PBX-002

Although nanoparticles of heavy metal xanthates and their hydrosols can play important roles in froth flotation, environmental issues, analytics, and manufacturing of metal sulfide nanocomposites, they have received little attention. We studied colloidal solutions and immobilized particles prepared via interaction of aqueous lead nitrate with alkyl xanthates applying UV-vis absorption spectroscopy, dynamic light scattering, zeta potential measurement, thermogravimetry analysis, Fourier transform infrared spectroscopy, Raman scattering, X-ray photoelectron spectroscopy, atomic force microscopy, and transmission electron microscopy. The hydrodynamic diameter of colloidal particles of Pb(SSCOR)₂ decreased from 500 to 50 nm with an increase in the alkyl radical length and the initial xanthate to lead ratio (X/Pb); the zeta potential magnitude varied similarly, although it remained negative. The effect of pH in the range of 4.5-11 was minor, but the colloids produced using excess of Pb²⁺ in alkaline media were close to PbX and decomposed much easier than PbX₂. The uptake of lead xanthates on supports was generally low because of negative charges of the colloids; however, 50-100 nm thick PbX₂ films were deposited on PbS and SiO₂ from the media of X/Pb < 2 and pH < 9 because of preadsorption of Pb²⁺, while nanorods formed on highly oriented pyrolytic graphite.

Doping of Mn²⁺ into semiconductor nanocrystals has been demonstrated to endow them with novel electronic, optical and magnetic functionalities. In this paper, Mn-doped CsPbX₃ (X = Br, Cl) quantum dots (QDs) were synthesized at room temperature via a facile strategy by introducing dimethyl sulfoxide (DMSO)-MnBr₂/PbX₂ composite as a precursor. The excitonic emission spectra of the as-obtained Mn-doped CsPbX₃ QDs can be tuned from 517 nm to 418 nm by adjusting the ratio of PbBr₂/PbCl₂ precisely, and the luminescence mechanism of the doped QDs is discussed in detail. Moreover, the highest photoluminescence quantum yield of the Mn²⁺ emission achieves 36.7%, which is comparable with QDs prepared by the conventional hot-injection method. Depending on the ratios of PbPb₂/PbCl₂, the energy transfer rate from the band-edge to Mn²⁺ excited state is in the range of 0.006-20.42 × 10⁷ s^-1. Furthermore, white light-emitting diodes (LEDs) were successfully fabricated by combining the as-prepared Mn-doped CsPbX₃ QDs with commercial UV GaN chips, and the high luminous efficiency of the as-prepared white LEDs was developed to 55.9 lm W^-1. This work strongly supports the fact that Mn-doped CsPbX₃ QDs are promising materials for application in lighting and displaying fields.