Download or read book Synthesis and Characterization of CdSe coated ZnO Nanowires for Extremely Thin Absorber Solar Cells written by Ishai Padawer and published by . This book was released on 2009 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrochemical Characterization of CdSe coated ZnO Nanowire Extremely thin absorber Solar Cells written by Treavor Zachary Jones and published by . This book was released on 2014 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Zinc Oxide Nanostructured Extremely Thin Absorber Solar Cells written by Leah Spangler and published by . This book was released on 2013 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extremely thin absorber (ETA) solar cells are a relatively new and promising technology that could potentially lead to lower cost solar cells by using cheaper, more abundant materials and solution based processing steps. In this thesis, two aspects of a zinc oxide (ZnO) nanostructured solar cell with a cadmium selenide (CdSe) absorber layer were studied. The first was an attempt to control the density of ZnO nanowires using polystyrene (PS) microspheres, and the second incorporated a cadmium sulfide (CdS) buffer layer to improve solar cell characteristics. Using simple techniques of vertical deposition and dipcoating, PS microspheres were deposited onto ZnO seeded substrates. The desired close packed hexagonal monolayer was obtained using vertical deposition, but the monolayer was not uniform over the entire substrate. Dipcoating yields a very uniform deposition of PS microspheres, but a dense pack can only be achieved with a fast withdrawal rate and slow, controlled evaporation after dipcoating. When growing nanowires using the typical chemical bath deposition technique, it was found that the PS microspheres were unable to block the growth of ZnO nanowires. A CdS buffer layer was incorporated into the ETA cell by using the successive ionic layer adsorption and reaction (SILAR) technique. It was confirmed by both visual and UV-vis inspection that increasing the number of SILAR cycles increases CdS thickness. Scanning electron microscopy (SEM) of 33 cycles of CdS showed that aggregates form on top of the nanowires, which are not present after only 16 cycles. The CdS thickness after 16 cycles was measured using transmission electron microscopy (TEM) to be 5 nm, corresponding to a rate of deposition of 3.12 Å/cycle. Incorporating the CdS layer into both the ZnO nanowire/CdSe structure and indium tin oxide (ITO)/CdSe structure showed improved solar cell characteristics and decreased shunting. This improvement could result from an improved interface between the ZnO/CdSe and ITO/CdSe. In the case of the ZnO structure, CdS may block etching of ZnO, which is known to occur in the CdSe electrodeposition bath. In both structures, the improvement could also be a result of improved band alignment in the cell, favoring charge separation and transport.

Download or read book Synthesis and Characterization of Zinc Oxide Nanowires and Their Use in Spintronic and Photovoltaic Applications written by Benjamin Daniel Yuhas and published by . This book was released on 2009 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Growth and Optical Characterization of Zinc Oxide Nanowires for Anti reflection Coatings for Solar Cells written by Martha Coakley and published by . This book was released on 2011 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optical properties of solar cells greatly affect their efficiencies. Decreasing the broadband and directional reflectance of solar cells increases the solar irradiance transmitted and absorbed by the cell, thereby increasing the production of electron-hole pairs. Traditional optical enhancements such as light trapping and anti-reflection coatings reduce the reflectance of silicon at an optimized wavelength and angle of incidence. They do not perform as well at high angles of incidence or over the broadband solar spectrum. Theoretical studies suggest that layers with a suitable gradient-index of refraction can create both a broadband and directional anti-reflective coating. Through their variations in height and tapered growth, Zinc oxide (ZnO) nanowires can create a gradient index anti-reflection coating. ZnO is a wide-band gap semiconductor that is non-absorbing over most of the solar spectrum. With low cost, low temperature techniques, ZnO nanowires can be grown with a variety of morphologies. ZnO nanowires were grown by aqueous chemical growth and by electrodeposition on silicon to create a gradient-index anti-reflective coating for solar cell applications. The nanowire arrays were characterized using SEM images, goniometer scattering measurements, and integrating sphere total reflectance measurements. ZnO nanowires grown by aqueous chemical growth on silicon had average diameters between 60 nm and 100 nm and average lengths between 800 nm and 1100 nm. The nanowires had vertical alignment. They exhibited relatively small diffuse reflectivities and relatively large specular reflectivities. ZnO nanowires grown by electrodeposition had greater variances in length and diameter, with average diameters between 85 nm and 180 nm and average lengths between 500 nm and 1200 nm. Electrodeposited ZnO nanowires were randomly arrayed and exhibited relatively large diffuse reflectivities and relatively small specular reflectivities. Total reflectance measurements showed that all nanowire arrays reduced the broadband reflectance of silicon. Smaller nanowire arrays outperformed the larger crystal growths. A five-fold decrease in the broadband reflectance of silicon was obtained from both vertical and randomly oriented nanowire arrays. The reflectances were constant for angles of incident below 35°. Measurements at angles of incidence greater than 35° are required to determine whether ZnO nanowires can perform as directional anti-reflective coatings and whether the morphology of the nanowires affects the directional reflectances.

Download or read book Fundamental Properties of Functional Zinc Oxide Nanowires Obtained by Electrochemical Method and Their Device Applications written by Nadarajah Athavan and published by . This book was released on 2012 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on the fundamental properties and device applications of semiconductor nanoparticles. ZnO nanowires and CdSe quantum dots were used, prepared, characterized, and assembled into novel light-emitting diodes and solar cells. ZnO nanowire films were grown electrochemically using aqueous soluble chloride-based electrolytes as precursors at temperatures below 90o C. Dopants were added to the electrolyte in the form of chloride compounds, which are AlCl3, CoCl2, CuCl2, and MnCl2. The optical, magnetic, and structural properties of undoped and transition-metal-ion doped ZnO nanowires were explored. Our results indicate that the as-grown nanowire structures have considerable internal strain, resulting in clearly visible lattice distortions in bright and dark-field transmission electron micrographs. Photo and electroluminescence studies indicate that the strain-induced defects strongly dominate any dopant-related effects. However, annealing at moderate temperature as well as laser annealing induces strain relaxation and leads to dopant activation. Hence, the optical and electrical properties of the nanowires significantly improve, allowing these nanowires to become feasible for use in the fabrication of solar cell and LED devices. In addition, the magnetic impurities incorporated into our ZnO nanowires show superparamagnetic behavior at room-temperature, while Al-doped and undoped ZnO nanowires show no magnetic behavior. The electroluminescence (EL) is achieved from a vertical hybrid p-n junction LED arrangement consisting of a hole-conducting polymer and n-type ZnO nanowires, our group was the first to report this vertical nanowire-based LED in Könenkamp et al., 2004 [12]. The observed EL spectra show an ultraviolet excitonic emission peak and a broad defect-related emission band in the visible range. After annealing at 380o C, the defect related EL peak exhibits a characteristic shift to higher wavelengths, where the magnitude of the shift is dependent on the dopant type. Aluminum incorporation exhibited the most improved exciton related-emission, leading to the emergence of a narrow excitonic luminescence peak around 390 nm, which is close to the bandgap of ZnO. The comparison of spectra obtained from temperature-dependent photoluminescence (PL) measurements, before and after thermal annealing, also indicates that the optical activity of impurities changes noticeably upon annealing. The internal quantum efficiency for PL is measured to be as high as 16 percent for Al-doped samples annealed at 380o C. The PL measurements also show that the excitonic luminescence is preferentially guided, while the defect related emission is more isotropically emitted. The nanostructured heterojunction solar cell is designed such that thin CdSe quantum dot films are embedded between a ZnO nanowire film and a hole-conducting polymer layer. This arrangement allows for enhanced light absorption and an efficient collection of photogenerated carriers. Here, we present a detailed analysis of the pyridine solution and 1,2- ethanedithiol ligand exchange processes of the quantum dots, deposition processes of this quantum dot layer, the conformality of this layer on deeply nanostructured samples, and the effect of a surfactant-aided thermal annealing process. Annealing creates a structural conversion of the quantum dot layers into an extremely thin continuous poly-crystalline film, with typical grain diameters of 30-50 nm. This transition is accompanied by a loss of quantum confinement and a significant improvement of the charge transport in the CdSe layer. The combination of the solution and ligand exchange of CdSe quantum dots, as well as the deposition and optimized annealing processes of this quantum dot layer, resulted in solar cells with an open-circuit voltage up to 0.6 V, a short circuit current of ~15 mA/cm2, an external quantum efficiency of 70 percent, and an energy conversion efficiency of 3.4 percent. This 3.4 percent efficiency is presently one of the best efficiencies obtained for this type of device.

Download or read book Materials for Sustainable Energy Applications written by David Munoz-Rojas and published by CRC Press. This book was released on 2017-03-27 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impending energy crisis brought on by the running out of finite and non-homogenously distributed fossil fuel reserves and the worldwide increase in energy demand has prompted vast research in the development of sustainable energy technologies in the last few decades. However, the efficiency of most of these new technologies is relatively small and therefore it needs to be increased to eventually replace conventional technologies based on fossil fuels. The required efficiency increase primarily relies on the ability to improve the performance of the functional materials which are at the heart of these technologies. The purpose of this book is to give a unified and comprehensive presentation of the fundamentals and the use and design of novel materials for efficient sustainable energy applications, such as conversion, storage, transmission, and consumption. The book presents general coverage of the use and design of advanced materials for sustainable energy applications. Thus, the book addresses all the relevant aspects, such as materials for energy conversion, storage, transmission, and consumption.

Download or read book Controlled Synthesis of ZnO Nanowires Towards the Fabrication of Solar Cells written by Dongshan Yu and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, quasi-one-dimensional materials have attracted a lot of research attention due to their remarkable properties, and their potential as building blocks for nanoscale electronic and optoelectronic devices. A modified chemical vapor deposition (CVD) method has been used to synthesize ZnO nanowires. Electron microscopy and other characterization techniques show that nanowires having distinct morphologies when grown under different conditions. The effects of reaction parameters including reaction time, temperature, carrier gas flow rate, substrates and catalyst material upon the size, shape, and density of ZnO nanowire arrays have been investigated. Excitonic solar cells -including Gratzel-type cells, organic and hybrid organic/inorganic solar cells- are promising devices for inexpensive, large-scale solar energy conversion. Hybrid organic/inorganic solar cells are made from composites of conjugated polymers with nanostructure metal oxides, in which the polymer component serves the function of both light absorber and hole conductor, and the ZnO nanowire arrays act as the electron conductors. Organic solar cells have been fabricated from environmentally friendly water-soluble polymers and ZnO nanowire arrays.

Download or read book Nanoengineering of ZnO Electrical and Optical Characteristics by Controlling Its Morphology and Defects Via Reaction Kinetics Fluid Dynamics and Stoichiometry in Low pressure CVD Synthesis written by Taehoon Lim and published by . This book was released on 2016 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: LPCVD synthesis and characterization of ZnO with diverse morphology for semiconducting applications are studied and discussed in this dissertation. Because nanoscale ZnO shows variant characteristics depending on its physical dimensions, morphology, and impurity concentration, the focus of this work is to control the structure and composition of ZnO by adjusting synthesis parameters and methods. In Chapter 2, the synthesis of ZnO with optimized concentration of oxygen vacancies and physical dimensions are discussed. Opaqueness of ZnO is derived from scattering due to its physical dimensions, but visible transparency for the photocatalytic application of ZnO for solar cell devices is required. By controlling the concentration of oxygen vacancies and physical dimensions, fluorescent and transparent ZnO is successfully synthesized. In Chapter 3, a method to stabilize precursor supply and to lower the reaction temperature is discussed. In CVD synthesis, the stable and continuous growth of ZnO is inhibited by the premature oxidation of Zn, and the formation of a zinc oxide layer that blocks the evaporation of Zn precursor. By controlling the fluid dynamics of precursor vapors, a low temperature synthesis method with higher product uniformity is developed. Using this method, a stable synthesis technique for producing high quality ZnO under low temperature is successfully achieved. In Chapter 4, the synthesis of ZnO under relatively low temperature is discussed. During LPCVD synthesis it is observed that as the distance from the source increases, the partial vapor pressure of Zn near the surface of the deposition substrate is drastically decreased (along the axis of gas flow), forming a dimensional gradient on a single substrate. The changing reactant ratio near the surface drives the non-uniformity of product in terms of morphology, physical dimensions, and impurity concentration. In Chapter 5, a novel template-free self-catalyzed synthesis technique for achieving ultra-thin ZnO nanowires is discussed. From the tip of synthesized hexagonal cone ZnO, ultra-thin ZnO nanowires are grown by self-catalysis.

Download or read book Semiconductor Nanowires written by J Arbiol and published by Elsevier. This book was released on 2015-03-31 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanowires promise to provide the building blocks for a new generation of nanoscale electronic and optoelectronic devices. Semiconductor Nanowires: Materials, Synthesis, Characterization and Applications covers advanced materials for nanowires, the growth and synthesis of semiconductor nanowires—including methods such as solution growth, MOVPE, MBE, and self-organization. Characterizing the properties of semiconductor nanowires is covered in chapters describing studies using TEM, SPM, and Raman scattering. Applications of semiconductor nanowires are discussed in chapters focusing on solar cells, battery electrodes, sensors, optoelectronics and biology. - Explores a selection of advanced materials for semiconductor nanowires - Outlines key techniques for the property assessment and characterization of semiconductor nanowires - Covers a broad range of applications across a number of fields

Download or read book Nanomaterials for Solar Cell Applications written by Sabu Thomas and published by Elsevier. This book was released on 2019-06-12 with total page 761 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanomaterials for Solar Cell Applications provides a review of recent developments in the field of nanomaterials based solar cells. It begins with a discussion of the fundamentals of nanomaterials for solar calls, including a discussion of lifecycle assessments and characterization techniques. Next, it reviews various types of solar cells, i.e., Thin film, Metal-oxide, Nanowire, Nanorod and Nanoporous materials, and more. Other topics covered include a review of quantum dot sensitized and perovskite and polymer nanocomposites-based solar cells. This book is an ideal resource for those working in this evolving field of nanomaterials and renewable energy. - Provides a well-organized approach to the use of nanomaterials for solar cell applications - Discusses the synthesis, characterization and applications of traditional and new material - Includes coverage of emerging nanomaterials, such as graphene, graphene-derivatives and perovskites

Download or read book Nanowires written by Felix Ryler and published by . This book was released on 2016-10-01 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: The properties of nanowires have caused researchers and companies to consider using this material in several fields. Nanowires are nanostructures that have a thickness or diameter constrained to tens of nanometers or less and an unconstrained length. In addition, many different types of nanowires exist, including metallic, semiconducting and insulating. Nanowires hold lot of promises for different applications. Basic electronic devices like junction diodes, transistors, FETs and logic gates can be fabricated by using semiconductor and superlattice nanowires. Thermoelectric cooling system can be fabricated by using metallic nanowires. Semiconductor nanowire junctions can be used for different optoelectronic applications. Moreover, periodic arrays of magnetic nanowires hold high potential for recording media application. Nanowires are also potential candidates for sensor and bio-medical applications. Depending on what it's made from, a nanowire can have the properties of an insulator, a semiconductor or a metal.Nanowires - Implementations and Applications presents current research in the study of the properties, synthesis and application of nanowires. Topics discussed include semiconductor nanowires and heterostructure based gas sensors; transport properties of nanostructured materials; nanowire array electrodes in biosensor applications and analogies between metallic nanowires and carbon nanotubes.

Download or read book Chemical Solution Deposition of Functional Oxide Thin Films written by Theodor Schneller and published by Springer Science & Business Media. This book was released on 2014-01-24 with total page 801 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first text to cover all aspects of solution processed functional oxide thin-films. Chemical Solution Deposition (CSD) comprises all solution based thin- film deposition techniques, which involve chemical reactions of precursors during the formation of the oxide films, i. e. sol-gel type routes, metallo-organic decomposition routes, hybrid routes, etc. While the development of sol-gel type processes for optical coatings on glass by silicon dioxide and titanium dioxide dates from the mid-20th century, the first CSD derived electronic oxide thin films, such as lead zirconate titanate, were prepared in the 1980’s. Since then CSD has emerged as a highly flexible and cost-effective technique for the fabrication of a very wide variety of functional oxide thin films. Application areas include, for example, integrated dielectric capacitors, ferroelectric random access memories, pyroelectric infrared detectors, piezoelectric micro-electromechanical systems, antireflective coatings, optical filters, conducting-, transparent conducting-, and superconducting layers, luminescent coatings, gas sensors, thin film solid-oxide fuel cells, and photoelectrocatalytic solar cells. In the appendix detailed “cooking recipes” for selected material systems are offered.

Download or read book Colloidal Quantum Dot Optoelectronics and Photovoltaics written by Gerasimos Konstantatos and published by Cambridge University Press. This book was released on 2013-11-07 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Captures the most up-to-date research in the field, written in an accessible style by the world's leading experts.

Download or read book Nanoparticles for Biomedical Applications written by Eun Ji Chung and published by Elsevier. This book was released on 2019-11-19 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoparticles for Biomedical Applications: Fundamental Concepts, Biological Interactions and Clinical Applications brings into one place information on the design and biomedical applications of different classes of nanoparticles. While aspects are dealt with in individual journal articles, there is not one source that covers this area comprehensively. This book fills this gap in the literature. - Outlines an in-depth review of biomedical applications of a variety of nanoparticle classes - Discusses the major techniques for designing nanoparticles for use in biomedicine - Explores safety and regulatory aspects for the use of nanoparticles in biomedicine

Download or read book Chemically Deposited Nanocrystalline Metal Oxide Thin Films written by Fabian I. Ezema and published by Springer Nature. This book was released on 2021-06-26 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book guides beginners in the areas of thin film preparation, characterization, and device making, while providing insight into these areas for experts. As chemically deposited metal oxides are currently gaining attention in development of devices such as solar cells, supercapacitors, batteries, sensors, etc., the book illustrates how the chemical deposition route is emerging as a relatively inexpensive, simple, and convenient solution for large area deposition. The advancement in the nanostructured materials for the development of devices is fully discussed.

Download or read book Compound Semiconductor Photonics written by Chua Soo-Jin and published by CRC Press. This book was released on 2020-03-26 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceeding is a collection of selected papers presented at Symposium O of Compound Semiconductor Photonics in the International Conference on Materials for Advanced Technology (ICMAT), which was held in Singapore from 28 June to 3 July 2009. The symposium covers a wide range of topics from fundamental semiconductor materials study to photonic device fabrication and application. The papers collected are of recent progress in the active and wide range of semiconductor photonics research. They include materials-related papers on III-As/P, III-nitride, quantum dot/wire/dash growth, ZnO, and chalcogenide, and devices-related papers on photonic crystals, VCSEL, quantum dot/dash lasers, LEDs, waveguides, solar cells and heterogeneous integrat