ZnSe/ZnS:Mn core/(doped) shell and ZnSe/ZnS:Mn/ZnS core/(doped) shell/shell nanocrystals (NCs) that emit white light were synthesized in aqueous media. White light emission of as-prepared NCs is a result of combined emission of blue light (emission from band gap of ZnSe core) and yellow/orange light (⁴T₁–⁶A₁ emission from Mn²⁺ ions doped in ZnS of the first shell). Especially, the green emission generated from surface defects was found as a key factor that affects the photoluminescence quantum yields of core/(doped) shell and core/(doped) shell/shell NCs. Photoluminescence from the Mn:ZnS d-dots was easily tuned from 580–600 nm by regulating feeding molar ratio [Zn]/[Mn]. Under the sufficiently low Mn²⁺ dopant concentration, ZnSe/ZnS:Mn and ZnSe/ZnS:Mn/ZnS NCs emit white light with a quantum yield about 27.6% and 20.5%, respectively.

New water-soluble and highly luminescent ZnSe/ZnS:Mn/ZnS core/shell/shell nanocrystals with color-tunable emission range between 580 and 600 nm were synthesized via a three-step in single flask method.

Blue-emitting Ag⁽⁺⁾-, Cu⁽²⁺⁾-, and Mg⁽²⁺⁾-doped ZnSe nanoparticles (NPs) were successfully synthesized at 80 °C by the precipitation method by using mercaptopropionic acid (MPA) as a stabilizer. UV–visible and photoluminescence (PL) studies were applied to investigate their physicochemical properties. Their structural properties were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and transmission electron microscopy (TEM). The size of the ZnSe: X-capped MPA showed a strong relationship with dopant metals. The diameters of the Mg-doped ZnSe and the Cu-doped ZnSe were 22–24 nm, while the Ag-doped ZnSe was halved, at about 13 nm. The photoluminescence was within a wavelength range of 400–550 nm. In addition, the PL intensities, as well as the photoluminescence quantum yields, were in the order of the decreasing ionic radii of the dopant metals (ZnSe:Ag < ZnSe:Mg < ZnSe:Cu). Furthermore, through the interaction with lysine, the PL intensity of the ZnSe:X was changed. Interestingly, the capacity of the ZnSe:Mg for lysine was significantly higher than that of other dopant metals. Moreover, the toxicity of the ZnSe:Mg was relatively insignificant toward the hMSCs (about 80% cell viability at 320 ppm), compared to the transition-metal dopant. Therefore, the ZnSe:Mg material could have great potential for bioapplications.

Herein, the effect of three types of capping polymers, mercaptopropionic acid (MPA), polyethylene glycol (PEG), and starch on the photoluminescence of Mn(2+)-doped ZnSe (ZnSe:Mn) nanoparticles, has been investigated. ZnSe:Mn nanoparticles were successfully prepared with a green method of precipitation in aqueous solutions containing MPA, PEG, or starch as stabilizers. The X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy had proved the formation of ZnSe:Mn particles and the interaction between them and the capping agents. The resultant nanoparticles with different capping polymers were identical in optical property; however, photoluminescence quantum yields (PLQY) as well as the photoluminescence lifetime varied by capping agents. Starch-capped ZnSe:Mn nanoparticles had the biggest size compared to others, which was confirmed using transmission electron microscopy, dynamic light scattering, UV-Vis absorbance and Raman spectroscopy. Also, the PL intensity was significantly enhanced with starch-capped ZnSe:Mn nanoparticles. The PLQYs of starch archived 26%, which was 1.23 or 1.8 times lower than that of ZnSe:Mn nanoparticles capping with MPA or PEG, respectively. Furthermore, the highest decline of PL intensity was detected in PEG, which completely diminished in the 19th week, while both MPA and starch endowed ZnSe:Mn nanoparticles with outstanding PL lifetimes diminished over seven weeks.