Environmental Engineering Reference
In-Depth Information
Figure 1.12
A schematic diagram of a Schottky barrier solar cell and its
equivalent circuit.
that the photo-generated current flows in the opposite direction to
the forward current under dark conditions. Therefore, the current
through the diode under illumination is given by
exp
eV
nkT
I
L
=
I
D
−
I
sc
=
I
0
·
−
I
sc
(1.11)
where
I
sc
denotestheshortcircuitcurrentproducedbythesolarcell
under illumination.
Figure 1.13
The direction of electron flow during forward bias under
dark conditions and when used as a solar cell device under illuminated
conditions.
TheI-VcharacteristicsdescribedbyEqs.1.6and1.11canthenbe
plottedinalinear-lineargraph,asshowninFig.1.14.Therearefour
important parameters to consider for a solar cell device.
•
Open circuit voltage (
V
oc
): This is the voltage measured when
the external circuit is in open condition, or when there is no
current flow in the external circuit.
