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ghahary--raheleh
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Al doped ZnO NanoStructures by Electrodeposition & Solvothermal for Dye Sensitized Solar Cells Application
, M.Sc. Thesis Sharif University of Technology ; Taghavinia, Nima (Supervisor)
Abstract
ZnO semiconductor has a wide band gap (3.3eV) and high electron mobility, making it a possible candidate for an effective structure-based Dye-sensitized solar cell (DSSC) semiconductor. Efficiency of DSSC based on ZnO is lower than TiO2 due to its low chemical satability. It is well known that the energy conversion efficiency of DSSC depends on the electron transport in the photoelectrode so in this investigation we fabricated high transport photoelectrode by doping Al in ZnO nanostructures. DSSC based on Al doped and undoped ZnO nanosheet synthesized by electrochemical deposition. Current density-voltage (J-V) characterizations indicate that Al-doping in ZnO crystal structure increases...
Synthesis and characterization of new triphenylamine-based dyes with novel anchoring groups for dye-sensitized solar cell applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 28, Issue 2 , 2017 , Pages 1859-1868 ; 09574522 (ISSN) ; Hosseinzadeh, B ; Azari, M ; Ghahary, R ; Sharif University of Technology
Springer New York LLC
2017
Abstract
Three new chromophores based on the triphenylamine (MM, DM, DN) with various novel electron withdrawing anchoring groups have been synthesized for use in dye-sensitized solar cells (DSSCs). The sensitizers were characterized by 1H and 13C NMR, Mass, UV–Vis, and electrochemical analysis. The HOMO and LUMO electron distributions of the sensitizers were calculated using density functional theory on a B3LYP level for geometry optimization. The DSSC device based on DM dye showed the best photovoltaic performance among MM and DN dyes: maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 98 %, short circuit current (JSC) of 4.58 mA/cm2, open circuit voltage (VOC) of...
New organic dyes with diphenylamine core for dye-sensitized solar cells
, Article Journal of Materials Science: Materials in Electronics ; Volume 29, Issue 8 , April , 2018 , Pages 6323-6336 ; 09574522 (ISSN) ; Karami, M ; Hosseinzadeh, B ; Ghahary, R ; Sharif University of Technology
Springer New York LLC
2018
Abstract
In the current investigation, four novel donoracceptor type organic dyes including (DPA-Ba, DPA-Hy, DPA-Rh, DPA-Cy), are proposed and their photophysical and electrochemical properties as well as dye-sensitized solar cell performance are systematically investigated. Among these dyes diphenylamine is utilized as an-electron donor while barbituric acid, hydantoin, rhodanine-n-acetic acid and cyano acetic acid, are proposed as anchoring groups as dye-sensitized solar cells (DSSCs). The synthesized dyes are characterized using FT-IR, NMR, mass spectrometry, absorbance and electrochemical measurements. The photophysical, electrochemical and photovoltaic properties of the solar cells based on...
Fabrication of a Tactile Sensor Based on Triboelectric Nanogenerators
, Ph.D. Dissertation Sharif University of Technology ; Mohammadpour, Raheleh (Supervisor) ; Sasanpour, Pezhman (Supervisor)
Abstract
Humans need the five senses to understand and interact constructively with their surrounding environment; in the world of robots and intelligent systems, this is achieved using sensors. In the modern world, tactile sensors based on triboelectric effect play a prominent role in important application areas such as health monitoring, human-computer interaction, robotics, pressure mapping, and electronic signature. Triboelectric nanogenerators (TENGs) are one type of energy harvesting systems that convert mechanical energy into electrical energy. In these sensors, due to the contact and touch with the triboelectric material, an electric charge is generated and induced into the electrode, then...
Nanosheet arrays of TiO2synthesized by one step conversion of ZnO nanosheets: Boosting of electron transport rate and application in dye solar cells
, Article RSC Advances ; Vol. 4, issue. 85 , 2014 , pp. 45174-45179 ; ISSN: 20462069 ; Tajabadi, F ; Salehkoutahi, S. M ; Ghahary, R ; Taghavinia, N ; Sharif University of Technology
2014
Abstract
A TiO2replica of ZnO nanosheet films is synthesized using a chemical replacement process. ZnO nanosheets are grown by electrodeposition on fluorine doped tin oxide (FTO) films, and a dissolution/deposition process is used to convert the ZnO template into a TiO2replica. Electron microscopy shows the final TiO2structure follows the morphology of the initial ZnO template. X-ray diffraction and energy dispersive spectroscopy verify the total transformation of ZnO to TiO2. The as-synthesized TiO2sheets are amorphous and after annealing turn into the anatase phase. The film of TiO2nanosheets is used as the photoanode of a dye sensitized solar cell. Despite the low roughness factor of 100, a...
Novel organic dyes with anchoring group of barbituric/thiobarbituric acid and their application in dye-sensitized solar cells
, Article Synthetic Metals ; Volume 209 , November , 2015 , Pages 1-10 ; 03796779 (ISSN) ; Salimi Beni, A ; Najafi Chermahini, A ; Ghahary, R ; Teimouri, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Abstract New bi-anchoring donor-π-acceptor metal-free organic dyes based on diphenylamine as donor, and barbituric acid and thiobarbituric acid as the acceptor/anchor were synthesized, characterized and used in dye-sensitized solar cells applications. Among the fabricated dye sensitized solar cells, device based on the diphenylamine as donor, and barbituric acid as the acceptor exhibits a high power conversion efficiency of 1.53% with a short circuit current density of 3.71 mA cm-2, an open-circuit photo voltage of 0.55 V and a fill factor of 0.75% under AM 1.5 illumination (85 mW cm-2) compared to the other fabricated devices. The structure of synthesized dyes was optimized and their...
Design, synthesis and application of imidazole-based organic dyes in dye sensitized solar cells
, Article Journal of Electronic Materials ; Volume 49, Issue 6 , 2020 , Pages 3735-3750 ; Alinezhad, H ; Hosseinzadeh, B ; Ghahary, R ; Tajbakhsh, M ; Sharif University of Technology
Springer
2020
Abstract
Metal-free D–D–π–A type dyes (i.e., Car-Cy, Car-Rh, Dpa-Cy, and Dpa-Rh) were designed and synthesized for dye-sensitized solar cells (DSSCs). In the structure of the sensitized dyes, an imidazole ring is connected to a carbazole or diphenylamine moiety as a donor while cyanoacetic acid or rhodanine-3-acetic acid was introduced as an acceptor/anchor. The molecular structures of D–D–π–A type dyes were characterized using IR, NMR and MS spectral data. The optical, electrochemical, theoretical, light harvesting property, HOMO/LUMO levels, redox behavior, and photovoltaic properties of the synthesized dyes were evaluated. Among the fabricated photovoltaic devices based on the prepared dye, Dpa-Cy...
Fabrication of Nanostructure Cuprous Oxide Films for Photovoltaic Systems
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Metal oxide semiconductors are promising materials for photovoltaic systems, because they are chemically stable, almost non-toxic and abundant. These materials are cheap and have low cost fabrication process. Cu2O is the most popular metal oxide semiconductor to absorb light in Photovoltaic (PV) applications, and photocathode in the photoelectrochemical systems.In this project, thermal oxide and electrodeposition methods, both interesting and cheap, were applied for preparing Cu2O films. As inexpensive materials results in low-minority carrier diffusion length, we report on surface engineering of bulk Cu2O photocathode thorough employing nanorods of copper oxide with the average lengths of...
Synthesis and Characterization of 2D-WS2 Nanostructures for Gas Sensing Applications
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Nowadays, beside of two-dimensional tungsten disulfide nanosheets, its hybrid nanostructures also provide active sites for physisorption of gas molecules due to their high surface-to-volume ratio, surface active site (such as sulfur vacancies, surface defects, and p-n junctions) and active edges, and are very attractive for gas sensing applications. In this research, tungsten disulfide layered crystallines were grown by chemical vapor phase transport and its two-dimensional nanoflakes were prepared by liquid exfoliation method. So, a thin film of the nanoflakes was deposited on a silicon oxide substrate by drop casting method, and its gas sensing properties were investigated for water and...
Fabrication of gas ionization sensor based on titanium oxide nanotube arrays
, Article Applied Physics A ; Volume 115, Issue 4 , June , 2014 , pp 1387-1393 ; 1432-0630 ; Mohammadpour, R. (Raheleh) ; Iraji Zad, A. (Azam) ; Sharif University of Technology
2014
Abstract
Gas sensors have been fabricated based on field ionization from titanium oxide nanotubes grown on titanium foil. Ordered nanaotube arrays of titanium oxides were grown by the anodization method. We measured breakdown voltages and discharge currents of the device for various gases. Our gas ionization sensors (GIS) presented good sensitivity, selectivity, and short response time. The GISs based on TiO2 nanotube arrays showed lower breakdown voltage, higher discharge current, and good selectivity. An excellent response observed for Ar compared to other gases. Besides, by introducing 2 % CO and 4 % H2 to N2 flow gas, the amount of breakdown voltage shifts about 20 and 70 volts to the lower...
Fabrication and Characterization of Electron Transport and Buffer Layer Thin Films, Employing Sputtering Method, for All-Oxide Solar Cells
, M.Sc. Thesis Sharif University of Technology ; Iraji zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Co-Advisor)
Abstract
In this study, transparent conductive thin film of Aluminum doped ZnO (ZnO:Al) have been fabricated thorough RF sputtering. The main goal of fabrication of these layers is achieving thin films with minimum resistivity and maximum optical transparency in visible range of spectrum employing as transparent electrodes and buffer layer at the entirely oxidized solar cells. To achieve the suitable structure, various parameters including pressure, power and the thickness of the deposition and annealing on morphologies of thin film has been investigated. According to these results, thin film of ZnO:Al has the transparency of 80% in the visible light range . Doping of ZnO with Aluminum caused...
Investigation of the Ion Migration Mechanism and its Effect on the Slow Response of Perovskite Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
In recent years, organo-metal perovskite solar cells have attracted remarkable attention due to their low cost manufacturing method as well as the rapid growth of efficiency. Despite the fast growing efficiency of organo-metal perovskite solar cells, there are big challenges around their low stability under real operational condition. In addition to extrinsic parameters like oxygen and humidity, intrinsic instability of perovskite rises mainly from ion migration in perovskite film. In order to understand the ion migration and its effect on photovoltaic parameters of the devices, appropriate characterizations and analysis are needed. Since ions are much slower compare to electrons, their...
Modeling for Sensing Behavior of SnO2-CuO Nanostructures toward H2S Gas
, Ph.D. Dissertation Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Moosavi, Ali (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
H2S is a toxic and corrosive gas which is detrimental for both human’s health and some of important industries such as oil and gas. Based on different experimental research among various systems, resistive sensors fabricated from SnO2-CuO nanostructures have promising performance toward detection of this gas. High sensitivity and selectivity, response time of order of seconds, recovery times of order of tens of seconds and determining concentration of H2S gas below ppm level are advantages of this system. Unfortunately due to lack of a theoretical model, current experimental researches are excessively based on “trial and error” methodology. In this research some of the basic questions which...
Development of Modified Nanostructures for Fabrication of Polymer Nanocomposite Films for Controlled Atmosphere Food Packaging
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircherghi, Gholamreza (Supervisor) ; Mohammadpour, Raheleh (Co-Supervisor)
Abstract
Active packaging is a novel approach that can ensure food safety by removing undesirable compounds such as Oxygen, ethylene, moisture, and microbial contamination from fresh produce's environment and reducing product loss by extending shelf life. Current research on active food packaging materials focuses on using biopolymers such as carbohydrates, proteins, and lipids as alternatives to non-degradable petroleum-based packaging materials. Active nanomaterials are commonly used to impart functionality to packaging materials. However, the lack of functionality limits their industrial application.Therefore, the main objective of this work was to fabricate bioactive nanocomposite films by...
Molecular design of carbazole-based dyes and the influence of Alkyl substituent on the performance of dye-sensitized solar cells
, Article Molecular Crystals and Liquid Crystals ; Volume 629, Issue 1 , 2016 , Pages 29-43 ; 15421406 (ISSN) ; Zarandi, M ; Madram, A. R ; Bayat, Y ; Najafi Chermahini, A ; Ghahary, R ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
Carbazole is an alternant polycyclic aromatic hydrocarbon consisting of three fused rings with a large, aromatic system, containing nitrogen atom showing extensive electron delocalization. In this work, carbazole applied as π-conjugated bridge to construct electron donor–π–electron acceptor (D–π–A) organic dyes, where barbutiric acid and thiazolidine-2,4-dione as electron acceptor. The effects of these three acceptors and length of alkyl on the performance of the DSSCs were investigated systematically along with their photophysical and photo electrochemical properties. These series of organic dyes include (B-CH, B-C B, DT-CB, DB-CB). Our investigation indicate among dyes containing butyl as...
Printable Carbon Electrode for Perovskite & Thin Film Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Tajabadi, Fariba (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Solar cells, as a part of photovoltaics (PV) industry, have a significant share in the renewable energy market. Perovskite solar cells (PSCs) and thin film solar cells (TFSCs) achieved 23% and 22% power conversion efficiencies (PCEs) respectively. However, the PV industry still faces challenges like “high manufacturing costs” and “stability”. Among the strategies to overcome these challenges are substitution of the costly materials with cheaper, more abundant ingredients along with utilizing inexpensive deposition methods like printing rather than vacuum-based methods such as evaporation and sputtering. Carbon materials attract more attention in the solar cell research community for their...
Designing Electrophysiological Characterization System of Biological Cells Based on the Use of Nanostructured Electrodes
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Manouchehr (Supervisor) ; Sasanpour, Pezhman (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
In the last half century, the recording of the electrophysiological activities of the neurons has been one of the most effective methods for neuroscience development. One of the techniques used to record the activity of the nerve cells is the use of multi-electrode arrays (MEAs). Current MEAs still face limitations such as low signal-to-noise ratio (SNR) and low spatial resolution. There is a need to develop arrays that are smaller in size and have less impedance to achieve better spatial resolution and lower noise levels. The main focus of this research is on the designing and fabrication of multi-electrode arrays and improvement of their properties using nanostructures and conductive...
Using of SnS2 Nanostructured Layer as an Electron Transport Layer in the Perovskite Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Co-Supervisor)
Abstract
In this research, we focus on study and investigation of the role of Tin(IV) Sulfide (SnS2) nanostructured layer as electron transport layer in perovskite and chalcogenide thin film solar cells. For this purpose, SnS2 powder was prepared through hydro/solvo-thermal method, utilizing different ratios of water and ethanol as solvent and various sulfur sources (thioacetamide and thiourea). Afterwards, different solvents were investigated to achieve a stable ink (about one month) with uniform dispersion. After determining the appropriate ink and powder, thin films of SnS2 were prepared employing spin coating, spray pirolysis and laser pulsed deposition (PLD) methods and characterized. With each...
Study and Fabrication of Dye Sensitized Solar Cells Based on Nitrogen and Neodymium Doped Titanium Dioxide Photoelectrodes
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Co-Advisor) ; Taghavinia, Nima (Co-Advisor)
Abstract
In this thesis, we focus on studying and fabrication of doped titanium dioxide electrodes and their application in nanostructured dye sensitized solar cells (DSSCs). For this purpose, non-metallic nitrogen (N) and metallic neodymium (Nd) elements were selected. N-doped titanium dioxide nanoparticles were synthesized via solvothermal method and their structural and optoelectrical properties were investigated in comparison to undoped titanium dioxide synthesized by the same method. Based on the obtained results, doping of titanium dioxide by nitrogen resulted in shifting the Fermi level up-ward, increase in charge carriers density, shift of optical absorbance to higher wavelength, and decrease...
Fabrication of Triboelectric Nanogenerators based on Two-Dimensional Materials
, M.Sc. Thesis Sharif University of Technology ; Mohammadpour, Raheleh (Supervisor) ; Akhavan, Omid (Supervisor) ; Sasanpour, Pezhman (Supervisor) ; Shokrgozar, Mohammad Ali (Co-Supervisor)
Abstract
Triboelectric nanogenerator (TENG) works based on the accumulation of electrostatic charges produced on the surface of two dissimilar materials while they are brought into physical contact. When the surfaces are separated by a mechanical force, the induced triboelectric charges generate a potential drop, which can lead to generate an electrical current. Since their invention in 2012, TENGs have shown a rapid development in diversity of structure, amount of output power and range of applications, such as self-powered sensors, touch pads, and smart skin. Various kinds of mechanical force can be used for producing electrical energy: human motion, walking, vibration, rotating tire, wind, flowing...