Synthesis and optical properties of Mn²⁺-doped Cd–In–S colloidal nanocrystals

In recent years, light-emitting Mn²⁺-doped nanocrystals (NCs) have been widely studied because of their strong and stable Mn²⁺ d–d emission. Herein, highly efficient colloidal Mn²⁺-doped Cd–In–S NCs were prepared by a hot injection strategy. The as-prepared NCs have a cubic crystal structure of CdS host and exhibit strong Mn²⁺ emission. The photoluminescence (PL) intensity, PL position, and PL lifetime of this Mn²⁺ emission can be adjusted by changing the doping level of Mn²⁺. In particular, by tuning the amount of dopant, the emission color can be varied in the range of 601 nm to 643 nm, which is due to the coordination field environment of Mn²⁺ ions changed by the doping concentration. The PL intensity of Mn²⁺ is significantly enhanced by the ZnS shell coating, and the highest PL quantum yield can reach 56%, which is attributed to the removal of NCs surface-related defects by shell modification. A prototype LED was fabricated as well by using the as-prepared highly efficient Mn²⁺-doped Cd–In–S NCs as a color conversion material. The Mn²⁺-doped multicomponent semiconductor NCs reported here extend the availability of classical Mn²⁺-doped luminescent materials and provide alternatives for other applications requiring orange-red colloidal NCs.