Aqueous synthesis of highly luminescent ternary alloyed Mn-doped ZnSeS quantum dots capped with 2-mercaptopropionic acid

Abstract

Highly photoluminescent and water dispersible ternary alloyed Mn-doped ZnSeS and core/shell Mn:ZnSeS/ZnS quantum dots (QDs) with pure dopant emission were synthesized through a simple aqueous route using thiolactic acid (2-MPA) as a capping ligand.Transmission electron microscopy and X-ray diffraction show that Mn:ZnSeS nanocrystals are of spherical shape, with a diameter of 2.4 nm and a cubic zinc blende structure. With the overcoating of the ZnS shell, the particle size increases to 3.7 nm, which confirms the epitaxial growth of the shell on Mn:ZnSeS cores. The photoluminescence (PL) quantum yield depends on the Mn loading and reaches 22% for Mn:ZnSeS cores doped with 10% Mn and 41% after the growth of ZnS at the surface of the cores due to the effective elimination of surface-trap states. Mn:ZnSeS QDs exhibit also long PL lifetimes (up to 681 μs) indicating that the emission originates from the spin forbidden Mn 2+ 4 T 1 → 6 A 1 transition. Electron paramagnetic resonance and X-ray photoelectron spectroscopy results suggest that Mn 2+ ions 2 are located at the interface of core/shell Mn:ZnSeS/ZnS QDs. Further, the stability of Mn:ZnSeS/ZnS QDs was also investigated along with their transfer in organic phase using octanethiol.

Binary temporary photo-response of ZnSe:Mn/ZnS quantum dots for visible time-domain anti-counterfeiting

“…When the ratio of Se : Zn exceeds 0.9, the PL spectra present a remarkable change as two different peaks appear: one, located at ∼380 nm, originates from the heterogeneity of the Se-rich surface states and relaxation of the vibrational states between the electronic excited and ground states, 38 and the other is the Mn 2+ emission at ∼580 nm from the 4 T 1 -6 A 1 transition. 39,40 Significantly, the PL intensity enhancement of the Mn 2+ transition with the increasing Se content illustrates that Se-rich content contributes to the Mn 2+ doping. Suffering from the lattice self-purification effect, 41 the doping of Mn 2+ into the ZnSe lattice will be inhibited in small QDs.…”

ZnSSe Decorated Reduced Graphene Oxide for Enhanced Photoelectric Properties

“…[12] Mabrouk et al synthesized 2-MPA-capped Mn:ZnSeS and Mn:ZnSeS/ZnS QDs, which possessed high quantum efficiency and photostability. [13] Chen et al synthesized quaternary/ternary alloyed CdZnSeS/ZnSeS QDs with excellent luminescence performance and thermal stability. [14] However, the DOI: 10.1002/ppsc.202300101 photoelectric properties of ZnSSe particles are limited due to their high surface energy, easy agglomeration of particles, and fast electron-hole pair recombination rate, which is similar to that of ZnS and ZnSe.…”

Aqueous synthesis of core/shell/shell ZnSeS/Cu:ZnS/ZnS quantum dots and their use as a probe for the selective photoluminescent detection of Pb2+ in water

“…Recently, the Cudoping of ZnS and ZnSe QDs has been investigated and it was demonstrated that the relaxation of the exciton occurs via the t2 energy states of Cu 2+ resulting in an emission in the green region valuable for applications such as bio-imaging, sensing, photocatalysis and light emitting devices [35][36][37][38][39][40][41][42][43][44][45][46][47][48]. Gradient alloyed ZnSeS QDs are well-known to exhibit improved optical properties and higher stability compared to binary ZnS or ZnSe QDs [49][50][51][52][53] but their doping with Cu has only scarcely been investigated [54,55]. Core/shell Cu-doped ZnSeS/ZnS QDs were prepared using the nucleation-doping method in which the Cu dopant is introduced at the earlier stage of the synthesis and thus located in the ZnSeS core [54,55].…”