Modeling Effect of Defects on Efficiency of Nanowire CdS-CdTe Solar Cells

SCAPS simulation is conducted to model effect of defects on performance of the nanowire CdSCdTe solar cells. In the simulation model, acceptor type traps with a liner distribution of 1.05*10
¹⁸
/cm
³
and 6.0*10
¹⁷
/cm
³
are introduced in CdS nanowires. Donor traps with a liner distribution of 2.5*10
¹⁴
/cm
³
and 8.0*10
¹⁴
/cm
³
are presented in p-CdTe layer. Acceptor type interface states are tuned to 1.2*10
¹²
/cm
²
. The simulation models fit well with measured I-V, C-V and quantum efficiency characteristics of 12% nanowire solar cells. Simulation indicates that large energy bandgap in CdS layer reduces effects of defect traps of CdS layer on solar cell performance. In order to improve solar cell efficiency, it is necessary to search for approaches which increase shallow doping concentration and/or reduce donor trap concentration in the CdTe layer, and reduce interface states between CdS and CdTe.