Characterization of sns/cdxznl_xs thin film solar cell
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Date
2014-07-25
Authors
Ntabo, Edward Omuga
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Abstract
Semiconductors of group II-VI have potential applications in many technical fields,
including solar cells and photo voltaic applications. Photovoltaic cells grown on glass
substrates require p-type absorber thin films of optimum optoelectronic properties and ntype
wide band gap thin films. The control of the composition of Cd1_xZnxSmay lead to the
development of ideal materials for photovoltaic applications. Semiconducting Cd1_xZnxS
materials and related ternary compounds are promising materials for high density
optoelectronic applications. These applications are based on the structure of Cd1-xZnxS
which exhibit fundamental absorption edges that can be varied. In solar cell systems, where
CdS films have been demonstrated to be effective, the replacement of CdS with the higher
band gap Cd1_xZnxSalloys has led to a decrease in window absorption loss and an increase
in the short circuit current. In this research, zinc doped cadmium sulphide (CdxZnl_xS) thin
films will be prepared by Chemical Spray Pyrolysis (CSP) technique on glass substrates and
optimized. This will be done at different Zn doping percentages in CdS. On the other hand,
SnS absorber layer will also be deposited using CSP technique and optimized from aqueous
solutions on glass substrates. Samples of SnS will be prepared at different ratios and
substrate temperatures. The film's electrical properties (resistivity) will be measured using <,
the four point probe to determine their resistance. Optical properties like reflectance and
transmittance will be measured by UV-V[S - NIR 3700 spectrophotometer type and used to
calculate other optical properties like band gap (Eg) , refractive index (n), extinction
coefficient (k) and absorbance (a). The results will be analyzed to determine how optical
conductance, transmittance, absorbance and the electrical resistivity vary with the conditions
of deposition using the Scout software. Conditions that give Cdl-xZnxS and SnS optimum
optical properties will then be selected and used to fabricate a Cdl_xZnxS /SnS photovoltaic
cell expected to give the highest efficiency. The photovoltaic cell's performance
characteristics like short circuit current (Ise), open circuit voltage (Voe), fill factor (FF) and
conversion efficiency (11) will be calculated from I-V curve plotted using a solar cell
simulator.