Free-standing nanocrystalline-Cadmium sulfide/Polyvinylidene fluoride composite thin film: synthesis and characterization

Nanocrystalline Cadmium sulfide (CdS) impregnated polyvinylidene fluoride (PVDF) composite free-standing flexible films were prepared by sol–gel technique. The films were poled in vacuum under high electric field. Effect of CdS loading in PVDF host matrix on the optical properties was studied critically for the as-deposited and poled samples. The reduction in the relative intensities of the peaks arising out of α -PVDF as compared to that of β-PVDF for the poled samples was observed in X-ray diffraction (XRD) studies. This type of observation indicates a possible transition from α to β phase due to poling. Modulation of optical and microstructural properties with CdS loading was also addressed. Bonding environment was studied by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy measurements. XPS studies indicated the presence of highly aligned CdS nanocrystallites in the poled PVDF matrix which may effectively modulate the piezoelectric behavior of the composite film. The Photoluminescence (PL) spectra recorded as above for a representative unpoled and poled nano-CdS/PVDF composite film.