Annealing temperature effects on the size and band gap of ZnS quantum dots fabricated by co-precipitation technique without capping agent

ZnS quantum dots (QDs) were fabricated using the co-precipitation technique with no capping agent. The effects of different annealing temperatures (non-annealed, 240 degrees C and 340 degrees C for 2 h) on the structural and optical characteristics of ZnS QDs are reported. The samples were examined by XRD, TEM, PL, FTIR, and UV-Vis. An increase in annealing temperature led to an increase in the dot size and a lowering of the energy band gap (E-G). The average crystallite size, D of ZnS was between 4.4 and 5.6 nm. The ZnS QDs showed a band gap of 3.75, 3.74 and 3.72 eV for non-annealed, 240 degrees C, and 340 degrees C annealed samples. The reflection spectra increased in the visible light and decreased in UV region with an increase in annealing temperature. This work showed that the band gap and size of ZnS QDs could be tuned by varying the annealing temperature.

Automated summary

ZnS quantum dots (QDs) were fabricated without a capping agent using the co-precipitation technique. The effects of different annealing temperatures (non-annealed, 240 degrees C and 340 degrees C for 2 h) on the structural and optical characteristics of ZnS QDs were investigated. The results showed that the annealing temperature influenced the dot size, energy band gap, and reflection spectra of the ZnS QDs.