Cu migration and its impact on the metastable behavior of CdTe Solar Cells

In this work, we report on development of a 1D reaction-diffusion simulators of Cu kinetics in CdTe solar cells to investigate its role in the observed device performance changes. Evolution of intrinsic and Cu-related defects in CdTe solar cell has been studied in time-space domain self-consistently with free carrier transport. The simulation successfully predicted decelerating reductions of device performance for open-circuit stress and steadier reductions for short-circuit stress under elevated temperature in consistency with experiment findings. The simulation results indicated that the movement of Cu interstitials could be responsible for such changes. Although 1D simulation has intrinsic limitations when applied to poly-crystalline films, the results presented suggest strong potential of the approach in better understanding of the performance and metastabilities of CdTe photovoltaic device.