This PDF file contains the front matter associated with SPIE Proceedings Volume 9558, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

An optical surface rarely presents the idea optical behavior desired for the system in which it is employed. Modifying these properties is the task of an optical coating and virtually all optical surfaces in all optical systems carry such treatments. Most often the coating consists of a number of thin layers exhibiting interference effects that yield a suitable performance. Coating performance is constrained by the normal properties of interference. Such behavior could benefit considerably from the use of metamaterials and particularly those exhibiting a negative index of refraction. Unfortunately such true negative index still appears elusive. Negative refraction has been convincingly demonstrated particularly for p-polarization and this is certainly useful in a number of applications but metamaterials have not so far yielded the complete set of properties representing the true negative index that could transform the field of optical coating.

The inorganic polarization devices for visible range, namely the absorptive gird polarizers and form birefringent wave plates, were developed. These devices are composed only of inorganic materials and glancing angle deposition technique was employed to fabricate their optical functional layers, which are the absorptive layer and columnar birefringent structure for the polarizers and wave plates, respectively. The optical performance and reliability of these devices were experimentally evaluated and showed them to be suitable for applications requiring high light resistance and thermal durability, such as liquid crystal display projectors.

To further reduce the intensity of the Fresnel reflections of optical components, subwavelength structures prepared by reactive ion etching of SiO2 thin films are combined as outermost layer with a multilayer system made of conventional thin film materials and prepared by magnetron sputtering. In this approach, a hybrid coating is realized in which the nanoscaled structured outermost layer is expected to further improve the antireflection properties of common interference stacks. The subwavelength structures are examined by spectroscopic ellipsometry, spectral photometry and scanning electron microscopy. The microscopic and optical spectroscopic analysis revealed that pillar-shaped nanostructures are formed during etching which exhibit low-index properties and have a depth-dependent refractive index. To take into account the index gradient in the coating design, the optical properties of the nanostructures are modeled using the effective medium approximation. The calculated average effective refractive index is 1.11 at 500 nm wavelength. A hybrid coating was designed to minimize the residual reflectance in the 400 – 900 nm spectral range for BK7 glass substrate. Experimental results showed that the hybrid coating achieves a low residual reflectance with very good omni-directional properties, owing to the properties of its nanostructured surface. The residual reflection of the hybrid coating is found to be two times smaller than the reflection obtained by applying a common interference multilayer system which demonstrates the benefit of the use of hybrid systems for the realization of broadband antireflective coatings with wide-angle properties.

The direct optical monitoring of electron exchange on single plasmonic nanoparticles, involved in chemical reactions with gas molecules, is one of the main challenges in the heterogeneous catalysis and gas sensing fields. Catalysts are substances that speed up reactions by providing an alternative pathway with lower activation energy than that required for the uncatalysed reaction. A lot of research, both fundamental and applied, has been carried out to investigate how catalysts work and to increase their efficiency. The present work shows how the use of Dark Field Microscopy (DFM) coupled with surface plasmon spectroscopy, enables the direct observation of the kinetics of H2 gas interaction with single gold nanorods (NR) coupled with Pt nanoparticles (NPs) and/or with metal oxide matrices. The plasmonic particles, gold NRs, act as optical probes, and enable the monitoring of the electron exchange through the measurement of their surface plasmon resonance (SPR) band shift. To improve the redox reaction kinetics, the Au NRs have been coupled with Pt NPs and embedded also into a TiO2 or ZnO low scattering matrix. The Au NRs, the Pt, TiO2 and ZnO NPs have been synthetized by colloid chemistry. Several samples made of bare Au NRs, or Au NRs coupled with only Pt NPs or with Pt and TiO2 NPs or with Pt and TiO2 have been deposited by spin coating on silica substrates. The longitudinal Au SPR band shift has been monitored by DFM looking at the variation of the scattering spectrum of a single Au NRs in the presence of H2. Time-resolved measurements have been also conducted at fixed wavelength in order to monitor the kinetics of the H2 reaction. With such measurements it was possible to elucidate the importance of the adsorbed oxygen and the TiO2 matrix on the H2 reaction with the Pt NPs.

In organic photovoltaics field, an optimized bulk heterojunction film consists of an electron-donating conjugated polymer and an electron-accepting fullerene derivative, which is organized in a well phase-separated, yet interconnected network. This sensitive morphology, affecting the light absorption, exciton dissociation and subsequent charge generation-extraction, is determined by the film formation during solution casting under certain processing conditions. Therefore, a number of previous studies focused on characterizing the thin film formation during solution casting, mainly with in-situ grazing-incidence X-ray scattering methods, accompanied by various optical methods, such as ellipsometry/reflectometry and UV-VIS absorption. Although these studies provided invaluable information on the matter, the development of nanoscale morphology is yet to be fully understood. The purpose of this study is to demonstrate a portable in-situ characterization chamber, which can characterize any organic/hybrid thin film during solution casting. The chamber is a miniature doctor blade under controlled atmosphere, equipped with white light reflectometry (WLR), photoluminescence (PL) and laser light scattering (LLS). WLR was used to monitor the thickness reduction of the thin film during the drying, enabling to establish a drying curve. LLS informed the time scale of aggregate/crystallite formation. PL monitored molecular arrangement and enabled the estimation of microstructure. The combined data is used to understand the competition between thermodynamics (e.g. solubility, miscibility) and kinetics of morphology formation. In this study, we measured different BHJ systems with binary and ternary solvent mixtures under different processing conditions, from which we built a roadmap for microstructure formation in organic thin films, used in organic photovoltaics.

Ionized nitrogen doped Si-C thin films at 200°C substrate temperature were obtained by Thermionic Vacuum Arc (TVA) method. To increase the energy of N, C and Si ions, -400V, -600V and -1000V negative bias voltages was applied on the substrate. The 400nm, 600nm and 1000nm N-SiC coatings on glass was deposed. To characterize the structure of as-prepared N-SiC coatings, Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray and Photoelectron Spectroscopy (XPS) techniques was performed. Electrical conductivity was measured comparing the potential drop on the structure with the potential drop on a series standard resistance in a constant current mode. To justify the dependence of measured electrical conductivity by the temperature, we assume a thermally activated electrical transport mechanism.

Nanostructured thin film absorbers embedded with phase-change material (PCM) can provide large level of absorption intensity tunability in the near-infrared region. Germanium Antimonide Tellurite (Ge2Sb1Te4-GST) was employed as the phase-change material in the designed structures. The structure is composed of a periodic grating-type array of 200 nm thick Au buried with 100 nm-thick GST layer from the top of the Au layer. The period of the gratings is 2 μm and in each period, GST width is 0.5 μm. GST was selected as the active PCM because its optical properties undergo a substantial change during a structural transition from the amorphous to the crystalline phase. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. It was shown that absorption intensity in the near-infrared region was tuned from the near-perfect to the near-zero level by switching the PCM from its amorphous to crystalline states. The distributions of the electric field and absorbed power at the resonant wavelengths with respect to different phases of the GST were investigated to further explain the physical origin of the absorption tuning. This study provides a path toward the realization of tunable infrared absorbers for the applications, such as selective infrared emitters, infrared camouflage, sensors, and photovoltaic devices.

Metallic nanostructures are widely studied because of their peculiar optical properties. They possess characteristic absorbance spectra with a peak due to plasmonic resonance. This feature is directly dependent on the nanostructures shape, size, distribution and environment surrounding them. This makes them good candidates for a variety of applications, such as localized surface plasmon resonance sensing (LSPR), surface-enhanced Raman scattering (SERS) and photovoltaics. A well established technique used to create nanoisland on flat substrates is performing a thermal treatment after the deposition of a thin metal film. While the most widely investigated metal in this context is gold, we have extended our investigation to palladium, which is interesting for sensing applications because it has an excellent hydrogen absorption ability. The morphological properties of the nanoisland depend mainly on the starting thickness of the deposited layer and on the annealing parameters, temperature and duration. The deposition and annealing process has been investigated, and the resulting samples has been tested optically and morphologically in order to optimize the structures in view or their application for sensing purposes.

After formulating the frequency-domain Maxwell equations for a homogeneous, linear, bianisotropic material occupying a bounded region, we found that the axionic piece vanishes from both the differential equations valid in the region and the boundary conditions, thereby vindicating the Post constraint. Our analysis indicates that characteristic effects that may be observed experimentally with magnetoelectric materials are not the consequences of the axionic piece but of an admittance that describes surface states.

A simple numerical method for solving diffraction problems was developed. It is based on a multiple scattering approach and a fundamental result in homogenization theory. The method is easily implemented and is efficient for complex inhomogeneous objects.

A nanoengineered composite material was considered in the long–wavelength regime. It consisted of a random mixture of two isotropic dielectric component materials. Each component material was composed of oriented spheroidal particles. The Bruggeman formalism was used to estimate the permittivity dyadic of the corresponding homogenized composite material (HCM). If the rotational symmetry axes of the two populations of spheroids were mutually orthogonal then the HCM was an orthorhombic biaxial material; if these two symmetry axes were mutually parallel then the HCM was a uniaxial material. The degree of anisotropy of the HCM increased as the shape of the component particles became more elongated, with the greatest degrees of anisotropy being attained when the component particles were shaped as needles or discs. Hence, nanoengineered composite materials based on simple oriented component particles may be homogenized to realize extremely large degrees of anisotropy.

The determination of the complex refractive index of thin films usually requires the highest accuracy. In this paper, we report on a new and accurate method based on a spectral rectifying process of a single transmittance curve. The agreements with simulated and real experimental data show the helpfulness of the method. The case of materials having arbitrary absorption bands at midpoint in spectral range, such as pigments in guest-host polymers, is also encompassed by this method.

A basic requirement for many optical applications is the reduction of Fresnel-reflections. Besides of interference coatings, nanostructures with sub-wavelength size as known from the eye of the night-flying moth can provide antireflective (AR) properties. The basic principle is to mix a material with air on a sub-wavelength scale to decrease the effective refractive index. To realize AR nanostructures on polymers, the self-organized formation of stochastically arranged antireflective structures using a low-pressure plasma etching process was studied. An advanced procedure involves the use of additional deposition of a thin oxide layer prior etching. A broad range of different structure morphologies exhibiting antireflective properties can be generated on almost all types of polymeric materials. For applications on glass, organic films are used as a transfer medium. Organic layers as thin film materials were evaluated to identify compounds suitable for forming nanostructures by plasma etching. The vapor deposition and etching of organic layers on glass offers a new possibility to achieve antireflective properties in a broad spectral range and for a wide range of light incidence.

We obtained Gallium-doped and Aluminum-doped Zinc Oxide nanocrystals by non aqueous colloidal heat-up synthesis. These nanocrystals are transparent in the visible range but exhibit localized surface plasmon resonances (LSPRs) in the near IR range, tunable and shiftable with dopant concentration (up to 20% mol nominal). GZO and AZO inks can be deposited by spin coating, dip coating or spray coating on glass or silicon, leading to uniform and high optical quality thin films. To enhance absorbtion in the infrared region, samples can be annealed in inert or reductant atmosphere (N2/Argon or H2 in Argon) resulting in plasmon intensity enhancement due to oxygen vacancies and conduction band electrons density increment. Then IR plasmon has been exploited for gas sensing application, according to the plasmon shifting for carrier density variations, due to electrons injection or removal by the target gas/sample chemical interactions. To obtain a functional sensor at low temperature, another treatment was investigated, involving surfanctant removal by dipping deposited films in a solution of organic acid, tipically oxalic acid in acetonitrile; such process could pave the way to obtain similar sensors deposited on plastics. Finally, GZO and AZO thin films proved sensibility to H2 and NOx, and in particular circumstances also to CO, from room temperature to 200°C. Sensibility behavior for different dopant concentration and temperture was investigated both in IR plasmon wavelengths (~2400 nm) and zinc oxide band gap (~370 nm). An enhancement in sensitivity to H2 is obtained by adding Pt nanoparticles, exploiting catalytic properties of Platinum for hydrogen splitting.

Graphene–metals interfaces are investigated in many subject areas both applicative and speculative. The interest mainly stems from the possibility for CVD synthesis of large area graphene on metals. In this case the metal acts as a catalyst for complete dehydrogenetaion of hydrocarbon precursors that leaves carbon behind at the surface. Such bilayer are also very appealing for surface plasmon resonance devices, since graphene acts both as a protective layer and biorecognition element. Several pairs of graphene–metal interfaces have been studied in terms of SPR performance and physicalchemical properties at the interface. With regard to this last aspect, NEXAFS spectroscopy is a powerful method to study single-, double-, and few- layers graphene and to illustrate any evolution of the electronic states.

In this study, we demonstrate the rapid switching of flow direction in a narrow parallel plate channel filled with water by using the thermoplasmonic Marangoni effect. A gold island film prepared in the channel is used as a thermoplasmonic heater, on which a continuous wave (CW) laser is focused to generate a micro bubble. By displacing the laser spot from the bubble center, Marangoni vortex flows are developed adjacent to the bubble. The direction of the observed flow significantly changes depending on the applied laser power. When the laser power is square-wave modulated at 5 Hz, the flow direction instantaneously switches in response to the power, and polystyrene microspheres dispersed in the water are arranged in a discrete pattern. The flow direction switching is observed for laser power modulation frequency of up to 40 Hz, which indicates that the time constant of the flow direction switching is at least of the order of several milliseconds. This rapid flow direction switching is attributed to the fast response of both the thermoplasmonic effect of the gold nanoparticles and the Marangoni effect on the bubble surface. Consequently, the thermoplasmonic Marangoni flows are useful for the dynamic and flexible flow control and microparticle manipulation in a microfluidic channel.

This work reports the optoelectronic characteristics of the graphene/MAPbI₃/TiO₂/Si heterostructure and graphene/Pb₂/porous Si heterostructure for light-emitting devices with low cost. The XRD diagrams of these two heterostructures show three main peaks at the position of 14.1°, 28.4°, and 31.9°, which correlate with (110), (220), and (310) planes of the MAPbI₃ perovskite phase. The PL spectra of these two heterostructures demonstrated three peaks located at 382, 566, and 766 nm. They are corresponding to the emission of B-B transition of TiO₂, defects in the TiO₂, and B-B transition of MAPbI₃. One peak of the EL spectrum of the graphene/MAPbI₃/TiO₂/porous Si heterostructure operated under the injection current of 10 mA located at around 800 nm was observed.

Lately, graphene oxide (GO) thin films have attracted much attention: they can be used as humidity-sensitive coatings in the surface acoustic wave (SAW) sensors; being functionalized, they can be used in optoelectronic or biodevices, etc. In this research we study surface morphology of small-area thin GO films obtained on Si and quartz substrates by deposition of very small amounts of H2O-GO aerosols produced by the SAW atomizer. An important feature of this method is the ability to work with submicrovolumes of liquids during deposition that provides relatively good control over the film thickness and quality, in particular, minimization of the coffee ring effect. The obtained films were examined using AFM and electron microscopy. Image analysis showed that the films consist of GO sheets of different geometry and sizes and may form discrete or continuous coatings at the surface of the substrates with the minimum thickness of 1.0-1.8 nm which corresponds to one or two monolayers of GO. The thickness and quality of the deposited films depend on the parameters of the SAW atomization (number of atomized droplets, a volume of the initial droplet, etc.) and on sample surface preparation (activation in oxygen plasma). We discuss the structure of the obtained films, uniformity and the surface coverage as a function of parameters of the film deposition process and sample preparation. Qualitative analysis of adhesion of GO films is made by rinsing the samples in DI water and subsequent evaluation of morphology of the remained films.

We report the realization and characterization of porous nanostructures where a periodic refractive index modulation is achieved by stacking layers with different nano-architectures. One multilayer photonic crystal has been fabricated starting from colloidal dispersion of silicon dioxide and zirconium dioxide using spin coating technique. Improved efficiency of Bragg reflectivity (up to 85%) has been obtained by a new bottom-up fabrication technique of photonic hierarchical nanostructures based on self-assembly from the gas-phase at low temperature whit a very thin (≈ 1 μm) photonic crystal devices. Due to the high porosity, these systems can be infiltrated with nematic liquid crystals leading to tuning of the Bragg reflection band by applying low voltages to the structure.

Multiple surface-plasmon-polariton (SPP) waves can be guided by the interface of a metal and a chiral sculptured thin film (STF). It is possible to embed within the chiral STF a layer of silver nanoparticles as sites to bind recognition molecules for sensing analytes of a certain kind. Chiral STFs were deposited on aluminum thin films. 5-nm-thick layers of silver nanoparticles were deposited in the chiral STF at different depths in different samples. The samples were then deployed in the Turbadar–Kretschmann–Raether configuration to observe the effects the silver-nanoparticle layer had on the multiple SPP-wave modes in relation to the depth. We concluded that the silver-nanoparticle layer tends to shift the angular locations of the SPP-wave modes but does not necessarily affect the location of the SPP-wave modes to an extent that would render the data uninterpretable.

In this work we investigate the existence of an one-dimensional Porous Silicon (PS) based structure possesing simultaneously Photonic and Phononic Band Gaps at the same reduced frequency. We present rigorous electrodynamic and elastodynamics calculations of the eigenvalues of the wave equations for electromagnetic and longitudinal (transverse) mechanical vibrations. The PS structure is identified as a PhoXonic structure exhibiting ranges of forbidden frequencies for visible light and hypersound.

The self-organization of discotic liquid crystal molecules in columns has enormous interest for soft nanoelectronic applications. A great advantage of discotic liquid crystal is that defects can be self-annealed in contrast to typical organic materials. Through the overlap of molecular orbitals, the aromatic cores assemble into long range ordered one-dimensional structures. Very thin structured films can be obtained by spin-coating from solution and the resulting morphologies are strongly dependent on the interaction between discotics and solvent molecules. Toluene produces films formed by very long nanowires, spontaneously aligned along a common direction and over fairly large areas. These nanostructured films are a result of the interplay between liquid crystal self-organization and solvent driven assembly. The ordered nanowire structures exhibit improvement in the electrical properties compared to misaligned structures and even to pristine HAT5, deposited without the aid of solvent. In this study we show that the toluene-based deposition of discotic liquid crystals is advantageous because it allows a uniform coverage of the substrate, unlike pristine HAT5 but also thanks to the type of induced structures exhibiting one order of magnitude higher conductivity, in the aligned nanowire films, compared to bare HAT5 ones.

A systematic study of TiO2 films deposited by dc filtered cathodic vacuum arc (FCVA) was carried out by varying the deposition parameters in a reactive oxygen atmosphere. The influence of the oxygen partial pressure on film properties is analyzed. Composition was obtained by Rutherford backscattering spectroscopy (RBS) measurements, which also allow us to obtain the density of the films. Morphology of the samples was studied by scanning electron microscopy (SEM) and their optical properties by ellipsometry. Transparent, very dense and stoichiometric TiO2 films were obtained by FCVA at room temperature.

Bismuth oxide (Bi₂O₃) is a multi-functional oxide semiconductor with various properties of interest such as high reflective index, high photoconductive response, luminescence and high oxygen-ion conductivity, potentially useful as optical coatings, electrodes of solid oxide fuel cells (SOFC), supercapacitors, visible-light activated photocatalysts, and gas sensors. Large areas of bismuth oxide (Bi₂O₃) nanocones were grown onto Si(001) substrates by magnetron sputtering. The samples were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL). The obtained tapered nanostructures consist of high-density nanocones with diameters approximately 70–130 nm and lengths of 1–3 μm. XRD results reveal that the Bi₂O₃ nanocones can undergo a phase transition from the α to the β phase at growth temperatures over 450°C. This phase transition was confirmed by TEM and PL. The growth mechanism of Bi₂O₃ nanocones was identified as grain boundary-assisted growth, in which a Bi seeding layer is crucial to the formation of the nanostructures. The results herein suggest that introducing a surface seeding layer may provide an effective way to grow various 1D nanostructures over large areas in high yield by magnetron sputtering.

The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm² was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

A metal-dielectric (M-D) multilayer has been applied as a subwavelength structure to exhibit the negative index of refraction. Periodic MD multilayer or symmetrical five layered MDMDM multilayer has been arranged to exhibit an equivalent complex refractive index with negative real part. As the extinction coefficient is much smaller than the index of refraction, the wave vector and Poynting vector are in opposite directions. How to reduce the extinction coefficient and raise the transmittance becomes an issue. In this work, the metal films within the multilayer are not arranged with the same thickness as well as dielectric films. The thickness of each layer is tuned to increase the transmittance. The previous example of a five layered MDMDM as a negative index metamaterial at a wavelength of 363.8nm is adopted here to do the improvement of loss. The near field simulation is also adopted here to observe the backward wave propagation as a negative refraction phenomenon.

Gold nanohelical structured thin films (NHFs) were tried to be deposited on a glass substrate using glancing angle deposition technique. At a deposition angle of 89°, gold NHFs were fabricated by introducing liquid nitrogen to flow under the backside of BK7 glass substrate holder. The temperature of substrate was reduced to be less than -140°C before deposition. The spin rate was controlled with respect to the deposition rate to grow three different sized nanohelices. The morphology and optical properties of Au NHFs were measured and compared between the three samples. The strong g-factor implies high sensitivity of deposited helixes in biosensing in the future.

The substrate cooling technique was introduced in glancing angle deposition to grow a slanted silver nanorod array (NRA) by introducing liquid nitrogen to flow under the substrate. The morphologies of NRAs deposited with cooling and without cooling are compared in this paper. During deposition, the temperature on the backside of substrate was kept at -140°C. A three-sectional zig-zag nanostructured array (ZNA) was then deposited under the same cooling condition. The polarization dependent transmittance and reflectance spectra of both NRA and ZNA were also measured and compared in this work.

Anisotropic dielectric materials characterized indefinite permittivity dyadics (known as hyperbolic materials) were investigated for possible optical sensing applications. Such materials present hyperbolic dispersion relations for extraordinary plane waves which only allow plane waves to propagate in certain directions. In contrast, anisotropic dielectric materials characterized positive-definite (or negative-definite) permittivity dyadics present elliptical dispersion relations which generally allow plane waves to propagate in all directions. The transition between hyperbolic and elliptical dispersion relations may be exploited for optical sensing. This phenomenon was investigated theoretically by considering the homogenization of a porous hyperbolic material which is infiltrated by an analyte-containing fluid. The theoretical approach adopted was based on the extended version of the Maxwell Garnett homogenization formalism Factors taken into consideration include the shape, size, and orientation of pores in the hyperbolic material as well as its porosity. It was found that exceeding large values of sensitivity could be attained as the negative–valued eigenvalue of the permittivity dyadic (or its real part for dissipative materials) of the infiltrated hyperbolic material approached zero.

Cadmium Oxide (CdO) thin films with low electrical resistivity and higher transparency has been deposited by r.f. magnetron sputtering on glass substrates. Sputtering process was carried out at r.f. power of 40W and with varying substrate temperatures. The structural, morphological, electrical and optical properties of the deposited films are investigated. The structral properties reveals that the as-deposited CdO films shows preferential orientation along (111) plane exhibiting face centered cubic structure. The surface morphology shows that all the films possess well defined grain boundaries with high uniformity. CdO samples deposited at substrate temperature of 150°C with r.f. power of 40W exhibits above 95% transparency in the visible region with lower electrical resistivity value in the order of 10^-4 Ω.cm. The comparatevely high value of the figure of merit for the optimum sample of CdO deposited at 150°C indicates that these films are suitable for optoelectronic device applications.

Introduction of nanofillers into polypropylene matrix has shown to improve the partial discharge resistance and breakdown strength. This work details the various statistical techniques that can be used to effectively analyze and forecast PD data obtained. PP samples made of base polymer and loaded with 1%, 2%, 4% and 8% synthetic nanofillers were aged under surface partial discharges. The acquired partial discharge pulse amplitude spectra were quantified in terms of Weibull scale (α) and shape (β) parameters. The sequential observations of these parameters collected at regular intervals of time constituted the two time series which are used here to analyze the PD data. The theoretical framework for analyzing & forecasting time series of Weibull shape and scale parameters of partial discharge pulse amplitude spectra using the auto & cross correlations to arrive at parsimonious models that can be used to analyze and forecast the data are presented.

It is known from literature that several electrical characteristics such as partial discharge resistance and breakdown strength of polypropylene films can be improved by homogeneous dispersion of nanofillers into the polymer matrix. In this work, effect of variation in aging voltage on partial discharge characteristics of PP and its remnant breakdown strength after aging with partial discharges are investigated for unfilled (PP+0%) and natural nanofilled PP (PP+2% & PP+6%). Using partial discharge measurement set up, several AC voltages (multiples of inception voltage, Vi) were applied to each sample for a duration of two hours and partial discharge parameters were continuously acquired. After the completion of partial discharge measurement experiments, surface erosion of aged PP samples were measured using profilometer to investigate effects of change in applied voltage and nanofillers concentrations on the partial discharge resistance of polypropylene samples. Comparison of partial discharge characteristics of all unaged and aged is done and the results of our findings are explained.

The aging conditions play a prominent role on the remnant breakdown strength of the samples as the partial discharge characteristics which affect the sample performance change drastically with the type of aging voltage. During aging, the formation of space charge that causes change in partial discharge characteristics depends on the electric field applied during aging. In this work, an investigation into remnant breakdown strength of natural and synthetic nanofilled and unfilled PP is done when aged under different types of voltage profiles. Synthetic (2, 4 and 8 wt-%) and natural (0, 2 and 6 wt-%) organoclay samples were used in this experiment. The nanocomposites were aged under different aging conditions. Samples of same composition were exposed to constant voltage aging, step voltage aging, and ramp voltage aging. The various types of voltages were applied to the nanocomposites to observe how they would behave under different aging conditions. Breakdown strength analyses was done on aged and unaged samples to evaluate the effect of PD on the remnant breakdown strength of samples with and without nanocomposites.