M T S Nair

Bio: M T S Nair is an academic researcher. The author has contributed to research in topics: Thin film. The author has an hindex of 1, co-authored 1 publications receiving 94 citations.

PbS solar control coatings: safety, cost and optimisation

Abstract: Assessments of safety and cost and the optimisation of chemically deposited PbS thin films for solar control applications are presented. The maximum integrated infrared reflectance, 44%, is obtained at a PbS thin film thickness of approximately=95 nm. The corresponding value of the solar control parameters (AM2 case) are: integrated infrared transmittance, 45%; integrated visible transmittance, 17% (yellowish appearance); integrated visible reflectance, 21% (purple appearance); and integrated solar absorptance, 36%. The total solar radiation and heat transfer into the building through a glazing with such a PbS coating is less than 44%, as compared with the approximately=84% of 3 mm thick clear glass, giving a shading coefficient of approximately=50%. A film thickness of 95 nm is obtainable with a deposition time of 50 min from a bath (at 24 degrees C) containing Pb2+ ions and thiourea in the 1:3 molar ratio. However, molar ratios up to 1:5 may be employed, thereby enabling the reduction of deposition time to 35 min. Analyses of the safety and the cost of these coatings have shown excellent promise for their application as medium-efficiency low-cost solar control coatings appropriate for small-scale industrial and 'do-it-yourself' production of the coatings.

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.

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.

Structural and optical properties of PbS thin films obtained by chemical deposition

Abstract: Thin PbS films were chemically deposited on glass from alkaline baths containing lead nitrate, thiourea and different additions, such as hydroxylamine hydrochloride, triethanolamine or H 2 O 2 . The structural, optical and photoelectrical properties of these films were studied. The main characteristic of films as thick as 0.12–0.54 μ m is the photosensitivity. This parameter is influenced by many factors such as film thickness, grain and crystallite size, faults probability, number of layers, thermal treatment and the presence of impurities. Optical properties of these films were studied comparatively with those of some Au and Ni layers. The VIS. transmission and NIR reflection are comparable with those of the metallic films. The PbS films as thick as 21–62 nm can be applied for solar control coatings.