Temperature dependence of the luminescence of nanocrystalline CdS/Mn2+

The temperature dependence of the luminescence properties of nanocrystalline CdS/Mn²⁺ particles is investigated. In addition to an orange Mn²⁺ emission around 585nm a red defect related emission around 700 nm is observed. The temperature quenching of both emissions is similar (T_q ≈ 100 K). For the defect emission the reduction in the lifetime follows the temperature dependence of the intensity. For the Mn²⁺ emission however, the intensity decreases more rapidly than the lifetime with increasing temperature. To explain these observations a model is proposed in which the Mn²⁺ ions are excited via an intermediate state involving shallowly trapped (≈ 40 meV) charge carriers.