant biomass and dry weight of fruits all enhanced significantly, but root system changed little in the groups where substrate cakes were saved, compared with the group where the substrate cake was washed away. No matter RE was added into substrate cakes or not, root system was significantly inhibited by Cd stress （5.19 mg/kg）, but RE at proper dose improved growth of green pepper and had little effect on fruit yielding. In addition, RE had little inhibition on Cd content in roots. RE at 10 mg/kg promoted Cd contents in stems and leaves, but reduced the content in fruits substantially. The regressive equation of Cd content and rare dose in leaves was as follows： y=4E-05x%0.009 6x＋0.655 6, FF=0.542 6; the regression equations of Cd content in root, stem and fruit did not make sense. [Conclusion] The experiment lays foundation for further research on heavy metals rhizosphere complexing controlling.

Using a stand-level model to predict light absorption in stands with vertically and horizontally heterogeneous canopies

Background： Forest ecosystem functioning is strongly influenced by the absorption of photosynthetically active radiation （APAR）, and therefore, accurate predictions of APAR are critical for many process-based forest growth models. The Lambert-Beer law can be applied to estimate APAR for simple homogeneous canopies composed of one layer, one species, and no canopy gaps. However, the vertical and horizontal structure of forest canopies is rarely homogeneous. Detailed tree-level models can account for this heterogeneity but these often have high input and computational demands and work on finer temporal and spatial resolutions than required by stand-level growth models. The aim of this study was to test a stand-level light absorption model that can estimate APAR by individual species in mixed-species and multi-layered stands with any degree of canopy openness including open-grown trees to closed canopies. Methods： The stand-level model was compared with a detailed tree-level model that has already been tested in mixed-species stands using empirical data. Both models were parameterised for five different forests, including a wide range of species compositions, species proportions, stand densities, crown architectures and canopy structures. Results： The stand-level model performed well in all stands except in the stand where extinction coefficients were unusually variable and it appears unlikely that APAR could be predicted in such stands using （tree- or stand-level） models that do not allow individuals of a given species to have different extinction coefficients, leaf-area density or analogous parameters. Conclusion： This model is parameterised with species-specific information about extinction coefficients and mean crown length, diameter, height and leaf area. It could be used to examine light dynamics in complex canopies and in stand-level growth models.

Tip-induced directional charge separation on one-dimensional BiVO4 nanocones for asymmetric light absorption

One dimensional(1D)semiconductor is a class of extensively attractive materials for many emerging solar energy conversion technologies.However,it is still of shortage to assess the impact of 1D structural symmetry on spatial charge separation and understand its underlying mechanism.Here we take controllably-synthesized 1D BiVO_(4)nanocones and nanorods as prototypes to study the influence of 1D symmetry on charge separation.It is found that the asymmetric BiVO_(4)nanocones enable more effective charge separation compared with the symmetric nanorods.The unexpected spatial charge separation on the nanocones is mainly ascribed to uneven light absorption induced diffusion-controllable charge separation due to symmetry breaking of 1D nanostructure,as evidenced by spatial and temporal resolved spectroscopy.Moreover,the promotion effect of charge separation on the nanocones was quantitatively evaluated to be over 20 times higher than that in BiVO_(4)nanorods.This work gives the first demonstration of the influence of 1D structural symmetry on the charge separation behavior,providing new insights to design and fabricate semiconductor materials for efficient solar energy conversion.

Light Absorption Characteristics of Multi-Morphology FeS_2 Granular Synthesized Under Hydrothermal Conditions

A. Ennaoui proposed that FeS2 owns an appropriate band gap (0.95 eV) and large absorption coefficient, it can be used for solar materials. People had studied the light absorption characteristics of the FeS2 prepared by different methods, and believed that crystal grain size, defect density and crystalline quality are important factors that affect the light absorption properties. In order to take a depth study of the absorption properties, the research group has taken a study on light absorption characteristics of natural pyrite, the existence of Co, Ni impurities results in lower band gap and conversion efficiency.

Rapid determination of C1^- by light-absorption ratio variation approach using Cl^--eosin Y-Ag^+ adsorptive precipitation

The adsorptive precipitation between eosin Y （EY） and AgCl colloids at pH 3.73 caused the sensitive color change of the solution. The reaction mechanism between EY and AgCl was analyzed and this reaction was used for determination of Cl^- in trace level by the light-absorption radio variation approach.

Measurements of NO_2 mixing ratios with topographic target light scattering-differential optical absorption spectroscopy system and comparisons to point monitoring technique

A topographic target light scattering-differential optical absorption spectroscopy （＇IbTaL-DOA~） system is de- veloped for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases. The telescope of the ToTaL-DOAS system points to targets which are located at known dis- tances from the measurement device and illuminated by sunlight. Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets, A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011. The measurement data are compared with con- centrations measured by the point monitoring technique at the same site. The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path.

Extreme Light Concentration and High Absorption of the Double Cylindrical Microcavities

We numerically study the enhancement factor of energy density and absorption efficiency inside the double cylindrical microcavities based on a triple-band metamaterial absorber. The compact single unit cell consists of concentric gold rings with a gold disk in the center and a metallic ground plane separated by a dielectric layer. We demonstrate that the multilayer structure with subwavelength electromagnetic confinement allows 104-105-fold enhancement of the electromagnetic energy density inside the double cavities and contains the most energy of the incoming light. Particularly, the enhancement factor of energy density G shows strong ability of localizing light and some regularity as the change of the thickness of the dielectric slab and dielectric constant. At the normal incidence of electromagnetic radiation, the obtained reflection spectra show that the resonance frequencies of the double microcavities operate in the range of 10-30μm. We also calculate the absorption efficiency C, which can reach 95%, 97% and 95% at corresponding frequency by optimizing the structure＇s geometry parameters. Moreover, the proposed structure will be insensitive to the polarization of the incident wave due to the symmetry of the double cylindrical microcavities. The proposed optical metamaterial is a promising candidate as absorbing elements in scientific and technical applications due to its extreme confinement, multiband absorption and polarization insensitivity.

Laser-induced forward transferred silver nanomembrane with controllable light absorption

Laser processing provides highly-controlled modification and on-demand fabrication of plasmon metal nanostructures for light absorption and photothermal convention.We present the laser-induced forward tansfer(LIFT)fabrication of silver nanomembranes in control of light absorption.By varying the hatch distance,different morphologies of randomly distributed plasmon silver nanostructures were produced,leading to well-controlled light absorption levels from 11%to 81%over broadband.The anti-reflection features were maintained below 17%.Equilibrated and plain absorptions were obtained throughout all absorption levels with a maximum intensity fluctuation of±8.5%for the 225μJ cases.The 45μJ pulse energy can offer a highly equilibrated absorption at a 60%absorption level with an intensity fluctuation of±1%.Pattern transfer was also achieved on a thin tape surface.The laser-transferred characters and patterns demonstrate a localized temperature rise.A rapid temperature rising of roughly 15℃can be achieved within 1 s.The LIFT process is highly efficiently fabricated with a typical speed value of 10^(3)to 10^(5)cm^(2)/h.The results indicated that LIFT is a well-controlled and efficient method for the production of optical films with specific absorption levels.

Generation of Nonclassical Light by Unsaturated Two-Photon Absorption

In this paper, we investigate the distribution statistics of photons in a single mode radiation field subjected to two-photon absorption (TPA) and the factors that contribute to squeezing and antibunching of photons, leading to the generation of nonclassical light. TPA is a nonlinear optical phenomenon in which the atoms interact with the light field by absorbing two photons simultaneously. The motivation to study TPA is the recent intense activity on nanocrystallites/quantum dots. Further, it is the only nonlinear optical phenomenon that can be analytically studied. The simultaneous occurrence of squeezing and antibunching is studied with small initial photon numbers by solving the master equation for TPA of a single mode radiation directly by numerical integration, without going through analytical procedure. The results are compared with those of analytical/numerical procedures available. Further, the discussion on the parameters of squeezing and antibunching for short-time (ST) as well as long-time is done comprehensively in the present work by taking up the ST approximation and summation of ST (SST) procedure along with the exact numerical method.

Effect of Sm doping into CuInTe_(2) on cohesive energy before and after light absorption

The effects of Sm doping into CuInTe_(2) chalcopyrite on the cohesive energy before and after light absorption are systematically investigated by the empirical electron theory(EET) of solids and molecules.The results show that the static energy of CuIn_(1-x)Sm_(x)Te_(2) decreases with Sm content increasing due to the valence electronic structure modulated by doping Sm into CuIn_(1-x)Sm_(x)Te_(2).The calculated optical absorption transition energy from the static state to the excited energy level in CuIn_(1-x)Sm_(x)Te_(2) accords well with the experimental absorption bandgap of CuIn_(1-x)Sm_(x)Te_(2).Moreover,it is found that the energy bandgap of CuIn_(1-x)Sm_(x)Te_(2) is significantly widened with Sm content increasing due to its special valent electron structure,which is favorable for enhancing the light absorption in a wider range and also for the potential applications in solar cells.

Dark Oscillation of Light-induced Absorption in Heavy Reduced Co: KNSBN Crystal

This paper presents dark oscillations of light-indhced absorption in heavy reduced Co: KNSBN crystal, points out there are double carriers and multiple traps in the crystal and explains the experimental results with the newly established model of double carriers and multiple traps.

Preparation and UV-light Absorption Property of Oleic Acid Surface Modified ZnO Nanoparticles

Syntheses of zince oxide（ZnO） nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry（XRD）, transmission electron microscopy（TEM）, infrared spectroscopy（IR） and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.

Variability in the Light Absorption Coefficient by Phytoplankton,Non-Algal Particles and Colored Dissolved Organic Matter in the Northern Gulf of California

Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. The changes observed in the absorption by three seawater components (phytoplankton, detritus and chromophoric dissolved organic matter or CDOM) were analyzed in relation to changes in bio-optical regions and composition of the phytoplankton community (determined based on phytoplankton pigments). Two regions with unique bio-optical characteristics were identified separated by a narrow transition zone: the Upper Gulf of California (UGC) and Northern Gulf of California (NGC). Despite the temporal changes in their spatial distribution they maintained particular characteristic. UGC is characterized by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms and dinoflagellates) and a stronger contribution of detritus to total light absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the predominance of picophytoplankton, characterized by the dominance of zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker pigment for green algae), along with a co-dominium by CDOM and phytoplankton to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus and CDOM to total light absorption what has to be considered for the selection of bio-optical models for each specific region what can also help to a better definition of the related uncertainties.

Strong visible absorption and excellent photocatalytic performance of brown TiO_2 nanoparticles synthesized using one-step low-temperature process

particle size （5.0 nm）, large specific surface area （213.45 m1 2/g）, and efficient response to broadband light over the entire ultraviolet-visible spectrum with a narrow band gap of 1.84 eV. In addition, TiO2 -180℃ exhibited the optimal reaction rate constant for the degradation of methylene blue （0.08287 mg/（Lmin））, which is six times higher than that of the mixed rutile/anatase phase TiO2 photocatalytic standard P25 （0.01342 mg/（L min））. Furthermore, cycling photodegradation ex-periments confirmed the stability and reusability of this catalyst. The unique physicochemical properties resulting from the low-temperature preparation of TiO2 -180℃, including its broadband visible absorption associated with a high concentration of oxygen vacancies, large surface area, and enriched surface -OH/H2O may be responsible for this excellent photocatalytic performance. The use of as-prepared TiO2 -180℃ for practical applications is expected after further optimization.

Methane concentration detection system based on differential infrared absorption

The infrared absorption method for methane concentration detection is an ideal way to detect methane at present. However, it is difficult to spread this method due to its high cost. In this paper, by using a wideband infrared light emitting di- ode （LED） accompanied with a PIN photo electric diode, a low-cost methane detection system was designed. To overcome the shortcomings caused by the wide working band, a differential light path was designed. By means of a differential ratio algo- rithm, the stability and the accuracy of the system were guaranteed. Finally, the validity of the system with the proposed algo- rithm was verified by the experiment results.

High-precision alkali-atom density measurement and control methods using light absorption for dual-beam SERF magnetometers

The alkali-atom density measurement method based on light absorption is highly suitable for a spin-exchange relaxationfree(SERF)atomic magnetometer because of its high-precision measurement and complete nonmagnetic interference.In this study,the optical rotation angle detection system based on polarization balance detection is utilized to realize the alkali-atom density real-time measurement without affecting magnetic field measurement.We discovered that there exists an optimal frequency detuning of the probe light,which offers the highest sensitivity in alkali-atom density measurement and the lowest susceptibility to temperature fluctuations in terms of the scale factor.In contrast to conventional light absorption measurements based on pump light,this method demonstrated a threefold improvement in alkali-atom density measurement sensitivity while remaining immune to ambient magnetic fields and incident light intensity fluctuations.Furthermore,we utilized this method to achieve closed-loop temperature control with an accuracy of 0.04℃.

Dual-symmetry-perturbed all-dielectric resonant metasurfaces for high-Q perfect light absorption

We demonstrate a high-Q perfect light absorber based on all-dielectric doubly-resonant metasurface.Leveraging bound states in the continuum(BICs)protected by different symmetries,we manage to independently manipulate the Q factors of the two degenerate quasi-BICs through dual-symmetry perturbations,achieving precise matching of the radiative and nonradiative Q factors for degenerate critical coupling.We achieve a narrowband light absorption with a>600 Q factor and a>99%absorptance atλ_(0)=1550 nm on an asymmetric germanium metasurface with a 0.2λ_(0)thickness.Our work provides a new strategy for engineering multiresonant metasurfaces for narrowband light absorption and nonlinear applications.

Optimizing intrinsic cocatalyst activity and light absorption efficiency for efficient hydrogen evolution of 1D/2D ReS_(2)-CdS photocatalysts via control of ReS_(2)nanosheet layer growth

The visible-light-driven hydrogen evolution is extremely important,but the poor charge transfer capa-bility,a sluggish evolution rate of hydrogen,and severe photo-corrosion make photocatalytic hydrogen evolution impractical.In this study,we present 1D/2D ReS_(2)-CdS hybrid nanorods for photocatalytic hy-drogen evolution,comprised of a ReS_(2)nanosheet layer grown on CdS nanorods.We found that precise control of the contents of the ReS_(2)nanosheet layer allows for manipulating the electronic structure of Re in the ReS_(2)-CdS hybrid nanorods.The ReS_(2)-CdS hybrid nanorods with optimal ReS_(2)nanosheet layer content dramatically improve photocatalytic hydrogen evolution activity.Notably,photocatalytic hydro-gen evolution activity(64.93 mmol g^(−1)h^(−1))of ReS_(2)-CdS hybrid nanorods with ReS_(2)nanosheet layers(Re/Cd atomic ratio of 0.051)is approximately 136 times higher than that of pure CdS nanorods under visible light irradiation.Furthermore,intimated coupling of the ReS_(2)nanosheet layer with CdS nanorods reduced the surface trap-site of the CdS nanorods,resulting in enhanced photocatalytic stability.The de-tailed optical and electrical investigations demonstrate that the optimal ReS_(2)nanosheet layer contents in the ReS_(2)-CdS hybrid nanorods can provide improved charge transfer capability,catalytic activity,and light absorption efficiency.This study sheds light on the development of photocatalysts for highly efficient photocatalytic hydrogen evolution.

Electronic, Thermal Expanding, and Optical Absorption Properties of Transition Metal Dichalcogenides: A First-principles Study

A comprehensive investigation was made on the electronic structure, thermal expansion coefficient and light absorption spectrum of total six transition metal dichalcogenides(TMDs) compounds with formula of MX_2(M=Mo, W, Cr, X=S, Se). First, an indirect-direct band gap transition from bulk to singlelayer was declared for all the six compounds. Moreover, the detailed lattice constants and thermal expansion coefficients provided in the paper were the key information for designing MX_2-based field effect transistors. Finally, the calculated optical absorption spectra demonstrate that these compounds can effectively utilize solar energy and are good photo catalyst candidates. All these present findings will benefit the design of new generation of novel two-dimensional materials.