Structural and optical studies of Zn1−xCdxS quantum dots synthesized by in situ technique in PVA matrix

Abstract

Zn1−xCdxS (x=0.1, 0.2, 0.3, 0.4, 0.5 … 0.9) quantum dots were synthesized successfully using novel in situ technique in polyvinyl alcohol (PVA) matrix. The PVA acted as a capping agent as well as a reducing agent. The structural and optical properties of the samples were studied by X-ray diffraction (XRD), TEM analysis, UV–Visible absorption and photoluminescence spectroscopy (PL). X-ray diffraction patterns revealed cubic zinc blende phase of the samples with lattice parameter in the range 5.47–5.75Å. Optical band gap values were calculated from the absorption spectra and observed a decreasing band gap with increasing Cd:Zn ratio. The Raman spectra were recorded using conventional Micro Raman technique. Photoluminescence spectra showed asymmetric broad emission with multiple maxima. The concentration dependent quenching of PL intensity with increasing Cd:Zn ratio was observed along with a red shift. The nonlinear optical (NLO) and limiting properties were studied using Z-scan technique.