Photoluminescence and thermal stability of Mn2+-doped CdSe/CdS/ZnS quantum dots

Colloidal Manganese-doped cadmium selenium quantum dots (Mn-doped CdSe QDs) and Mn-doped CdSe/CdS/ZnS core/multishell QDs were successfully synthesized via non-trioctylphosphine (non-TOP) green route. The TEM image reveals that the CdSe QDs are almost spherical in shape and have a good monodispersion. The optical properties of Mn-doped CdSe QDs were investigatedusing ultraviolet-visible and photoluminescence spectroscopy. The absorption spectra exhibit a red-shift with increasing QDs size, which is attributed to the quantum confinement effect. The PL spectra exhibit a first blue-shift to a later red-shiftwith increasing QDs size, which is attributed to the combined effect of Mn-doping and quantum confinement effect. Quantum confinement allows tuning of the CdSebandgap energy across the Mnexcited-state energies. Temperature-dependent (300–500 K) PL data suggest that Mn-doped CdSe/CdS/ZnS core/multishell QDs with enhanced thermal stabilities could be realized by blocking the nonradiative recombination centers with thick CdS/ZnS shells.