Photoluminescence study of highly efficient CdTe thin film solar cells

Highly efficient CdTe thin film solar cells with a glass/CdS/CdTe/Cu-doped carbon/Ag structure, were characterized by low temperature photoluminescence (PL) measurement. A broad 1.42 eV band probably due to V/sub Cd/-Cl defect complexes appeared as a result of the CdCl/sub 2/ treatment. In the PL spectra of the heat-treated CdTe after the screen-printing of the Cu-doped carbon paste, a neutral-acceptor bound exciton (A/sub Cu//sup 0/, X) line at 1.590 eV was observed, suggesting that Cu atoms were incorporated into CdTe as effective accepters after the heat treatment. Furthermore, CdS/CdTe junction PL was measured, and two broad emissions at around 1.52 and 1.37 eV, lower than the PL peak energy in the CdTe surface, were observed. This result indicates that CdS/sub 1-x/Te/sub x/ mixed crystal layer was formed at the CdS/CdTe interface.