LUMINESCENCE FROM THE AGGREGATED CU+ CENTERS IN SRSCU+

The photoluminescence (PL) and excitation spectra, PL decay curves and time-resolved PL spectra are measured at 80 K for the SrS:Cu+ powder phosphors activated with a large amount of Cu2S. The shape and peak position of the PL spectra depend on both the activator concentration and the excitation wavelength. The PL spectra consist of four kinds of Cu+ bands, alpha, beta, gamma and delta. The alpha band peaking at 513 nm at 80 K is attributed to the isolated Cu+ center, the beta band peaking at 543 nm at 80 K to the paired Cu+ center, and the gamma (558 nm at 80 K) and delta (about 600 nm at 80 K) bands to the highly aggregated Cu+ centers.