i am adding ITO layer on crystalline silicon solar cell due to which my fill factor and short circuit current get decrease why this happen
Could you tell us how do you add the ITO layer to the c-Si solar cells and why do you add it?
From the principle point of view adding ITO as a conductive transparent layer has two effects:
Its transmission coefficient is less than one and thereby it attenuates the incident solar radiation causing direct reduction of the photocurrent and consequentially the short circuit current.
The other major effect that its conductivity is limited, it will impose resistance in the current path of the solar cell and hence decrease the fill factor as the fill factor decreases with the increase of the series resistance of the solar cell. There will be additional effects depending on how ito layer is built inside the solar cell.
Best wishes
Do you add the ITO to a standard silicon solar cell or a heterojunction?
For the later the following article might be of interest:
http://iopscience.iop.org/article/10.7567/JJAP.56.08MB17/pdf
sir Abdelhalim Zekry yeah u r right it is used as a transparent layer actually i just add this layer on HIT cell not physically but just add their work function which is 5.1 ev on top side and keep it 4.3 at back side but it decrease my fill factor and short circuit sir i not add it physically so how it increase the series resistance
Dear Naveed,
The hit cell consists of front ITO- p+ a Si- i a Si- n cSi- i aSi- n+ aSi- back metal. So, the ito layer serves as a transparent metal electrode contacting the p-type heavily doped amorphous silicon. Accordingly ito forms a heterojunction with the p+ aSi. In spite of heavy doping in both sides, which i hope yours is so, it may have an appreciable resistance. In addition as the currents flow laterally in the ito layer, it will resist the current flow adding series resistance to the solar cell.
So, my first comment is valid.
Best wishes
Dear Naveed
Following Prof. Zekry answer, when you insert a material (ITO) in the path of the charges i.e. between the two electrodes (top and bottom) you increase of course the series resistance and hence decrease the current. This increase the losses (as heat in the resistance) inside the Solar Cell (SC), beside the reduction of photons entering SC by ITO layer (15-20% light reduction).
Best wishes
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