Interaction Of Incident Light Research Articles

Design and analysis of high-efficiency perovskite solar cell using the controllable photonic structure and plasmonic nanoparticles

Device modeling of CH3NH3PbI3 based controllable photonic structure and plasmonic nanoparticles perovskite solar cells (PSC) was performed. In recent years, light trapping (LT) and plasmonic structures in PSCs have been developed and attracted widespread attention and encouraged researchers to develop and test many architectures in this area. Also, using controllable photonic structures and plasmonic nanoparticles in PSCs significantly affect the power conversion efficiency (PCE). LT by photonic structure and also the interaction of incident light with plasmonic nanoparticles (NPs) is considered as a hopeful way to enhance the PCE of PSCs in this simulation. For accurate calculation and also considering all parameters on PSC, the present simulation is done using the finite element method (FEM). The simulation results showed that using a photonic structure significantly affects the photovoltaic result of the PSC, and the PCE reached from 15.62 % for the planar structure to 16.17 % for the photonic structure. Here, we concentrate on a significant aspect of nanostructures that minimizes light loss by optimizing and managing light to achieve high PCE for the PSC. Then we used plasmonic NPs at the top of the electron layer transfer (ETL), active layer, and hole transfer layer (HTL), and the best position to achieve the highest PCE was the top of HTL. Moreover, an additional layer as a complimentary layer (CH3NH3SnI3) was used to maximize efficiency with values of short circuit current (Jsc) 27.81 (mA/cm2), open circuit voltage (Voc) 0.949 (V), fill factor (FF) 81.77 % and PCE 21.85 %. Using these combined techniques opens horizons of improvement for the PCE of PSC.

Computational study of 2D photonic crystal based biosensor for SARS-COV-2 detection

A computational study to design a 2D-photonic crystal (PC) structure with a fluorescence-based biosensor has been demonstrated for the detection of the severe acute respiratory syndrome corona virus 2 (SARS-COV-2) virus in the lungs. The proposed sensor can detect the different concentrations of the virus without any pretreatment of the sample. The virus detection is performed by measuring the mid-gap wavelength from the dispersion diagram and a redshift in the mid-gap wavelength has been observed as the concentration of virus increases in the lung tissue. The plane wave expansion method is used to determine the dispersion diagram of the proposed PC. The interaction of incident light with the proposed PC-based biosensor has been analyzed to evaluate the shift in the mid-gap wavelength. A maximum sensitivity of about 1459.3 nm/RIU is obtained for r/a = 0.45 with a mid-gap wavelength shift of 145.93 nm at = 1.49 concentration of SARS-COV-2. Moreover, a very small detection time has been observed with the proposed device as compared to conventional methods. This study provides a simple process to detect the presence of a virus within a short period and could be helpful in the development of a direct and easy-to-use portable detection kit in the future.

Plasmonic Sensors: A New Frontier in Nanotechnology

Plasmonics is the study of surface plasmons formed by the interaction of incident light with electrons to form a surface-bound electromagnetic wave [...].

Effects of the location and size of plasmonic nanoparticles (Ag and Au) in improving the optical absorption and efficiency of perovskite solar cells

Organometal halide perovskite has a vast variety of facilities and possibilities that makes them emerge in perovskite solar cell (PSC) technology. Interaction of incident light with plasmonic nanoparticles (NPs) leads to the formation of an electric field around the NPs. The electric field from plasmonic NPs can enhance the possibility of incident light absorption inside the active layer (AL). In this paper, the light scattering mechanism is used to investigate the effect of plasmonic NPs on the value of carrier generation rate and absorption in PSCs. The finite element method (FEM) under normal-angle sunlight (AM 1.5 G) was used to obtain open-circuit voltage (Voc) and short-circuit current density (Jsc) and as well as efficiency in the proposed structure PSC. The use of gold (Au) and silver (Ag) compositions in the structure of the plasmonic NP results in an increase of the AL absorption, over planar structures. In the simulation results, we showed that the performance of the device is highly dependent on the location of the plasmonic NP in different layers of the PSC as well as the radius of these NPs. Placing the NP in the hole transfer layer (HTL) with the radius of 30 nm and composition of Ag resulted Jsc of 20.31 mA/cm2, Voc of 0.94 V, and the power conversion efficiency (PCE) of 16.20%.

Iridescent cellulose nanocrystal films: the link between structural colour and Bragg’s law

Structural colour is a phenomenon found in nature, which provides plants and animals with vibrant optical properties. The production of this colour is based on the interaction of incident light with the hierarchical organisation of submicron- and micron-sized layered structures. Cellulose nanocrystals (CNCs) are anisotropic building units formed by acid hydrolysis of native cellulose microfibers, which can disperse in aqueous media to form a photonic liquid crystal. One fascinating example of the appearance of biomimetic colour is the supramolecular assembly of CNCs into iridescent layered structures that rotate along a helical screw to yield a long-range chiral nematic order. A quick, simple and engaging experiment that allows the establishment of a direct relation between the structural colour and underlying mechanism of the light interaction with these hierarchically structured materials is reported. The obtained colour changes are explained within the theoretical framework provided by Bragg’s law and may provide an easy way to observe the macroscopic manifestation of this often abstract concept.

Sparkling Reflective Stacks of Purine Crystals in the Nudibranch Flabellina iodinea.

Although pigments contribute to much of the brilliant purple and orange coloration of the aeolid nudibranch Flabellina iodinea, the optical appearance of the animal was found to be augmented by dynamically sparkling, brightly reflective material in cells located throughout its epidermis. Electron microscopy revealed that specialized cells most abundant near the epithelial basal lamina contain numerous multilayer stacks of crystals, each within a fragile membrane capsule. High-resolution light microscopy of tissue sections showed that these crystalline stacks intermittently reflect light, with a temporally dynamic, sparkling appearance, suggesting that they are free to move-a phenomenon also observed in the live, intact whole animal and in the purified crystal stacks as well. Thin-layer chromatography and ultraviolet spectrometry show that the crystals isolated from all epithelial tissues are identical in composition, with guanine being the major component and its derivative, hypoxanthine, a minor component, regardless of the tissue's pigmentary color. Electron diffraction of the crystals purified separately from the orange and purple tissues exhibits nearly identical lattice parameters that closely match those measured for guanine crystals, which are widely distributed in other biophotonic systems ranging from marine invertebrates to terrestrial vertebrates. Heterogeneity of the thickness and spacing of the crystals within their stacks accounts for their broadband silvery reflectance. The optical appearance of the epidermis of this nudibranch thus results from the interaction of incident light with mobile stacks of purine crystals, augmenting the effects of its pigmentary colors.

Prompting peroxidase-like activity of gold nanorod composites by localized surface plasmon resonance for fast colorimetric detection of prostate specific antigen.

The interaction between incident light and surface electrons in conductive nanoparticles produces localized plasmon oscillations with a resonant frequency that strongly depends on the composition, size, geometry, and dielectric environment. Hybrid heterostructure materials combining two or more materials in one structure represent a powerful way to achieve unique properties and multifunctionality compared to those of the individual nanoparticle components. Hybrid gold nanorods and gold nanoclusters (GNR/AuNCs) heterostructures prepared by intimate integration of GNRs with AuNCs exhibit both localized surface plasmon resonance (LSPR) property and peroxidase-like activity. It is found that the catalytic activity of the AuNC/GNR heterostructure could be remarkably enhanced by LSPR induced by photon-plasmon coupling in the visible to near-infrared (NIR) region. Meanwhile, the catalytic activity of enzyme-like AuNC/GNRs may be regulated by immunoreactions to realize specific recognition of a target analyte. Accordingly, a fast colorimetric assay within 5 min for the detection of prostate specific antigen (PSA) was developed based on a AuNC/GNRs heterostructure mask regulated by the target molecule under photon-plasmon coupling. The color intensity is inversely proportional to the PSA concentration, and quantitative analysis may be achieved in a range of 10 and 200 pg mL-1. This sensor was practically applied to detect PSA levels in prostate cancer serum samples and the determined values agreed well with those measured by the hospital using standard methods. This indicates that the AuNC/GNRs heterostructure-based assay has high accuracy for the analysis of practical samples. Moreover, the new method has the advantages of very fast determination and low sample volume requirements.

Short-range spin-phonon coupling in in-plane CuO nanowires: a low-temperature Raman investigation

We report an application of low-temperature Raman scattering on in-plane CuO nanowires, in which an overview of the characteristic parameter of spin-phonon coefficient, the interaction of incident light with the spin degrees of freedom, and size effects will be given. The appearance of spin-phonon coefficient decrease reflects the existence of finite size effect.

Complete modeling of subsurface microscopy system based on aplanatic solid immersion lens

A general model of a subsurface microscopy system based on an aplanatic solid immersion lens (ASIL) is presented. This model is composed of three components: generation of incident light into the ASIL, interaction of the incident light with the sample, and imaging of the scattered light. Interaction of incident light with sample can be calculated numerically using electromagnetic scattering theory, while vector diffraction theory is used to treat the other two components. Examples of imaging small and extended scatterers are shown. For small scatterers, we show the differences between the actual resolution of the whole system and the resolution predicted by considering only one subsystem of the whole system. For extended scatterers, two types of illuminations-focusing light illumination and plane wave direct illumination-are used to image the scatterers, and observations are explained using interaction of the incident light with the sample.

Two-fold mechanism of the interaction of incident light with a phase diffraction grating

It is suggested to use antireflection diffraction gratings for introducing light into the active regions of optoelectronic devices. The dependence of the diffraction efficiency on the grating groove depth, which controls the reflection from the optical surface and forms the diffraction order in the material, has been numerically modeled.

Homogeneous Silver-Coated Nanoparticle Substrates for Enhanced Fluorescence Detection

A simple method has been developed for the deposition of uniform silver-coated nanoparticles on glass substrates, with a homogeneous distribution shown by scanning electron microscopy (SEM). UV-visible spectroscopy and energy-dispersive X-ray analysis (EDX) have been used to characterize both the optical density and elemental content of the deposited nanoparticles. The fluorescence enhancement was investigated using a monolayer of FITC-conjugated human serum albumin (FITC-HSA) and tested using laser scanning microscopy at 488 nm excitation wavelength. The enhancement factor was calculated from individual spectra recorded with a Fluorolog-Tau-3 spectrofluorometer. We identified the nanoparticle growth regime which led to fluorescence enhancement. Such enhancement is detectable when Au core-Ag shell nanoparticles increased their size to 47 nm, in agreement with theoretical estimates. The origin of this enhancement for appropriate size nanoparticles is attributed to the effect of an increased excitation rate from the local field enhanced by the interaction of incident light with the nanoparticles and/or higher quantum yield from an increase of the intrinsic decay rate of the fluorophore. We thus demonstrated that the Au core-Ag shell nanostructures on glass surfaces are promising substrates for fluorescence enhancement with outstanding macroscopic homogeneity. This important feature will pave the way for the application of our substrates in biotechnology and life sciences such as imaging and sensing of biomolecules in proteomics.

Modelling the light absorption in organic photovoltaic devices

Electromagnetic reflection, transmission and absorption properties are basically important for the optical characterization of multilayers used in optoelectronic and photovoltaic devices. They describe the interaction of incident light with the layers of the system. Depending on the thicknesses and optical constants of the individual layers, the interaction of a light source with a multilayer causes distinct distributions of the electric field and energy absorption density. Consequently the optical modelling of an organic bilayer photovoltaic device, in which the incident sunlight must be absorbed in a very narrow region near the active interface, has to take into account the influence of the optical parameters and the thicknesses of the device layers in order to gain optimal energy conversion. We focussed on the electrodynamic behavior of organic photovoltaic bilayer devices with varied layer thicknesses. We found a sensitive response of the maxima of the absorption density inside the solar cell to even fine changes in the thicknesses of the active layers. We also investigated the electrodynamic behavior of a photovoltaic device in dependence on the incident light wavelength. As a new and interesting result, our investigations showed a good correlation between measured photo current and calculated absorption density and no good correlation between measured photo current and calculated square of the electric field.

Effect of Different Roughnesses on the Excitation by Photons of the Surface Plasmon of Aluminum

Different roughnesses induce changes of the interaction of incident light with surface-plasma oscillations. We observed those changes in the optical properties of aluminum. Identical aluminum films were deposited in ultrahigh vacuum (uhv) on substrates of varying roughnesses. We measured the reflectance at photon energies in the vicinity of the surface plasmon energy (1000–1600 A). We used overcoated substrates of different dielectrics (CaF2, MgF2, and LiF). In the terms of existing theories, we show that the curves are conveniently interpreted by taking into consideration (a) the light scattering by the surface characterized by the rms roughness σ and (b) the plasmon-photon interaction closely related to the roughness σand correlation length a. Thus, within the limit of accuracy (ΔR = ±0.5%) the roughness can be determined; σ is a function of the dielectric’s thickness with Δσ<0.5 A and the correlation length a (5 A<Δa<10 A) appears to be a characteristic of the nature of the dielectric. A study under an electron microscope confirms the theoretical strong value of roughnesses and shows the condensation process of aluminum on the rough substrates.