Photogeneration losses from interface trap density in Passivated Ultrathin CIGS Solar Cell

The present study investigates the effect of the interface defects for ultrathin Cu (In
1-x
Ga
x
) Se
2
solar cells using Silvaco TCAD. The initial simulation study is carried out with the reference cell configuration in which the PV parameters fit and match the fabricated cell characteristics. Our goal is to investigate the temperature dependence of the performance of u-CIGS solar cells in the temperature range of 10–70 °C and the loss mechanism caused by interface trap density (D
it
) in different cell pitch sizes on cell performance. D
it
defines the amount of carrier’s traps at CIGS/Al
2
O
3
interface to recombine with photogenerated carriers. The recombination mechanisms are found to play a crucial role in cell performance degradation. Further simulations quantify significant improvements in J
sc
and V
oc
for different cell pitch sizes at a fixed opening width in the Al
2
O
3
layer. Consequently, the optimum efficiency has been pointed out at a cell pitch size of 1.5 µm. MgF
2
has been used as an ARC layer to boost the efficiency up to 14 %. The results from these simulations provide insights for passivated u-CIGS solar cell optimization.