Luminescence of nanocrystalline ZnS:Cu2+

Abstract

Temperature dependent luminescence and luminescence lifetime measurements are reported for nanocrystalline ZnS:Cu 2+ particles. Based on the variation of the emission wavelength as a function of particle size (between 3.1 and 7.4 nm) and the low quenching temperature (T q ¼ 135 K), the green emission band is assigned to recombination of an electron in a shallow trap and Cu 2+ . The reduction in lifetime of the green emission (from 20 ms at 4 K to 0.5 ms at 300 K) follows the temperature quenching of the emission. In addition to the green luminescence, a red emission band, previously only reported for bulk ZnS:Cu 2+ , is observed. The red emission is assigned to recombination of a deeply trapped electron and Cu 2+ . The lifetime of the red emission is longer (about 40 ms at 4 K) and the quenching temperature is higher. r

White Light Emission from a Colloidal Mixture Containing ZnS Based Nanocrystals: ZnS, ZnS:Cu and ZnS:Mn

“…Increasing Cu concentration can push the t 2 level of Cu 2+ ions farther away from the valence band; therefore, the emission was significantly quenched when the dopant ion concentration reached over 2 at % against the ZnS host. In a particular case, red-orange light emission from the ZnS:Cu nanocrystal was reported by Bol et al; 33 however, we did not observe this phenomenon with our ZnS:Cu-MPA nanocrystal.…”

Cathodoluminescence Properties of SiO2: Ce3+,Tb3+, SiO2:Ce3+, Pr3+ and SiO2: PbS

“…This can only be possible if Pb 2+ ions are selectively excited. Note that blue, green and red emissions from Pb 2+ have been reported and the red emission, similar to the one in figure 20, was attributed to 3 P 0,1 → 1 S 0 transition of Pb 2+ (Bol and Meijerink, 2001). As shown in the inset of figure 20, the red-orange cathodoluminescence degraded by more than 50% following the prolonged irradiation by 2 keV electrons.…”

“…Therefore the orangered emission in figure 20 is neither coming from SiO 2 nor PbS nanoparticles. This emission is similar to emission associated with transitions in Pb 2+ ions in ZnS:Pb 2+ (Bol and Meijerink, 2001) and SiO 2 :Pb 2+ (Ntwaeaborwa et al, 2009b). Although the exact mechamism of this emission is not known yet, it is reasonable to attribute the emission to transisions in Pb 2+ .…”

Brilliant green dye added zinc(tris) thiourea sulphate monocrystal growth with enhanced crystalline perfection, optical, photoluminescence and mechanical properties

“…The grown crystals are belongs to high band gap materials category which makes them favorable applicant for optoelectronic device applications [38,[50][51][52]. and another violet-blue emission band at *420 nm (broad), which may be attributed to creation of S 2-vacancies due to dye doping as a results of vacancy sites and defect concentrations [53][54][55]. It is interesting to be noted here that the PL intensity of UV emission has been remarkably enhanced, which may be due to increase in vacancy related defects (F-centers) in the doped crystals that acts as color centers.…”