Environmental Engineering Reference
In-Depth Information
Figure 1.10
A schematic diagram of a PV solar cell based on a rectifying
Schottky contact and an ohmic back contact formed on an n-type
semiconductor, together with its energy band diagram.
The current-voltage (I-V) characteristics of a Schottky diode
under dark conditions can beexpressed by Eq. 1.2 [13, 14]:
exp
−
exp
eV
nkT
1
φ
b
kT
e
SA
∗
T
2
I
D
=
·
−
(1.2)
or
I
D
=
I
0
exp
eV
nkT
−
1
(1.4)
where
I
0
represents the saturation current.
For externally applied voltages across the diode above
∼
75 mV
(V
≥
75 mV):
exp
eV
nkT
1
(1.5)
Therefore, Eq. 1.4 can be simplified to the following form:
I
D
=
I
0
·
exp
eV
nkT
(1.6)
The rearrangement of this equation provides a useful relation to
analysetheI-VdatameasuredunderdarkconditionsforaPVdevice.
e
log
10
(
I
)
=
·
V
+
log
10
(
I
D
)
(1.7)
.
2
303
nkT
