Numerical optimization of ultrathin CIGS solar cells with rear surface passivation

Abstract

We use Silvaco-TCAD tools to optimize ultrathin Cu (In1-xGax) Se2 solar cells with rear surface passivation. First of all, the single CIGS structure was performed and calibrated with the electrical and optical output of the experimental results. Based on the simulation and example results, considering the variety of carrier’s transport mechanism at the heterointerface CdS/CIGS shows a significant impact on cell performance. The proposed rear passivated ultrathin CIGS structure consists the following configuration: MgF2 (120 nm)/ZnO:Al (300 nm)/ZnO(100 nm)/CdS(50 nm)/CIGS(500 nm)/Al2O3/Ag/glass-substrate. The effect of the rear-passivated, absorber thickness (CIGS), and cell pitch on ultrathin CIGS cell performance is analyzed and studied under AM 1.5G, 1 sun illumination. This increases the model’s total implied photocurrent density from 21.1 to 29.1 mA/cm2. The simulations show that the ultrathin CIGS cell efficiencies of up to 13% can be obtained. The results from these simulations are compared with the measured characteristics of the fabricated cell.