Meril, Mathew; Dr.Sudha Kartha,C(Cochin University of Science & Technology, January , 2009)
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Abstract:
In the present work, structural, optical and electrical properties of indium
sulfide are tuned by specific and controlled doping. Silver, tin, copper and chlorine
were used as the doping elements. In2S3 thin films for the present study were prepared
using a simple and low cost “Chemical Spray Pyrolysis (CSP)” technique. This
technique is adaptable for large-area deposition of thin films in any required shape and
facilitates easiness of doping and/or variation of atomic ratio. It involves spraying a
solution, usually aqueous, containing soluble salts of the constituents of the desired
compound onto a heated substrate. Doping process was optimized for different doping
concentrations. On optimizing doping conditions, we tuned the structural, optical and
electrical properties of indium sulfide thin films making them perform as an ideal
buffer layer.
Description:
Department of Physics,
Cochin University of Science and Technology
Rahana, Yoosuf; Dr.Jayaraj, M K(Cochin University of Science & Technology, October , 2007)
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Abstract:
Two stage processes consisting of precursor preparation by thermal
evaporation followed by chalcogenisation in the required atmosphere is
found to be a feasible technique for the PV materials such as n-Beta In2S3,
p-CulnSe2, p-CulnS2 and p-CuIn(Sel_xSx)2. The growth parameters such as
chalcogenisation temperature and duration of chalcogenisation etc have been
optimised in the present study.Single phase Beta-In2S3 thin films can be obtained by sulfurising the indium
films above 300°C for 45 minutes. Low sulfurisation temperatures required
prolonged annealing after the sulfurisation to obtain single phase Beta-1n2S3,
which resulted in high material loss. The maximum band gap of 2.58 eV was
obtained for the nearly stoichiometric Beta-In2S3 film which was sulfurised at
350°C. This wider band gap, n type Beta-In2S3 can be used as an alternative to
toxic CdS as window layer in photovoltaics .The systematic study on the structural optical and electrical properties of
CuInSe2 films by varying the process parameters such as the duration of
selenization and the selenization temperature led to the conclusion that for
the growth of single-phase CuInSe2, the optimum selenization temperature is
350°C and duration is 3 hours. The presence of some binary phases in films
for shorter selenization period and lower selenization temperature may be
due to the incomplete reaction and indium loss. Optical band gap energy of
1.05 eV obtained for the films under the optimum condition.In order to obtain a closer match to the solar spectrum it is desirable to
increase the band gap of the CulnSe2 by a few meV . Further research
works were carried out to produce graded band gap CuIn(Se,S)2 absorber
films by incorporation of sulfur into CuInSe2. It was observed that when the
CulnSe2 prepared by two stage process were post annealed in sulfur atmosphere, the sulfur may be occupying the interstitial positions or forming
a CuInS2 phase along with CuInSe2 phase. The sulfur treatment during the
selenization process OfCu11 ln9 precursors resulted in Culn (Se,S)2 thin films.
A band gap of 1.38 eV was obtained for the CuIn(Se,S)2.The optimised thin films n-beta 1n2S3, p-CulnSe2 and p-Culn(Sel-xSx)2 can be
used for fabrication of polycrystalline solar cells.
Description:
Department of Physics,
Cochin University of Science and Technology
Teny Theresa, John; Dr.Vijayakumar, K P(Cochin University of Science and Technology, December , 2004)
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Abstract:
As emphasis towards sustainable and Renewable energy resources grows world-wide,interest in the capture and use of solar energy is increasing dramatically.Solar cells have been known and used for many years,but depletion of conventional energy resources resulted in the intensification of research on solar cells leading to new design and technique of fabrication.The current emphasis is directed towards high effiency inexpensive solar cells.This thesis includes deposition and characterization of CuInS2 and In2S3 thin films using chemical Spray Pyrolysis(CSP) technique.The optimum condition for these films to be used as absorber and buffer layer respectively in solar cells were thus found out.Solar cell with the stucture,ITO/CuInS2/In2S3/metal electrode was fabricated using these well-characterized films,which yielded an efficiency of 9.5%.
Description:
Department of Physics,
Cochin University of Science and Technology