Thin films for advanced glazing applications

© 2016 by the authors.Functional thin films provide many opportunities for advanced glazing systems. This can be achieved by adding additional functionalities such as self-cleaning or power generation, or alternately by providing energy demand reduction through the management or modulation of solar heat gain or blackbody radiation using spectrally selective films or chromogenic materials. Self-cleaning materials have been generating increasing interest for the past two decades. They may be based on hydrophobic or hydrophilic systems and are often inspired by nature, for example hydrophobic systems based on mimicking the lotus leaf. These materials help to maintain the aesthetic properties of the building, help to maintain a comfortable working environment and in the case of photocatalytic materials, may provide external pollutant remediation. Power generation through window coatings is a relatively new idea and is based around the use of semi-transparent solar cells as windows. In this fashion, energy can be generated whilst also absorbing some solar heat. There is also the possibility, in the case of dye sensitized solar cells, to tune the coloration of the window that provides unheralded external aesthetic possibilities. Materials and coatings for energy demand reduction is highly desirable in an increasingly energy intensive world. We discuss new developments with low emissivity coatings as the need to replace scarce indium becomes more apparent. We go on to discuss thermochromic systems based on vanadium dioxide films. Such systems are dynamic in nature and present a more sophisticated and potentially more beneficial approach to reducing energy demand than static systems such as low emissivity and solar control coatings. The ability to be able to tune some of the material parameters in order to optimize the film performance for a given climate provides exciting opportunities for future technologies. In this article, we review recent progress and challenges in these areas and provide a perspective for future trends and developments.Işıl Top thanks TUBITAK for the provision of funding for a studentship. Shuqun Chen thanks the China Scholarship Council for the provision of a studentship

Elaboration and characterization of SnO2:In thin films deposited by spray pyrolysis technique

In this work, we have used the ultrasonic spray technique to deposit thin films of undoped and doped SnO2 on glass substrates. To optimize the quality of SnO2 thin films, we have studied the influence of molarity, deposition time and substrate temperature on film’s physical properties.The other aim of this work is to optimize the quality of these films by studying the influence of the dopants, the annealing temperature and the type of precursor of the starting solution on the structural, optical and electrical properties in order to obtain transparent and conductive films. For this reason, we used indium as a dopant and two types of the precursor of the starting solution (SnCl2.2H2O, SnCl4.5H2O).We used several characterization techniques, such as X-ray diffraction, UV-visible spectroscopy, scanning electron microscopy, Hall Effect and the four-point technique. We have shown that undoped and doped SnO2 films are transparent in the visible range and their structure is of tetragonal type. In our work, we found that the undoped SnO2 film deposited at 450° C for 5 minutes of deposition at a concentration of 0.1 mol / l has good properties. Also, indium-doped SnO2thin films with the best properties can be prepared using SnCl4 as a precursor and at the 2% and 20% doping rate. Also, Hall Effect measurement revealed that the undoped and doped films with 10% In had n-type electrical conductivity, and when it was at 20%, In-doped SnO2 thin films showed a p-type conductivity.The results showed that the process of annealing leads to the improvement of the crystallinity, the optical and electrical properties of SnO2.In films

Effect of impurities on morphology and growth mode of (111) and (001) epitaxial-like ScN films

ScN material is an emerging semiconductor with an indirect bandgap. It has attracted attention for its thermoelectric properties, use as seed layers, and for alloys for piezoelectric application. ScN or other transition metal nitride semiconductors used for their interesting electrical properties are sensitive to contaminants, such as oxygen or fluorine. In this present article, the influence of depositions conditions on the amount of oxygen contaminants incorporated in ScN films were investigated and their effects on the electrical properties (electrical resistivity and Seebeck coefficient) were studied. The epitaxial-like films of thickness 125 +-5 nm to 155 +-5 nm were deposited by D.C.-magnetron sputtering on c-plane Al2O3, MgO(111) and r-plane Al2O3 at a substrate temperature ranging from 700 to 950 degree C. The amount of oxygen contaminants presents in the film, dissolved into ScN or as an oxide, was related to the adatom mobility during growth, which is affected by the deposition temperature and the presence of twin domain growth. The lowest values of electrical resistivity of 50 micro-ohm cm were obtained on ScN(111)/MgO(111) and on ScN(001)/r-plane Al2O3 grown at 950 degree C with no twin domains and the lowest amount of oxygen contaminant. At the best, the films exhibited an electrical resistivity of 50 micro-ohm cm with Seebeck coefficient values maintained at -40 microV K-1, thus a power factor estimated at 3.2 10-3 W m-1 K-2 (at room temperature)

無機黒色薄膜の開発と光吸収コーティングへの応用

Tohoku University博士（工学）thesi

Electrochemical and photoelectrochemical properties of nickel oxide (NiO) with nanostructured morphology for photoconversion applications

The cost-effective production of chemicals in electrolytic cells and the conversion of the radiation energy into electrical energy in photoelectrochemical cells (PECs) require the use of electrodes with large surface area, which possess either electrocatalytic or photoelectrocatalytic properties. In this context nanostructured semiconductors are electrodic materials of great relevance because of the possibility of varying their photoelectrocatalytic properties in a controlled fashion via doping, dye-sensitization or modification of the conditions of deposition. Among semiconductors for electrolysers and PECs the class of the transition metal oxides (TMOs) with a particular focus on NiO interests for the chemical-physical inertness in ambient conditions and the intrinsic electroactivity in the solid state. The latter aspect implies the existence of capacitive properties in TMO and NiO electrodes which thus act as charge storage systems. After a comparative analysis of the (photo)electrochemical properties of nanostructured TMO electrodes in the configuration of thin film the use of NiO and analogs for the specific applications of water photoelectrolysis and, secondly, photoelectrochemical conversion of carbon dioxide will be discussed. © 2018 Bonomo, Dini and Decker

Preparation and characterisation of transparent conducting oxides and thin films

Transparent conducting oxide (TCOs) thin films, including non-stoichiometric tin doped indium oxide (ITO) and aluminium doped zinc oxide (AZO), have found considerable applications in various displays, solar cells, and electrochromic devices, due to their unique combination of high electrical conductivity and optical transparency. TCO thin films are normally fabricated by sputtering, thermal vapour deposition and sol-gel method. Among them, sol-gel processing, which was employed in this project, is no doubt the simplest and cheapest processing method, The main objectives of this project were to produce indium tin oxides (ITO) and zinc aluminium oxides (AZO) nanoparticles with controlled particle size and morphology and to fabricate TCO thin films with high optical transmittance and electrical conductivity. In this research, hydrothermal method was used to synthesise ITO and AZO nanoparticles. Tin oxides, zinc oxides, ITO and AZO particles with the particle size ranging from 10 nm to several micrometers and different morphologies were synthesised through controlling the starting salts, alkaline solvents and hydrothermal treatment conditions. ITO and AZO thin films were fabricated via sol-gel technique through dip coating method. The effects of the starting salts, alkaline solvents, surfactant additives and coating and calcination conditions on the formation of thin films were investigated. XRD, TEM, FEG-SEM, DSC-TGA, UV-Vis spectrometer and four-point probe resistance meter were used to characterise the crystallinity, particle size, morphology, optical transmittance and sheet resistance of the particles and thin films. Crack-free thin films with high optical transmittance (>80% at 550 nm) and low sheet resistances (2.11 kΩ for ITO and 26.4 kΩ for AZO) were obtained in optimised processing conditions