Synthesis and photoluminescence properties of Cl−-doped ZnS nanoparticles prepared by a solid-state reaction

• Emission of ZnS nanoparticles was increased remarkably by doping Cl.
• Annealing in air and vacuum enhanced the luminescence of ZnS:Cl nanoparticles.
• Emission of vacuum annealed sample was stronger than that of air annealed one.
• PVA helped to increase the emission intensity of ZnS:Cl nanoparticles.

ZnS:Cl− nanoparticles with strong blue emission have been synthesized successfully by a solid-state reaction at low temperature. The dependence of photoluminescence (PL) properties of ZnS:Cl− nanoparticles on the Cl− contents was researched, and the influences of the annealing ambience and using polyvinyl alcohol (PVA) during the synthesis on the PL of ZnS:Cl− (Cl/Zn = 0.35) nanoparticles were discussed. X-ray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy were used to characterize their structure, chemical state, diameter, surface states, and PL properties. The results showed that ZnS:Cl− nanoparticles had a cubic blende crystal structure and an average crystallite size of 17.40–19.16 nm. The most intensity blue emission peaking at about 425 nm was obtained when Cl/Zn = 0.35 under 330 nm excitation at room temperature. The emission intensity of ZnS:Cl− (Cl/Zn = 0.35) was increased 3-fold than that of ZnS. The results showed that the PL of ZnS:Cl− (Cl/Zn = 0.35) nanoparticles was enhanced after annealing or using PVA during the synthesis, and annealing in vacuum had a stronger effect in improving the luminescence properties of ZnS nanoparticles than in air. This work suggests that it is an effective method to improve the PL intensity of ZnS nanocrystals by doping with Cl− in ZnS.

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