الفهرس 
Aim of workOnly 14 pages are availabe for public view
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Abstract
It is well known that energy consumption worldwide
heavily depends on fossil fuels, such as oil and coal.
However, the world has recognized that the supply of fossil
fuel is limited while the demand for fuel is still on the rise.
There is a pressing challenge to develop new types of clean
energy to provide our needs for energy consumption in the
future. The next generation of clean energy needs to be safe,
environmental friendly and low-cost. Among those, nuclear
energy, wind energy and solar energy have attracted
enormous research interests and have shown the most
potential in solving the current energy crisis. Solar cells can
be used for heating, lighting buildings, for generating
electricity and also for a variety of commercial and industrial
uses. So, in the present study, different nanomaterials were
prepared and the ability of these materials to enhance the
efficiency of solar cell, by increasing the time of
recombination between electron and holes, was studied. The
improvement of the solar cell efficiency by increasing the
light path in the active layer of the solar cell, as a result of
the development of these nanomaterials, was also
investigated. The study is divided into three chapters:
Summary and conclusion
101
Chapter one: This chapter represents the introduction to
the present work which includes a general background of the
global energy consumption and a brief description of
different types of solar cells and semiconductor metal
oxides, focusing on the description of ZnO and transition
metal oxides such as (TiO2, NiO and CuO) and the effect of
doping them on ZnO was also clarified. Also some of
research reviews published in advance in this field was listed
in this chapter.
Chapter two: This chapter includes the different
experimental techniques that have been used for
investigation the morphology, thermal and optical and
electrical properties of undoped and doped ZnO NPs such as
high-resolution transmission electron microscopy (HRTEM),
X-ray diffraction (XRD), thermal gravimetric
analysis (TGA), FT-IR spectra, Raman spectroscopy, UVdiffuse
reflectance (UV-DRS) spectrum and
photoluminescence (PL) spectra. (I-V) technique was used
to measure the efficiency of the DSSC cell at the different
studied preparation procedures.
Summary and conclusion
102
Chapter three: In this chapter, the experimental results
obtained from the structural, thermal, optical and electrical
measurements of undoped and doped ZnO nanoparticles
were analyzed. Morphological properties were investigated
by X-ray diffraction analysis (XRD), which reported poly
crystalline nature of the hexagonal wurtzite zinc oxide
structure according to JCPDS data (file: 01-080-4199), while
the success of doping process was confirmed by the
existence of new peak which appears at (200) plane
corresponding to secondary phase (TiO2, NiO and CuO).
XRD patterns also show that the optimum molar
concentration ratio of different metal oxide was (1.5 mol.
%) for NiO and CuO doped ZnO and (1.0 mol.% for TiO2
doped ZnO), these results were confirmed by HR-TEM and
SAED patterns which showed that optimum regular
spherical and uniform particle size distribution can be
achieved compared to the other molar ratios. The shifts in
stretching and bending modes at the FT-IR spectra and
Raman peaks were observed for doped samples compared to
undoped ones. UV spectra and PL spectra show some
modification in the absorption and band gap emission
respectively, which can be attributed to the improvement of
Summary and conclusion
103
separation recombination holes and electrons, this result
indicates that the enhancement of optical properties for
doped ZnO NPs is achieved. Current-voltage measurements
show enhancement of the efficiency of DSSC upon doping
with different metal oxides compared to pure ZnO NPs. By
analyzing the previous results, it can be concluded that
doping of ZnO with different studied metal oxides leads to
enhancement of the efficiency of DSSC from 1.26 ± 0.08 %
for DSSC based on ZnO to 3.15± 0.22 %, 3.01±0.25 % and
2.96±0.22 % for DSSC TiO2-ZnO, NiO-ZnO and CuO-ZnO
respectively, which makes it a very suitable candidate for
photovoltaic applications