Numerical Simulation And Performance Optimization Of Cu(In,Ga)Se2 Solar Cells

Abstract

Numerical simulation has been used to investigate the effect of the different layer components on the performance of CuInGaSe 2 solar cells. The effect of the gallium content in the Cu(In 1-x Ga x)Se 2 absorber and defect concentration in the CuInGaSe 2 absorber and in the CdS buffer layer as well as the effect of defects at the n-CdS/CIGS interface on the cell implementation has been analyzed using SCAPS-1D software. The main photovoltaic parameters of simulated devices: open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF), and conversion efficiency () were analyzed as a function of the defect density in the different layers. According to numerical simulation the highest conversion efficiency for CIGS solar cell is reached when the Ga content (Ga/Ga+In) in the CIGS absorber layer is about 30%. This result is validated by experimental results. When the defect density of CIGS absorber layer increases from de 10 12 cm -3 to 10 18 cm -3 , keeping constant the other parameters, the efficiency decreases by 83%. When the density of defects at the CdS/CIGS interface increases from 10 12 to 10 18 cm 2 , keeping constant the other parameters, both open circuit voltage and conversion efficiency also decrease but both parameters are less sensitive to interface defects than to absorber defects. This effect is related to recombination, which is more important when it takes place at absorber defects than at interface defects.