Advance Physics Letter ________________________________________________________________________________________________ ISSN (Print) : 2349-1094, ISSN (Online) : 2349-1108, Vol_1, Issue_2, 2014 59 Current Voltage (I-V) Characteristics of ZnS/PVK Nanocomposites Durgesh Nandini Nagwanshi Assistant Professor, Department of Applied Physics Jabalpur Engineering College, Jabalpur (M.P.) Email: dn.nagvanshi@jec-jabalpur.org, nandininagwanshi2525@gmail.com Abstract: ZnS/PVK nanocomposites have been successfully prepared by chemical method. The optical and electrical properties of nanomaterials can be controlled by their particle size and therefore attracted much interest for their fundamental and applied aspects. The size of the particle was varied with different ZnS loading. The XRD pattern showed that the ZnS nanoparticles has zinc blend structure and line broadening suggests the formation of amorphous compound. The broadening of peaks tends to increase with decreasing ZnS loading showing decrease in particle size. The crystalline size is found to be in range of 03 to 10 nm. Absorption measurements reveal blue shifting of absorption edge from bulk ZnS. V-I studies show the linear relationship between current and voltage which indicates the ohmic nature that is there is ohmic contact between samples and electrodes. The impedance decrease as we increase frequency of applied voltage. Keywords: - XRD, Absorption Spectra, ZnS, PVK. I. INTRODUCTION Poly N-vinyl carbazole (PVK) is a hole transport organic semiconducting polymer. It has been widely used as an electronic and optical material. ZnS is a well known inorganic and wide band semiconductor that has been a subject of considerable research due to its potential application in the areas of spin-electronics, opto-electronics, sensors, photocatalyst etc [1-4]. Previously, the nano composite of ZnS/PVK was prepared simply by mixing PVK and ZnS nano cluster or their precursors were prepared by simply mixing the synthesized nanoparticles with polymer. The effect of the inevitably introduced precursor molecules or the synthesized semiconductor nanoparticles is not clear to date, further more the conventionally synthesized semiconductor nanoparticles have a tendency to aggregate into larger clusters and their fine dispersion in the polymer is not very easy. Wang et al [5-7] has made a new approach for the preparation of truly two components ZnS/PVK nanocomposite. Khanna et al [8] have reported that the careful preparation of ZnS/CdS nanoparticles in DMF with metal rich surface can be considered responsible for stable light emission. This desire has promoted us to extend the synthetic methodology to functionalized and non- functionalized polymers. Polymers are considered a good choice as matrix materials for such purpose due to their long time stability and because they possess flexible reprocessibility. Present studies have been undertaken to synthesize ZnS/PVK nanocomposite with various loading of ZnS, characterize them by XRD, absorption spectra and investigated their I-V characteristics. II. EXPERIMENTAL For the synthesis of nanocomposite ZnS/PVK films, 400mg of poly N-vinyl carbazole (PVK) was dissolved in dimethylformaldehide (DMF) by constant stirring and heating at 80 o C temperature. Zinc acetate was added to the solution as 10, 20, 30 40 and 50% weight of PVK, so that ZnS loading in polymer equivalent weight. The resulting solution was stirred for 30 minutes. The solution was refluxed by applying nitrogen and then H 2 S gased for a 30 second. The solution immediately turned milky white. Now again the solution was stirred for a few seconds. The chemical reaction as follows: PVK + Zn(CH 3 COO) 2 + H 2 S ─> ZnS/PVK + 2CH 3 COOH Then the solutions were caste over glass slides and conducting glass plates and were dried in an oven for several hours to obtain uniform film of ZnS/PVK nanocomposite. The films on plane glass slides were characterized by using Bruker D8 advance X- Ray diffractometer at IUC Indore. Optical absorption studies were performed by Perkin Elemer spectrometer. For study of I-V charecteristics, nanocomposites of ZnS/PVK thin film sandwiched between conducting glass plate and thin film of aluminium foil. III. RESULTS AND DISCUSSION XRD: The ZnS/PVK nanocomposites were characterized by X–ray powder diffraction which showed on perfect match with the diffraction pattern in the literature [9]. The X- ray diffraction patterns of ZnS/PVK nanocomposites of different size are shown in figure (1). The ZnS/PVK nanocomposite, shows considerable broadening in the X – ray pattern. This broadening of the diffraction peak is primarily due to the finite size of the nanocrysrallites. The diffraction peaks found at 2θ approximately 17.46 0 , 28 0 , 48 0 and 56 0 . The