Photoluminescence properties of transition metal-doped Zn-In-S/ZnS core/shell quantum dots in solid films

The photoluminescence (PL) properties of transition metal ion (Mn2+ or Cu+) doped Zn-In-S/ZnS core/shell quantum dots (QDs) in solution and solid films were investigated by using steady-state and time-resolved PL spectra. The PL peaks and lifetimes of Mn or Cu doped Zn-In-S/ZnS QD films exhibited almost no variation in contrast to those of the corresponding QD/PMMA blend films, indicating that no energy transfer process occurred in the pure doped QD films, while an obvious energy transfer was found in CdSe/ZnS QD films. Compared with the QDs in solution, the PL lifetimes of pure Mn or Cu doped Zn-In-S/ZnS QD films dropped only 16.2-37.5% which was attributed to the formation of surface traps/defects due to the loss of ligands on the surface of QDs while that of CdSe/ZnS QD films was shortened to the initial value of 50% which mainly came from energy transfer between QDs. Furthermore, the change in PL lifetimes found in Mn or Cu doped QD films could be reduced effectively by increasing the shell thickness of QDs. The experimental results are beneficial to the design of Mn or Cu doped QD-based photoelectronic devices.