الفهرس 
Chapter 1Only 14 pages are availabe for public view
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Abstract
The need for energy is growing, and the need for renewable, long-term energy sources is critical in order to transition away from fossil fuels. When compared to traditional energy sources such as fossil fuels, photovoltaic cells are more ecologically friendly. Traditional Si-based solar cells, on the other hand, have significant materials and fabrication costs, making solar energy more expensive than fossil fuels. Due to low-cost ingredients and simple production procedures, dye-sensitized solar cells (DSSCs) are frequently a cost-effective alternative to high-cost commercial Si solar cells. The DSC device is composed of a dye-sensitized mesoporous TiO2 or SnO2 electrode working as photoanode, iodide/triiodide ( ) redox electrolyte, and a Platinum-coated counter electrode. Under illumination, dye molecules attached to photoanode are excited from HOMO state to LUMO state. Instantly after, electrons in LUMO injected into the conduction band (C.B.) of the electron transport layer, which is commonly made of mesoporous TiO2 and discharged through the external circuit. Iodide ( ) ions in electrolyte regenerate the oxidized dye molecules with electrons and transforms to triiodide ions. Triiodide ions diffuse through electrolyte and get reduced by electrons at Pt/electrolyte interface to convert into ions to Complete the device working cycle. At TiO2/electrolyte interface, unfavorable recombination between electrons and ions occur. The latter reaction could be reduced by using additives into electrolyte to prevent such recombination. Here, we introduced aluminum
doped zinc oxide nanoparticles (AZO NPs) as an effective recombination suppressant additive in electrolyte of DSC to improve the overall power conversion efficiency of the device. The hypothesis of using AZO NPs is to adsorb anions in electrolyte ( ) away from TiO2 mesoporous surface and
reduce the probability of electron recombination with . The expected result is to enhance the open circuit voltage (VOC) and fill factor (FF) of solar cell device. If our hypothesis is true, ions also get adsorbed by AZO NPs which causes a lack in dye molecules regeneration with electrons indicated by lower short circuit current (JSC). To confirm this, we made measurements such as Open Circuit Voltage Decay, Mott-Schottky (MS), cyclic voltammetry, electrochemical impedance spectroscopy, UV-Vis absorption, Zeta potential measurements and Current density-voltage characteristics (J-V). from these measurements, we note that the best power conversion efficiency of the device at 0.1 wt.% of AZO NPs which was mixed in bulk electrolyte as shown in thesis.