الفهرس 
POLYCRYSTALLINE SILICON FOR PHOTOVOLTAIC APPLICATIONS 1Only 14 pages are availabe for public view
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Abstract
ABSTRACT
To make the photovoltaic solar energy conversion economically
attractive,the cost of polysilicon solar cells
must be reduced to more than one order of magnitude below
the present cost of producing single crystal cells.
Silicon with higher concentration of impurities, so
called solar-grade silicon(SoG-Si), is the major candidate
to achieve this goal.
The different technologies to produce this solar-grade
silicon are discussed in detail besides the ether methods
for poly silicon production like· sheet casting or ribbon
technique ..
Grain boundaries and crystal defects are the main drawbacks
of polysilicon materials • l’he different models descriting
the conduction ];:Olysilic·on are also presented.
’:’l:e optical and
fabricated from
A n~merical ~otiel
cells is devolped .In
to have a cylinjrical
rotational axis, the
is reduced to a twG
rhe solar cell ou~~ut
the proposed motel. The r
properties of sclar cells
~aterials ar8 iescribed.
zing the polysilicon solar
, the grains are assumed
• Assutr:ing s~n~:metry a.bo;..lt the
:ontinuity eq~ation
one.
ts are analyzed and the
optimum design structures are then proposed • Furthermore,
b<::tsed on the at·ove CJ.entior.ed model, a new approach to the
ii
real polysilicon solar cell modeling is presented. In this
model, the real distribution of the grains in the polycrystalline
materials is taken into consideration • For the
first time,a quatitative agreement has been found between
measured and calculated results. More important, we have
deduced that the origin of the low open circuit voltage in
semicrystalline solar cells is the presence ot fine grains
taking the shape of sharp needles. In spite of the small
overall area of these small grains., they lower the opencircuit voltage of the cell and consequently its conversion
efficiency.