A thermal failure model of solar cells and its experimental studies

Within silicon, silver is an impurity with fast diffusivity and deep levels. It forms effective recombination centres in silicon acting as either acceptor or donor levels. That has been confirmed by a depth-profile analysis with the SIMS. The silver atoms do exist near the barrier region of a solar cell with Ti/Pd/Ag electrodes heated at 245°C for 308 h. The open-circuit voltage at low injection decreases as recombination actions increase in the barrier region. According to these phenomena, an estimation for the lifetime of solar cells is given by using acceleration stress tests.