M. Ocampo

Bio: M. Ocampo is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Thin film & Glazing. The author has an hindex of 2, co-authored 2 publications receiving 196 citations.

Prospects of chemically deposited metal chalcogenide thin films for solar control applications

Abstract: Solar control coatings, required for architectural glazing applications in warm climates, must provide controlled optical transmission ( approximately 10-50%) of the solar radiation in the visible region and should reflect efficiently in the infrared (>0.7 mu m) region to create a cool interior in the buildings. Thin films of PbS and CuxS on glass substrates, deposited from chemical baths, are shown to possess excellent solar control characteristics-superior or comparable to the metallic solar control coatings. For example, for an acceptable range of integrated optical transmittance ( approximately 10-20%) in the visible region, the integrated infrared reflectance for AM2 solar spectrum for the different glazings are: PbS coated glass, 50%; CuxS coated glass, 14%; stainless steel/Cu coated glass, 25% and tinted glass, 4%. The CuxS and PbS coatings also have the advantage of giving pleasant reflected colours (golden, purple, blue, etc), which improves the cosmetic appearance. This paper presents the basic requirements of solar control coatings and provides a comparison of the characteristics of PbS and CuxS coatings against commercially available coatings.

Solar control characteristics of chemically deposited lead sulfide coatings

Abstract: Chemically deposited lead sulfide thin films on glass substrates are found to satisfy the basic requirements for solar control coatings for window glazing applications in warm climates, where a low transmittance ( ∼10%–30% ) in the visible region is to be coupled with an appreciable reflectance for infrared radiation The depositions were made on glass substrates from alkaline/ ammoniacal baths of lead acetate, thiourea and small amounts of triethanolamine The coating can produce a gray, purple or bluish appearance in reflected daylight with near normal specular reflectance (visible region) of ∼15%–25% These coatings appear yellowish in transmitted daylight with 7%–25% transmittance, depending on the duration of deposition The integrated infrared (070 to 25 μm) reflectance for air mass (AM) 2 solar spectrum of typical PbS coated glass is ∼37% as compared to ∼7% for the uncoated glass The advantages of chemical deposition for large area coatings, the desirable features of PbS as a solar control coating, and toxicity considerations are discussed

Chemical deposition method for metal chalcogenide thin films

Abstract: Metal chalcogenide thin films preparation by chemical methods are currently attracting considerable attention as it is relatively inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors or metals can be used since these are low temperature processes which avoid oxidation and corrosion of substrate. These are slow processes which facilitates better orientation of crystallites with improved grain structure. Depending upon deposition conditions, film growth can take place by ion-by-ion condensation of the materials on the substrates or by adsorption of colloidal particles from the solution on the substrate. Using these methods, thin films of group II–VI, V–VI, III–VI etc. have been deposited. Solar selective coatings, solar control, photoconductors, solid state and photoelectrochemical solar cells, optical imaging, hologram recording, optical mass memories etc. are some of the applications of metal chalcogenide films. In the present review article, we have described in detail, chemical bath deposition method of metal chalcogenide thin films, it is capable of yielding good quality thin films. Their preparative parameters, structural, optical, electrical properties etc. are described. Theoretical background necessary for the chemical deposition of thin films is also discussed.

Atmospheric Pressure Chemical Vapor Deposition of Tin Sulfides (SnS, Sn2S3, and SnS2) on Glass

Abstract: Atmospheric pressure chemical vapor deposition of SnS2, Sn2S3, and SnS has been achieved onto glass substrates from the reaction of SnCl4 with H2S at 300−545 °C. The films show good uniformity and surface coverage, adherence, and a variety of colors (black, yellow, brown, and gray) dependent on deposition temperature and film thickness. Growth rates were on the order of 1−2 μm min-1. All the films were crystalline. For substrate temperatures of up to 500 °C single phase films with the hexagonal SnS2 structure (a = 3.65(1) A, c = 5.88(1) A) were formed. At 525 °C a film of mixed composition containing predominantly orthorhombic Sn2S3 (a = 8.83(1) A, b = 3.76(1) A, c = 14.03(1) A) was formed together with some SnS2. At 545 °C films with orthorhombic SnS structure (a = 4.30(1) A, b = 11.20(1) A, c = 3.99(1) A) were formed. Scanning electron microscopy (SEM) revealed a variety of different film thicknesses and morphologies, including needles, plates, and ovoids, dependent on the deposition temperature and tim...

Semiconductor thin films by chemical bath deposition for solar energy related applications

Abstract: In this paper we present the basic concepts underlying the chemical bath deposition technique and the recipes developed in our laboratory during the past ten years for the deposition of good-quality thin films of CdS, CdSe, ZnS, ZnSe, PbS, SnS, Bi2S3, Bi2Se3, Sb2S3, CuS, CuSe, etc. Typical growth curves, and optical and electrical properties of these films are presented. The effect of annealing the films in air on their structure and composition and on the electrical properties is notable: CdS and ZnS films become conductive through a partial conversion to oxide phase; CdSe becomes photosensitive, SnS converts to SnO2, etc. The use of precipitates formed during deposition for screen printing and sintering, in polymer composites and as a source for vapor-phase deposition is presented. Some examples of the application of the films in solar energy related work are presented.

Simplified chemical deposition technique for good quality SnS thin films

Abstract: A chemical deposition technique, much simpler and more versatile than previously reported and capable of yielding good quality SnS films of thickness up to approximately=1.2 mu m under a choice of deposition conditions, is presented. The as-prepared films are polycrystalline with p-type dark conductivity in the range 10-5-10-4 Omega -1 cm-1 for the thicker ( approximately 1 mu m) films and showing a photocurrent to dark current ratio of 5-10 under 500 W m-2 tungsten halogen illumination. The optical transmittance and reflectance spectra and the photocurrent response curves of a series of SnS samples are explicitly presented to provide insight into possible applications of these films.

Chemical deposition of metal chalcogenide thin films

Abstract: Metal chalcogenide thin film preparation by chemical deposition is currently attracting considerable attention as it is relatively inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors or metals can be used since it is a low temperature process which avoids oxidation or corrosion of metallic substrates. It is a slow process which facilitates better orientation of crystallites with improved grain structure. Depending upon the deposition conditions, film growth can take place by ion-by-ion condensation of the materials on the substrates or by adsorption of the colloidal particles from the solution onto a substrate. Using this method thin films of groups II–VI, IV–VI, V–VI, I–III–VI etc. have been deposited. In this review article, the theoretical background of chemical deposition is described in detail. A survey of binary and ternary metal chalcogenide thin films is given with respect to their preparative parameters, structural, optical and electrical properties. Such films have been used in solar selective coatings, solar control photoconductors, solid state and photoelectrochemical solar cells.