Bindu, K; Dr.Vijayakumar, K P(Cochin University of Science & Technology, May , 2002)
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Abstract:
In the present work, we describe our efforts to develop device quality
CuInSe2, films through low cost, simple and eco-friendly hybrid techniques. The
most important point to be highlighted here is that the method fully avoids the use
of poisonous gases such as H2Se/Se vapour. Instead, selenisation is achieved
through solid state reaction between amorphous selenium and polycrystalline
metal layers resulting in both binary and ternary selenides. Thin films of
amorphous selenium (a-Se) used for this is deposited using Chemical Bath
Deposition (CBD). CulnSe2 films are prepared through the selenisation process.
Another PV material, indium selenide (In2Se3) thin films are also prepared using
this process.
Description:
Department of Physics, Cochin University of
Science and Technology
Tina,Sebastian; Dr.Sudha Kartha,C; Dr.Vijayakumar, K P(Cochin University of Science & Technology, August , 2009)
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Abstract:
Aim of the present work was to automate CSP process, to deposit and
characterize CuInS2/In2S3 layers using this system and to fabricate devices using
these films.An automated spray system for the deposition of compound
semiconductor thin films was designed and developed so as to eliminate the manual
labour involved in spraying and facilitate standardization of the method. The system
was designed such that parameters like spray rate, movement of spray head, duration
of spray, temperature of substrate, pressure of carrier gas and height of the spray head
from the substrate could be varied. Using this system, binary, ternary as well as
quaternary films could be successfully deposited.The second part of the work deal with deposition and characterization of
CuInS2 and In2S3 layers respectively.In the case of CuInS2 absorbers, the effects of
different preparation conditions and post deposition treatments on the optoelectronic,
morphological and structural properties were investigated. It was observed
that preparation conditions and post deposition treatments played crucial role in controlling the properties of the films. The studies in this direction were useful in
understanding how the variation in spray parameters tailored the properties of the
absorber layer. These results were subsequently made use of in device fabrication
process.Effects of copper incorporation in
In2S3 films were investigated to find how the diffusion of Cu from CuInS2 to In2S3
will affect the properties at the junction. It was noticed that there was a regular
variation in the opto-electronic properties with increase in copper concentration.Devices were fabricated on ITO coated glass using CuInS2 as absorber and
In2S3 as buffer layer with silver as the top electrode. Stable devices could be
deposited over an area of 0.25 cm2, even though the efficiency obtained was not high.
Using manual spray system, we could achieve devices of area 0.01 cm2 only. Thus
automation helped in obtaining repeatable results over larger areas than those
obtained while using the manual unit. Silver diffusion on the cells before coating the
electrodes resulted in better collection of carriers.From this work it was seen CuInS2/In2S3 junction deposited through
automated spray process has potential to achieve high efficiencies.
Description:
Department of Physics,
Cochin University of Science and Technology
Varkey,K P; Dr.Vijayakumar, K P(COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY, August , 1999)
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Abstract:
The study on the fabrication and characterization of spray pyrolysed cadmium sulphide homojunction solar cells. As an alternative to the conventional energy source, the PV technology has to be improved. Study about the factors affecting the performance of the existing solar cells and this will result in the enhancement of efficiency of the cells. At the same time it is equally important to have R&D works on developing new photovoltaic devices and processes which are less expensive for large scale production. CdS is an important binary compound semiconductor, which is very useful in the field of photovoltaics. It is very easy to prepare large area CdS thin films. In order to fabricate thin film homojunction cadmium sulphide cells, prepared and characterized SnO2 thin film as the lower electrode, p-CdS as the active layer and n-CdS as window layer. Cadmium material used for the fabrication of homojunction solar cells is highly toxic. The major damage due to continued exposure to low levels of cadmium are on the kidneys, lungs and bones. The real advantage of spray pyrolysis process is that there is no emission of any toxic gases during the deposition. Very low concentration of the chemicals is needed in this process. The risk involved from this material is very low, though they are toxic. On large scale usage it may become necessary that the cells after their life, should be bought back by the companies to retrieve chemicals like cadmium. This will reduce environmental problem and also the material wastage
Urmila, K. S; Dr. Pradeep, B.(Cochin University of Science and Technology, August 6, 2016)
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Abstract:
The use of energy in our day to day life has grown exponentially and
conserving energy to meet the world’s escalating energy demands is the need of
the hour. During the past decade there is a heightened awareness all over the
world that the production costs of energy from coal, oil and natural gas is
increasingly higher and at the same time the energy technologies involving their
use are contributing to a serious rise in the greenhouse gases in the environment
and a consequent global warming. As a result, more attention is focused on the
utilization of clean energy technologies, especially solar energy which has a
great potential to meet a large fraction of world’s energy demands using
photovoltaics (PV). The heart of the PV system that efficiently convert sunlight
directly into electricity through photovoltaic effect is the solar cell - originally
developed for space applications in the 1950s, are now used in consumer
products, mounted on roofs of houses or assembled into large power stations.
Suma, C.S; Dr. Manoj, N.(Cochin University of Science and Technology, June 14, 2016)
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Abstract:
The thesis entitled “Photovoltaic and nonlinear optical studies of a few Donor-π-Acceptor molecules with s-triazine core” embodies the results of the investigations carried out to study unsymmetrically substituted s-Triazine cored starburst donor – acceptor systems with a bipodal acceptor/anchoring group design. The thesis opens with a review on the application of organic donor-acceptor systems in photovoltaics with special emphasis on applications in dye sensitised solar cells. The review also briefly discusses the application of such systems in the development of nonlinear optical materials.The unique structure of s-triazine do not permit direct coupling between the donor and acceptor moieties and this has been used as an effective tool for tuning HOMO and LUMO energy levels of such donor acceptor molecules. The effect of nature of the -bridge and the acceptor groups on the photovoltaic properties was studied and the results are presented in chapters 2, 3 and 4. Among the three types of -bridges studied, thiophene served as the best in terms of improving absorption spectral properties. Thiophene bridged dyes (DTT-CYA, DTT-RHA, DTT-BA and DTT-TBA) showed better coverage of the solar spectrum. Photovoltaic properties of these dyes were studied by constructing sandwhich model dye sensitized solar cells with nanocryasalline thin film of TiO2 on FTO coated with the respective dye as the photoanode, I-/I3- and Br-/Br3- as the redox couple/electrolyte and a platinized FTO as the cathode. The cell parameters and the photoconversion efficiency calculated show that the thiophene bridged dyes when used with Br-/Br3- as the redox couple/electrolyte have the optimal performance
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