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    Preparation and Characterization of Sol-Gel Derived Mesoporous TiO2 Nanostructured by Copolymer Templated

    , M.Sc. Thesis Sharif University of Technology Mozaffari, Naeimeh (Author) ; Mohammadi, Mohammad Reza (Supervisor) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Abstract
    In recent years, mesoporous nanocrystalline TiO2 films have been regarded extensively. This kind of materials due to having unique surface area, structural and bulk properties, is used in many technological applications. In this work, a stable TiO2 sol was prepared using F127 Copolymer template and evaporation induced self-assembly method (EISA). The mesoporous TiO2 powders and thin films were then prepared. The as-deposited thin films were aged under five different conditions for 72h. Finally the samples were heat treated at 350°C, 400°C and 450°C. N2 adsorption/desorption results verified formation of mesoporous structure. Moreover, x-Ray diffraction patterns exhibited that the synthesized... 

    Light Induced Curing of TiO2 Mesoporous Layer Utilized in Perovskite Solar Cells

    , M.Sc. Thesis Sharif University of Technology Zamanpour, Fahimeh (Author) ; Taghavinia, Nima (Supervisor)
    Abstract
    The efficiencies of perovskite solar cells have increased rapidly in recent years and reached about 22%. Which hopes to make this type of solar cell more functional. In the normal structure of perovskite solar cells, the presence of mesoporous TiO2 mesoporous layer has increased sustainability and efficiency. To create this layer, a common method is placing the sample in a furnace for 30 minutes at 450°C-500°C. Using the furnace, in addition to being time consuming, has a high energy consumption. In this study, we tried to create a TiO2 mesoporous layer with the help of lighting. To create TiO2 mesoporous layer, What causes porosity in the layer is the removal of ethyl cellulose and create... 

    Deposition of CdS on Nanostructured and Mesoporous TiO2 Film for Solar Cell Application

    , M.Sc. Thesis Sharif University of Technology Moayeri, Vahid (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Abstract
    In this project, The cadmium sulfide nanoparticles were formed on a nanostructured and meso-porous titanium dioxide layer and its properties were characterized. Deposition process of titanium dioxide and cadmium sulfide has been performed respectively in one stage and two stages of dipcoating. In order to probing effects of temperature and dipcoating time, samples have been prepared in various times and temperatures. Also, some of the samples have been annealed. Thickness of titanium dioxide and cadmium sulfide coatings were approximately measured 1 μm and between 3-5 μm, respectively. As expected, XRD results disclosed that cadmium sulfide and titanium dioxide were formed in the form of... 

    Gel-Electrolyte Based Dye-Sensitized Solar Cell Employing Mesoporous Tio2 Beads

    , M.Sc. Thesis Sharif University of Technology Mohsenzadegan, Nima (Author) ; Askarim, Masoud (Supervisor) ; Mohammadi, Mohammad Reza (Co-Supervisor)
    Abstract
    Nowadays, dye-sensitized solar cells (DSSCs) are highly regarded as a cheap alternative for conventional silicon-based solar cells. Improvements of their efficiency and performance sustainability are two major challenges of their commercialization. Engineering of the photoanode electrode by controlling its thickness, chemical composition, and morphology was proposed as effective method in increasing the light conversion efficiency of the cells. In the present study, mesoporous TiO2 beads with different arrangements including pristine mesoporous beads, mixtures of mesoporous beads with nanoparticles, and in the form of two-layer structure of nanoparticles (as an active layer) and mesoporous... 

    Stability Enhancing of Perovskite Solar Cell by Replacing TiO2 Mesoporous Layer with Oxide Perovskite Structures

    , M.Sc. Thesis Sharif University of Technology Saremi, Fatemeh (Author) ; Mohammadi, Mohammad Reza (Supervisor) ; Seyed Reihani, Morteza (Supervisor)
    Abstract
    The purpose of this study is fabrication and characterization of a mesoporous Perovskite solar cell using Barium Titanate as the mesoporous electron transfer layer. In this study, TiO2 nanoparticles and BaTiO3 oxide perovskites were prepared by sol-gel synthesis method and their pastes were applied to the conductive substrate by spin coating method and applied to electron transfer layer in perovskite solar cells. Then Perovskite solar cells were fabricated with different structures from the electron transfer layer.The results of X-ray diffraction analysis showed that pure Barium Titanate and Titanium dioxide nanoparticles were successfully synthesized with tetragonal and cubic crystal... 

    Enhanced Electronic Properties in Mesoporous TiO2 Via Passivation Treatment in Perovskite Solar Cells

    , M.Sc. Thesis Sharif University of Technology Azadi, Moloud (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Abstract
    Perovskite solar cells are the new generation of solar cells, and are mainly introduced in two types of structures.1) planer and 2) mesoscopic structure. The difference between these two structures derives from the absence of mesoporous layer in the planer structures. The mesoporous layer acts as an electron transporting layer, and is mainly a titanium dioxide semiconductor. To apply the mesoporous layer, the preparation of the TiO2 paste is needed.The synthesis of titanium dioxide nanopowder for the preparation of TiO2 paste requires high temperature heat treatment and is not desirable in terms of energy consumption.Another weakness of this layer is the presence of surface defects, which... 

    Synthesis and Evalouation of photovoltaic Properties of Lead-halid Perovskite

    , M.Sc. Thesis Sharif University of Technology Nejadsalim, Aidin (Author) ; Simchi, Abdolreza (Supervisor) ; Ashouri, Hossein (Supervisor)
    Abstract
    Organometal lead halides due to their interesting optical properties and convenient synthesis processing have attracted many attention recently. In this project, fabrication of lead halide perovskite solar cells through one-step deposition and two-step deposition with different holding time of PbI2 layers in various concentration of CH3NH3I solution as a second precursor within the ambient and glove box atmosphere has been studied. Structural, microscopic and photovoltaic properties of fabricated solar cells were evaluated. Moreover effect of delay time during PbI2 deposition on TiO2 mesoporous layer in performance of perovskite solar cell using Energy Dispersive Spectroscopy was studied.... 

    Origin of apparent light-enhanced and negative capacitance in perovskite solar cells

    , Article Nature Communications ; Volume 10, Issue 1 , 2019 ; 20411723 (ISSN) Ebadi, F ; Taghavinia, N ; Mohammadpour, R ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
    Nature Publishing Group  2019
    Abstract
    So-called negative capacitance seems to remain an obscure feature in the analysis of the frequency-dependent impedance of perovskite solar cells. It belongs to one of the puzzling peculiarities arising from the mixed ionic-electronic conductivity of this class of semiconductor. Here we show that apparently high capacitances in general (positive and negative) are not related to any capacitive feature in the sense of a corresponding charge accumulation. Instead, they are a natural consequence of slow transients mainly in forward current of the diode upon ion displacement when changing voltage. The transient current leads to a positive or negative ‘capacitance’ dependent on the sign of its...