الفهرس 
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Abstract
This thesis introduces modeling and analysis of solar cells and then focusing on
the tandem solar cells. Tandem solar cell types and operation concept are given with its advantages
and limitations. This thesis focusses on two terminal tandem solar cells. The design and results of
testing four different top (Perovskite) sub-cells and four bottom sub-cells are given. The four top
sub-cells are: perovskite (MAPbI3), perovskite (MAPbI3-xClx), carbon perovskite (MAPbI3), and
electron transport layer free perovskite (MAPbI3-xClx). After those four bottom sub-cells were
introduced based on using silicon, copper indium gallium selenide, germanium telluride, and two
absorber sub-layers using both copper indium gallium selenide and germanium telluride materials
with different doping levels to improve the voltage of the cell. It shows a good result as it is
equivalent electrically to two seirsly connected, this shows a higher voltage and better
performance. The two absorbers bottom sub-cell; have a limitation of current as the sub-layer with
the minimum current density limits the sub-cell and in turn the tandem cell current density. Then
a proposed solution of the current limitations of the two terminal tandem solar cells (current density
must be the same of both sub-cells) is introduced based on using germanium telluride. As the
bottom sub-cell is always the one with minimum current density that limits the overall tandem
current density and the tandem cell efficiency. Germanium telluride bottom sub-cell shows a high
current density which allows the top sub-cell to operate at a high current density value and in turn
the tandem cell, this improves the tandem cell efficiency. Through this thesis sixteen different
tandem cells were designed and tested. A new algorithm of optimizing the top sub-cell absorber
layer is proposed. Also, a study of the tandem cell performance stability with temperature
variations in the range (260°K to 360°K) is introduced. The designed tandem cells show different
performance parameters with a promising result up to about 45% power conversion efficiency.