And these three layers scribe processes. The only way to realign to each other.
So there's no lithographic patterning or anything going on over there.
Only way, these, these laser scribes are aligned are optical alignment.
And that essentially you know is, is requires you to leave
quite a bit of spacing between each of these label, laser scribes.
Essentially if I think about this region
which is in between these three laser scribe.
That essentially is the weight of this region, is typical
hundreds of micron in usual cells. Also
this, this region is not contributing to any solar energy conversion.
This is not essentially being. part of, a cell.
So this constitutes what is, the dead region, which
is called as often the dead region in my cell.
And its worth is denoted by I'm denoting over here by this symbol WD over here.
So, if you are a solar cell manufacturer, you
essentially, you want to minimize the fraction of this dead region.
So, let's say this is my dead region, and this is my actual cell.
So, I will minimize the fraction of this weight of the dead region.
Versus the rate of my cell.
So, essentially I want to minimize, I want to minimize or I want to
essentially minimize this fraction which is a WD by W.
So W would be you know fixed by
how precisely I can align these different scribe.
So essentially a way to reduce
this fraction would be to essentially maximize my, maximize my set rate.
So if I can make each of these cells very wide.
The contribution new to this dark region the no
contribution new to this dark region, it becomes insignificant.
But this poses another problem and the problem with the
large word of these thin film cell is that of I
squared R drop or the resistive drop across these these materials.
And let me explain that, let me explain that what does it mean.
So essentially these, these stairs are integrated using these accumulators
so the current would essentially be coming into this material here.
From the full arm, which are being absorbed.
They will essentially, you don't get connected in
this top TCO. And then they will assign for you don't go
and go again and the resist connection between this and the next cell.
But even this
[UNKNOWN]
this one
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this TCO material is placed on the top and it's If
series connected to the other cell using just this small small train over here.
The current as you can see is not uniform throughout this island at the top TCO this
[UNKNOWN]
over here
[UNKNOWN]
come in and
[INAUDIBLE]
the current over here.
But then in this region, these photons will again
come in over here, and contribute to the current.
And similarly you can see that the current inside this top TCO.
It's a growing or you know it's increasing as I'm moving from my left.
To the right.
So if I think of, my current, and I plot it as a function of, this direction x.
So my x, ix.
Or my current, inside this, inside this, TCO2.
It's increasing a linear lean as a function of x.
So if I think of this, in terms of our current density.
So let's, denote it. What this.
Current would be.
So I can think of this in terms of current
density and let's say I am operating at the maximum
power point then the current as a function
of x, it would essentially increase linearly as x.
And, this has to be multiplied by the total length of this, set.
So now, this is my current, through this,
through this, TCO region, and a function of x.
So what is the power loss? Due to this due to this current?
Is essentially
the I squared R loss in the cell. And let me write down over here.
So the power loss which is essentially associated
with the with this drop would be I
square, multiplied by the resistance so I can
express that in terms of the sheet resistance.
And I can, I need to now integrate it over, integrate it over this x.
So my x will now
vary from 0 to again w, which is the weight of this cell.
So I can substitute for this formula for ix from over here into this relationship.
So, I see my current it has a square my current has a linear relationship with x.
So my I squared would have a square relationship with x.
And when I when I
iterated or I'll get essentially a cubed relationship by terms of my rate.
So the, the total power loss would be essentially
this power which is a loss to over here.
when I integrated it would have essentially a one third term.
And then cubic dependence on the width of the cell.
And then these other terms
which is L squared term from here.
Which will divide by sorry, will leave a L term over here.
And then I have a sheet resistance term,
and a square of this maximum power current.
So this is my power which is essentially lost in the, in the,
due to this I squared, our loss. So what is the fraction of a power loss?
So essentially a fraction of the power lost
is essentially this by the power I produced.
And the power produced.
Is power produced.
I can express this in terms of my maximum power density.
Multiplied by multiplied by essentially my voltage
at which the maximum power is produced.
So if I do that essentially I'll get a
you know multiply it by multiply it by the total area of the cell.
So if I do that, the fraction of the power
loss due to this I square R drop, this fraction.
It comes out to be you know 1 3rd. Of my
1 3rd and then I have this current
the voltage
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and then squared them from, you know, this cube down divided by the step.
You leave this
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term uh,
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and this sheet rock g/ distance which you
know, which comes into play from over here.
So now essentially, you know, I have this fraction
which is a last due to the southern g/ region.
And then I have this fraction which allows you to do this I square I last.
So, I want to minimize the overall, I
want to minimize the overall loss of the power.
So, essentially the total power loss is
this power loss which happened due to net reason and this second term
over here which happened due to this I square R loss over here.
And you can clearly see that they have different dependences in the
vertices, so this first term is minimized when you have what large word.
So if w is large, this first term is minimized.
But the second term which is due to the R squared
are loss is minimized when you have other small, small word
[UNKNOWN].
When you have a small word you'll have
you know less current crowding, you'll have a less
square R drop. And that would minimise the second term.