Effects of Defects on Photovoltaic Solar Cell Characteristics - Advances in Thin-Film Solar Cells - page 175

twotypesofsolarcellsusedwere0.002cm 2 (0.5mmdiameter)and
0.090 cm 2 (3 × 3mm 2 ). The larger devices also had 120 nm thick
MgF 2 anti-reflection coating.
9.4.2 Instability of I-V Characteristics
A typical set of I-V characteristics for 3 × 3mm 2 solar cells is
shown in Fig. 9.5, and some measured parameters are summarised
in Table 9.2. The FF values of these devices are above 0.80, and the
highest measured V oc value is 1,150 mV. As shown in Fig. 9.5, the
I-V characteristics show excellent properties and these diodes were
selected for studying the effects of defects in solar cells when tested
after stressing from their equilibriumstate.
9.4.3 Application of Electrical Stresses to the Device
The devices selected were first measured for evaluation of their
solar cell parameters ( V oc , J sc , and FF), and then electrical stresses
were applied while the devices were kept at room temperature and
in dark conditions [9]. For example, the diodes were forward biased
with a voltage of ∼ 0.9 V for several hours and I-V curves were
Figure 9.5 I-V characteristics measured for two 3 × 3mm 2 solar cells
under air-mass 1.5 (AM1.5) conditions. Only one dark I-V curve is shown
for clarity, and the other curve is very similar. See also Colour Insert.