Full Paper Optical properties ofcolloidal CdSe/CdS/Zns/PVPQDs core/ shellsembedded in fatty acid medium M.A.Batal, Kaesar Al-yamani* Department of Physics, College of Science, Aleppo University, (SYRIA) ABSTRACT Colloidal solutions of CdSewere prepared in fatty acidat room temperature. The prepared samples were coated with CdS, ZnS semiconductors shells. Absorption and fluorescencespectrum were measured. From absorption spectra the diameter of CdSe QDs and energy bandgap were calculated using hyperbolic approximation and some empirical equations. The diameter ofQDs were less than (2)nm and increase with ageing time reaching to 5 nm. CdSe QDs coated with moresemiconductors shells (CdSe/CdS,CdSe/ZnS, CdSe/CdS/ZnS) were prepared too. Also the system CdSe / CdS / ZnS / PVP[Core / shell / shell / shell] were prepared, that increase fluorescenceintensitywith more diluted by fatty acid. Finally, quantum confinement increase when the number of semiconductor shells increase.  2015 Trade Science Inc. - INDIA INTRODUCTION Cadmium selenide (CdSe) is solid hexagonal or cubic crystal. It belong to II-IV semiconductors and has direct band gap n-type semiconducting material with a band gap of 1.74 eV at 300K. Its molecular weight is 191.37 g/molWhere Cd is 58.74% and Se is 41.26%. Its appearance is dark red color [1] . The optical and electronic properties of CdSe QDs make it idealsemiconductors in many applications because its ability to control the diameters and itsenergybandgapin order to absorb and emit radia- tion of light. The most important applications of QDs are using in laser technology, Optical, electronics and medical treatment [2] . The differenceproperties of QDs. depend on the method of preparation. The strong quantum restriction of holes and electron raised optical and electronic properties, from those of bulk material [3] . Many studies have focused on the study III-V and II-VI groupsof semiconductor; CdSe belongs toII-VI group. The most common meth- ods of CdSeQDs.preparation are chemical method [4] . Many studies have focused on quantum yield,energy bandgap and diversity ofopto-electronic properties compared withCdSebulk materials [5] . In this study, high quality CdSeQDs was synthe- sized in fatty acid solutions. UV-VIS absorption, photoluminescence and fluorescence were carried out to characterize the optical properties of these QDs and to put in evidence the effect of organic and inorganic shell material quantum confinement. CALCULATION OF QDS CDSEDIAMETERS Tocalculate QDs diameter  s some empirical equations were used. The first one was found by [6] ,Itis a simple empirical relation between the CdSenanoparticle diameter and wavelength of ex- citon peak º(nm) as follow: ) 3 . 129 252 exp( 33 . 0 ) r 2 ( D    (1) An Indian Journal Volume 9 Issue 1 Nano Science and Nano Technology Nano Science and Nano Technology NSNTAIJ, 9(1), 2015 [022-028] ISSN : 0974 - 7494