The impact of Cu on recombination in high voltage CdTe solar cells

Using photoluminescence spectroscopy, we construct a recombination model for state-of-the-art CdTe solar cells doped with Cu. We observe that Cu on Cd sites form a dominant acceptor state about 150 meV from the valence band. Although it is intuitive that this state can increase hole density, we also find that this relatively shallow dopant can also limit lifetime. Consequently, CdTe solar cells doped with Cu could have a lifetime limitation inversely proportional to the hole concentration.