A bright blue-shifted emission from Mn2+-doped CdS quantum dots

• The nucleation-doping strategy is hired for the synthesis of Mn2+-doped CdS QDs.
• We suggest Mn2+ ions are deeply doped into the QDs cores.
• The Mn2+-doped emission unusually appears at 563 nm rather than at 585 nm.
• Less energy level splitting of Mn2+ ions contributes to this blue shift.

In this letter, Mn2+-doped CdS quantum dots were successfully synthesized with stearic acid as the stabilizer by a nucleation-doping method. Generally, Mn2+-doped emission was at ~585 nm, which was well-established due to 6A1–4T1 transition of Mn2+ ions. Interestingly, a high-luminescence Mn2+-doped emission at ~563 nm was observed in the Mn2+-doped CdS nanocrystals. This large blue shift explained that Mn2+ ions were deeply doped in nanoparticle cores in our doping method, leading to less splitting of Mn2+ energy level. The results of transmission electron microscopy and X-ray diffraction also demonstrated the small particle size (~4.2 nm), monodispersity and high crystallinity. The quantum yield of the as-prepared nanocrystals was calculated ~41%.

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