Luminescence of nanocrystalline ZnS:Cu2+

\u3cp\u3eTemperature dependent luminescence and luminescence lifetime measurements are reported for nanocrystalline ZnS:Cu\u3csup\u3e2+\u3c/sup\u3e 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\u3csub\u3eq\u3c/sub\u3e = 135 K), the green emission band is assigned to recombination of an electron in a shallow trap and Cu\u3csup\u3e2+\u3c/sup\u3e. The reduction in lifetime of the green emission (from 20 μs at 4 K to 0.5 μs 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\u3csup\u3e2+\u3c/sup\u3e, is observed. The red emission is assigned to recombination of a deeply trapped electron and Cu\u3csup\u3e2+\u3c/sup\u3e. The lifetime of the red emission is longer (about 40 μs at 4 K) and the quenching temperature is higher.\u3c/p\u3

Temperature dependence of the luminescence of nanocrystalline CdS/Mn2+

\u3cp\u3eThe temperature dependence of the luminescence properties of nanocrystalline CdS/Mn\u3csup\u3e2+\u3c/sup\u3e particles is investigated. In addition to an orange Mn\u3csup\u3e2+\u3c/sup\u3e emission around 585nm a red defect related emission around 700 nm is observed. The temperature quenching of both emissions is similar (T\u3csub\u3eq\u3c/sub\u3e ≈ 100 K). For the defect emission the reduction in the lifetime follows the temperature dependence of the intensity. For the Mn\u3csup\u3e2+\u3c/sup\u3e emission however, the intensity decreases more rapidly than the lifetime with increasing temperature. To explain these observations a model is proposed in which the Mn\u3csup\u3e2+\u3c/sup\u3e ions are excited via an intermediate state involving shallowly trapped (≈ 40 meV) charge carriers.\u3c/p\u3