الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Nano-semiconductors have many advantages making it an appealing choice for many applications. One of the most important nano-semiconductors is quantum dots which have attracted interests due to their unique size-dependent effect and their multiple exciton generation (MEG) effect.
The study is divided into three chapters:
Chapter one: Introduction and literature review: This Chapter includes a general introduction on semiconductor nanocrystals and quantum dots classification and its advantages which candidate it for using in many applications which one of them is solar energy application. A literature review on several types of quantum dots and their application in solar cells. Recent references related to research has been used.
Chapter two: This chapter deals with the two different experimental techniques that have been employed to prepare low cost environmental green water-soluble quantum dots such as: CdSe, CdTe, CdZnSe, CdZnTe, CdSeTe, CdZnSeTe and CuZnS core QDs with ZnS or CdS shells. One of these techniques is colloidal method. This technique has a disadvantage of weak attachment of QDs over TiO2 layer and this led to using of another technique to give a strong attachment which is hydrothermal method. This chapter studies the effect of capping agent and temperature on the size of quantum dots and band gap as well. Finally, it introduces the fabrication of quantum dots sensitized solar cells by using different types of TiO2 paste such as solaronix paste and prepared paste, counter electrode such as Platinum, CuxS and graphite electrodes and electrolyte such as polysulfide and poly-iodide electrolytes.
Chapter three: This chapter is composed into two parts: First one deals with the experimental results obtained from the structural, morphological and spectral characterization of quantum dots. In this part, we shows that, at high temperature, thioglycolic acid capping agent breaks down to give free sulfur which react with excess cations precursor present on the surface of prepared quantum dots to give QDs/cation-S core-shell. This shell acts as a protection layer for quantum dots from oxidation and thus it enhances the efficiency of quantum dots fabricated in solar cells. Structural characterization of QDs shows that all prepared quantum dots have zinc blende structure with agreement of the measured size with that obtained from morphological characterization. Also, it shows the bonding between quantum dots with TGA capping agent through sulfur atom present in TGA. The size obtained ensure the prepared semiconductors are prepared as quantum dots which have the size range (1-15 nm). Optical measurements of the prepared quantum dots show a shift in spectral curve due to the variety of band gaps obtained by varying the size of quantum dots.
Second part deals with the experimental results obtained from current- voltage characterization of quantum dots sensitized solar cell where poly-iodide electrolyte shows a corrosion property with
QDs which don’t exist in case of polysulfide electrolyte.