Structural and Nonlinear Optical Properties of Polymer Base CdS, Cus and, Ag2s Quantum Dots

Abstract

Synthesis of CdS, CuS and, Ag2S in the presence of PVA, as polymer stabilizer, was conducted by chemical bath way. The morphological studies followed by XRD (x-ray diffraction) and AFM (atomic force microscopy) revealed monolithic and small size quantum dots (QDs). The average size of QDs was 3.1, 3.2, and 3.4 nm average size for CdS, Ag2S, and, CuS, respectively. Uv-Vis absorption spectra of samples showed rutin behavior of decreasing absorption amount except CuS that had a minimum around 550 nm. The bandgap of samples was measured using absorption data is 4.3, 5.1 and, 5.2 (eV) for CdS, Ag2S and, CuS bandgap respectively. Nonlinear optical properties including nonlinear refractive index and nonlinear absorption of synthesized QDs were measured by Z-scan technique under 632.8 nm wavelength He_Ne CW laser. As we see from the figure.1, PVA/ Ag2S nanoparticles displayed reverse saturable absorber (RSA) and self-defocusing while PVA/CdS and PVA/CdS displayed saturable absorber and self-focusing behavior under the same condition. Concerning other similar researches [1-2], this work covered more vast types of nanoparticles and obtained and compared the differences.Figure.1. a)PVA/Ag2S, b)PVA/CdS, and c)PVA/CuS close aperture and d)PVA/Ag2S, e)PVA/CdS, and f)PVA/CuS open aperture date fitted by the theoretical function[1] Krishnakumar V, Shanmugam G, Nagalakshmi R. Large third-order optical nonlinearity of Mg-doped PbS/PVA freestanding nanocomposite films. Journal of Physics D: Applied Physics. 2012;45(16):165102.[2] Neo M, Venkatram N, Li G, Chin W, Wei J. Size-dependent optical nonlinearities and scattering properties of PbS nanoparticles. The Journal of Physical Chemistry C. 2009;113(44):19055-60. Figure 1