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This research reports the development of anti-reflective films for solar cell application by employing the hot embossing technique with laser-patterned microstructures. The goal is to increase the light-trapping ability of crystalline silicon (c-Si) wafers by employing micro-textured polycarbonate films to decrease surface reflectance. A series of micron-sized rhombus patterns were first created on the titanium-grade-5 mold using a fiber laser, and then, polycarbonate sheets were hot embossed under the optimized conditions. In order to investigate the influence of the embossing temperature, pressure, and time on the average reflectance and surface roughness of the films, a parametric analysis was carried out through the Taguchi method. The most effective embossing parameters were the embossing temperature of $220^{\circ }$C, pressure of 50 kg/cm², and an 8 min embossing duration, which resulted in a significant decrease of 41.53% reflectivity. The findings in the existing study and a fuzzy logic-based multi-objective optimization approach also supported these findings, suggesting the scalability and efficiency of the process. It is evident that the proposed method could provide a more significant cost reduction in fabricating anti-reflective films with large-area applications to optoelectronics devices such as solar cells, LEDs, and optical sensors. This study opens the door to further studies about using micro-patterned films to enhance light management for other energy-efficient devices.

We present the polarized reflection spectra of several MPcs (M≡Co, Ni, Cu, Zn, Pb) in the Q-band region and interpret them based on conventional exciton theory. We compare the polarized reflection spectra of the phthalocyanine radical salts NiPc(AsF₆)_0.5, H₂Pc(AsF₆)_0.67 and LiPc and interpret the new absorption band near the Q-band using the relationship between the degree of oxidation and the intensity of this new band. Based on the pressure dependence of this new band and the diagnostic phonon modes, we prove a pressure-induced charge transfer in NiPc(AsF₆)_0.5. A metal–insulator phase transition is predicted from the analysis of the plasmon absorption and is confirmed by the high-pressure electrical resistivity. We propose the origin of the pressure-induced charge transfer and the mechanism of the metal–insulator transition. We find the optical transition associated with the 3d_z2 band in the reflection spectrum of CoPc(AsF₆)_0.5, which is proved by comparison with the mixed crystals Co_xNi_{1 − x}Pc(AsF₆)_0.5. A new weak intermolecular optical transition is found through the resonance enhancement of a local phonon in the mixed crystals Co_xNi_{1 − x}Pc(AsF₆)_0.5.

Pure and Al doped nanocrystalline ZnO films have been prepared on Hydrogen terminated Si(100) substrates by nebulized spray pyrolysis. The dependence of the structural, compositional and electrical properties were investigated using XRD, EDX, AFM and spectrophotometer. The X-ray diffraction data coincide well with the pattern of ZnO reported with the Standard Database. Films annealed at higher temperatures show better orientation, as revealed from X-ray diffraction patterns. Annealing the films in air improved the electrical properties. From the I-V characteristics, the nonlinear coefficient α value has been estimated. Reflectance measurements show good reflectance in the IR region for pure ZnO films, and Al doping improved the reflectance values.

Quantum and classical components are blended together in this proposed theoretical model for describing multiple quantum well solar cells (MQWSC) in a p-i-n architecture. The model characteristics are: the use of transfer matrix as a quantum method for finding allowed energies in the coupled quantum wells, the connection of the absorption coefficient in the confined 2D structure to the one in the bulk semiconductor, and the treatment of the whole cell as a pseudo-homogeneous media to determine its reflectance. The resulted model is intended to be a working tool to assess electro-optical properties of MQWSC. Numerical results which relate the performance of the MQWSC to its structure are reported.

In this work, numerical calculations and simulation based on Transfer Matrix Method have been presented to investigate a model solar cell structure. New four-layered structure containing different types of semiconductor has been presented, analyzed and discussed. The average reflectance and average transmittance in the visible light are derived and plotted versus the operating wavelength at different physical parameters. The obtained results show that the proposed structure is a promising candidate to be used for designing future solar cell structures.

Copper (Cu) nanowire arrays embedded in anodic aluminium oxide films (AAO) on aluminium substrate have been synthesized by alternating current electrochemical deposition. Two-step anodization process has been performed to get the through-hole AAO with ordered nanochannels in 0.3M oxalic acids at DC voltages 30, 40, 50 and 60V, respectively. Structural characterization of the Cu nanowires has been analyzed by scanning electron microscopy (SEM) and X-ray diffraction (or) X-ray diffractometer (XRD). Our SEM analysis has revealed that the diameters of vertically oriented Cu nanowires are 15, 25, 45 and 60nm and the length of Cu nanowires having high packing density is about 15$\mu$m. XRD measurement has indicated that polycrystalline Cu nanowires prefer growth orientation along the (111) direction. Optical measurements show that reflection of the Cu nanowires/AAO on aluminium reduces with decreasing diameter of the Cu nanowires. This effect can be associated with increased light scattering from metal nanoparticles near their localized plasmon resonance frequency depending on the size and shape of the nanoparticles.

Zinc oxide and germanium multilayer films have been deposited on glass substrate using electron beam evaporation and resistive heating system, respectively, for alternate layers. The structural optical and electrical parameters have been investigated for the deposited films. The layer formation was confirmed by employing Rutherford back-scattering technique. Optical properties exhibit quantum confinement effect by showing the separate band gaps for ZnO and Ge. Electrical conductivity increases due to combined effect of all six layers (six alternate layers of Ge and ZnO).

Noninvasive glucose monitoring development is critical for diabetic patient continuous monitoring. However, almost all the available devices are invasive and painful. Noninvasive methods such as using spectroscopy have shown some good results. Unfortunately, the drawback was that the tungsten halogen lamps usage that is impractical if applied on human skin. This paper compared the light emitting diode (LED) to traditional tungsten halogen lamps as light source for glucose detection where the type of light source plays an important role in achieving a good spectrum quality. Glucose concentration measurement has been developed as part of noninvasive technique using optical spectroscopy. Small change and overlapping in tungsten halogen results need to replace it with a more convenient light source such as LED. Based on the result obtained, the performance of LED for absorbance spectrum gives a significantly different and is directly proportional to the glucose concentration. The result shows a linear trend and successfully detects lowest at 60 to 160 mg/dL glucose concentration.

The use of color in computer vision has received growing attention. This chapter introduces the basic principles underlying the physics and perception of color and reviews the state-of-the-art in color vision algorithms. Parts of this chapter have been condensed from [58] while new material has been included which provides a critical review of recent work. In particular, research in the areas of color constancy and color segmentation is reviewed in detail.

The first section reviews physical models for color image formation as well as models for human color perception. Reflection models characterize the relationship between a surface, the illumination environment, and the resulting color image. Physically motivated linear models are used to approximate functions of wavelength using a small number of parameters. Reflection models and linear models are introduced in Section 1 and play an important role in several of the color constancy and color segmentation algorithms presented in Sections 2 and 3. For completeness, we also present a concise summary of the trichromatic theory which models human color perception. A discussion is given of color matching experiments and the CIE color representation system. These models are important for a wide range of applications including the consistent representation of color on different devices. Section 1 concludes with a description of the most widely used color spaces and their properties.

The second section considers progress on computational approaches to color constancy. Human vision exhibits color constancy as the ability to perceive stable surface colors for a fixed object under a wide range of illumination conditions and scene configurations. A similar ability is required if computer vision systems are to recognize objects in uncontrolled environments. We begin by reviewing the properties and limitations of the early retinex approach to color constancy. We describe in detail the families of linear model algorithms and highlight algorithms which followed. Section 2 concludes with a subsection on recent indexing methods which integrate color constancy with the higher level recognition process.

Section 3 addresses the use of color for image segmentation and stresses the role of image models. We start by presenting classical statistical approaches to segmentation which have been generalized to include color. The more recent emphasis on the use of physical models for segmentation has led to new classes of algorithms which enable the accurate segmentation of effects such as shadows, highlights, shading, and interreflection. Such effects are often a source of error for algorithms based on classical statistical models. Finally, we describe a color texture model which has been used successfully as the basis of an algorithm for segmenting images of natural outdoor scenes.

Laser texturing assisted with electrochemical machining (LT-ECM) is combined the high efficiency of laser machining and the high surface quality of electrochemical machining. The light-trapping structures are mainly formed by laser action and the slag produced in laser texturing is removed by electrochemical machining. In order to obtain the better textured quality, parameters optimization for LT-ECM has been carried out in this paper. Three important parameters such as pulse laser energy and applied electrochemical have been optimized to improve the optical property of mc-Si. The textured surface reflectance (TSR) and the slag removal rate (SRR) have been used as the evaluation indicators to evaluate the textured results on mc-Si by LT-ECM. The experiments were performed on 30×30mm² mc-Si wafer with pulsed Nd:YAG laser at second harmonic wavelength and NaOH solution. The experimental results showed that pulse laser energy has the most significant influence on TSR. Applied electrochemical voltage has significant influence on SRR. Optimized parameters for LT-ECM are: pulse laser energy is about 30mJ; electrochemical applied voltage is about 15V.

The use of color in computer vision has received growing attention. This chapter gives the state-of-the-art in this subfield, and tries to answer the questions: What is color? Which are the adequate representations? How is it computed? What can be done using it?

The first section introduces some basic tools and models that can be used to describe the color imaging process. We first summarize the classical photometric and colorimetric notions: light measurement, intensity equation, color signal, color perception, trichromatic theory. The growing interest in color during the last few years comes from two new classes of models of reflection, physical models and linear models, which lead to highlight algorithms as well as color constancy algorithms. We present these models in detail and discuss some of their limitations.

The second section deals with the problem of color constancy. The term “color constancy” refers to the fact that the colors perceived by humans in real scenes are relatively stable under large variations of illumination and of material composition of scenes. From a computational standpoint, achieving color constancy is an underdetermined problem: computing the spectral reflectance from the sensor measurements. We compare three classes of color constancy algorithms, based on lightness computation, linear models, and physical models, respectively. For each class, the principle is explained, and one or two significant algorithms are given. A comparative study serves to introduce the others.

The third section is concerned with the use of color in universal, i.e. mainly low-level, vision tasks. We emphasize the distinction between tasks that have been extensively studied in monochromatic images and for which the contribution of color is just a quantitative generalization, and tasks where color has a qualitative role. In the first case, additional image features are obtained, and have to be represented and used efficiently. In the latter case, it is hoped that color can help recover intrinsic physical properties of scenes. We study successively three important themes in computer vision: edges, segmentation, matching. For each of them, we present the two frameworks for the use of color.