Loading...
Search for: tavakoli--m--r
0.182 seconds

    Multilayer evaporation of MAFAPbI3-xClx for the fabrication of efficient and large-scale device perovskite solar cells

    , Article Journal of Physics D: Applied Physics ; Volume 52, Issue 3 , 2019 ; 00223727 (ISSN) Tavakoli, M. M ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Saliba, M ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    FAPbI3 perovskites are excellent candidates for fabrication of perovskite solar cells (PSCs) with high efficiency and stability. However, these perovskites exhibit phase instability problem at room temperature. In this work, to address this challenge we use methylammonium chloride (MACl) as an additive and employed a layer-by-layer thermal evaporation technique to fabricate high-quality perovskite films on a large scale of 25 cm2. The optimized perovskite films show high crystallinity with large grains in the μm-range and reveals phase stability due to the presence of MACl after the annealing process. Finally, we achieved PSCs with 17.7% and 15.9% for active areas of 0.1 cm2 and 0.8 cm2,... 

    Organic halides and nanocone plastic structures enhance the energy conversion efficiency and self-cleaning ability of colloidal quantum dot photovoltaic devices

    , Article Journal of Physical Chemistry C ; Volume 121, Issue 18 , 2017 , Pages 9757-9765 ; 19327447 (ISSN) Tavakoli, M. M ; Simchi, A ; Tavakoli, R ; Fan, Z ; Sharif University of Technology
    American Chemical Society  2017
    Abstract
    This paper presents solid-state ligand exchange of spin-coated colloidal lead sulfide quantum dot (PbS QD) films by methylammonium iodide (MAI) and integration of them in depleted heterojunction solar (DHS) devices having an antireflecting (AR) nanocone plastic structure. Time-resolved photoluminescence measurements determine a shorter lifetime of the charge carries on a semiconductor (TiO2) electron transfer layer for the MAI-passivated QD films as compared with those with long-chain aliphatic or short thiol ligands. Consequently, the DHS device yields improved power conversion efficiency (>125%) relative to oleic-acid-passivated PbS QD films. Using anodized aluminum oxide templates, an... 

    Surface engineering of TiO2 ETL for highly efficient and hysteresis-less planar perovskite solar cell (21.4%) with enhanced open-circuit voltage and stability

    , Article Advanced Energy Materials ; Volume 8, Issue 23 , 2018 ; 16146832 (ISSN) Tavakoli, M. M ; Yadav, P ; Tavakoli, R ; Kong, J ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Abstract
    Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high-performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a-SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double-layer structure of TiO2 compact layer (c-TiO2) and a-SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a-SnO2/c-TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c-TiO2 based device.... 

    Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing.Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing

    , Article Solar RRL ; 2020 Tavakoli, M. M ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    The fabrication of efficient perovskite solar cells (PSCs) using all-vacuum processing is still challenging due to the limitations in the vacuum deposition of the hole transporting layer (HTL). Herein, inverted PSCs using copper (II) phthalocyanine (CuPC) as an ideal alternative HTL for vacuum processing are fabricated. After proper optimization, a PSC with a power conversion efficiency (PCE) of 20.3% is achieved, which is much better than the PCEs (16.8%) of devices with solution-based CuPC. As it takes a long time to dissolve CuPC in the solution-based device, the evaporation approach has better advantage in terms of fast processing. In addition, the device with the evaporated CuPC HTL... 

    Efficient perovskite solar cells based on Cdse/Zns quantum dots electron transporting layer with superior UV stability

    , Article Physica Status Solidi - Rapid Research Letters ; Volume 14, Issue 6 , 2020 Tavakoli, M. M ; Prochowicz, D ; Yadav, P ; Tavakoli, R ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    Stability is the main challenge in the field of perovskite solar cells (PSCs). Finding new strategies is required to protect the PSCs from deteriorating agents such as humidity, heating, and illumination. Herein, a new electron transporting layer (ETL), i.e., CdSe/ZnS quantum dots (QDs), is proposed for the fabrication of efficient and stable PSCs. CdSe/ZnS QDs layer not only works as an ETL but also has downshifting property, which can improve both efficiency and stability of the PSCs. Using CdSe/ZnS QDs ETL with green emission, a PSC with maximum power conversion efficiency (PCE) of 18% is achieved. More importantly, the device shows great UV stability, much better than the device with... 

    Oxygen plasma-induced p-type doping improves performance and stability of PbS quantum dot solar cells

    , Article ACS Applied Materials and Interfaces ; Volume 11, Issue 29 , 2019 , Pages 26047-26052 ; 19448244 (ISSN) Tavakoli Dastjerdi, H ; Tavakoli, R ; Yadav, P ; Prochowicz, D ; Saliba, M ; Tavakoli, M. M ; Sharif University of Technology
    American Chemical Society  2019
    Abstract
    PbS quantum dots (QDs) have been extensively studied for photovoltaic applications, thanks to their facile and low-cost fabrication processing and interesting physical properties such as size dependent and tunable band gap. However, the performance of PbS QD-based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report a low-power oxygen plasma treatment as a rapid and... 

    A Dopant-free hole transporting layer for efficient and stable planar perovskite solar cells

    , Article Physica Status Solidi - Rapid Research Letters ; Volume 14, Issue 7 , 2020 Tavakoli, M. M ; Si, H ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    Herein, a new dopant-free organic material, PV2000, as a stable hole transporting layer (HTL) for the fabrication of stable and efficient perovskite solar cells (PSCs) is introduced. For this purpose, planar PSCs using a triple-A cation perovskite composition are fabricated and the commonly used 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) HTL is replaced by dopant-free PV2000 polymer. The characterization results disclose that the PV2000 has a great thermal stability, good hole mobility, and suitable band alignment that matches well with the valence band of triple-A cation perovskite. After proper optimization of PV2000 film thickness, a planar PSC... 

    All-Vacuum-processing for fabrication of efficient, large-scale, and flexible inverted perovskite solar cells

    , Article Physica Status Solidi - Rapid Research Letters ; 2020 Tavakoli, M. M ; Tavakoli, R ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    Vacuum deposition of transporting layers, especially the hole-transporting layer (HTL), is still a big challenge for the fabrication of large-area perovskite solar cells (PSCs). In this work, efficient and large-area PSCs are fabricated by thermal evaporation of all the layers. Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) is used as the HTL, and a compact layer of PTAA with low thickness (2–10 nm) is successfully deposited using thermal evaporation. The optical and ultraviolet photoelectron spectroscopy (UPS) measurements prove that the evaporated PTAA has a great match with the single A-cation methylammonium triiodide perovskite film in terms of quenching effect and band... 

    Comparison between different DPC methods applied to DFIG wind turbines

    , Article International Journal of Renewable Energy Research ; Volume 3, Issue 2 , 2013 , Pages 446-452 ; 13090127 (ISSN) Tavakoli, S. M ; Pourmina, M. A ; Zolghadri, M. R ; Sharif University of Technology
    2013
    Abstract
    In this paper the direct power control methods of doubly fed induction generator in wind turbine applications are studied. In the methods under study, the proper voltage space vector of the rotor side converter is selected using a switching table which is derived from flux position and the difference between the measured and reference stator active and reactive powers. Various simulations are performed in Matlab/Simulink software on a DFIG system in order to investigate the dynamic performance and robustness of the proposed control methods against machine internal parameters variations  

    A hybrid pole climbing and manipulating robot with minimum DOFs for construction and service applications

    , Article Industrial Robot ; Volume 32, Issue 2 , 2005 , Pages 171-178 ; 0143991X (ISSN) Tavakoli, M ; Zakerzadeh, M. R ; Vossoughi, G. R ; Bagheri, S ; Sharif University of Technology
    2005
    Abstract
    Purpose - Aims to describe design, prototyping and characteristics of a pole climbing/manipulating robot with ability of passing bends and branches of the pole. Design/methodology/approach - Introducing a hybrid (parallel/serial) four degree of freedom (DOF) mechanism as the main part of the robot and also introduces a unique gripper design for pole climbing robots. Findings - Finds that a robot, with the ability of climbing and manipulating on poles with bends and branches, needs at least 4 DOFs. Also an electrical cylinder is a good option for climbing robots and has some advantages over pneumatic or hydraulic cylinders. Research limitations/implications - The robot is semi-industrial... 

    Efficient and less-toxic indium-doped mapbi3 perovskite solar cells prepared by metal alloying technique

    , Article Solar RRL ; Volume 6, Issue 9 , 2022 ; 2367198X (ISSN) Tavakoli, M. M ; Fazel, Z ; Tavakoli, R ; Akin, S ; Satapathi, S ; Prochowicz, D ; Yadav, P ; Sharif University of Technology
    John Wiley and Sons Inc  2022
    Abstract
    Perovskite materials with ABX3 structure (A: organic, B: metal, and X: halides) have attracted tremendous attention due to their outstanding optoelectronic properties. Herein, a novel approach is developed using chemical vapor deposition (CVD), i.e., metal alloying of halide-perovskite domain via ion-transfer (MAHDI) for the growth of high-quality perovskite films, grown directly from a metal precursor. This technique easily enables us to replace the toxic Pb metal (B site) with other metals using alloying approach. Using the proposed approach, we fabricated stable and efficient Pb–In perovskite solar cells (PSCs) with a maximum power conversion efficiency (PCE) of 21.2%, which is more... 

    On the glass-forming ability of (Zr0.5Cu0.5)100−xAlx ternary alloys: A molecular dynamics study

    , Article Materials Today Communications ; Volume 31 , 2022 ; 23524928 (ISSN) Abbasi, M. H ; Shabestari, S. G ; Tavakoli, R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    In this research, the atomic scale local structures in (Zr0.5Cu0.5)100−xAlx (x = 0,2,4,6,8,10,12) bulk metallic glass was studied using molecular dynamics simulation method. The pair distribution function, Voronoi analysis and mean squared displacement (MSD) were adopted for investigation of the local structures. It was found that Cu- and Al-centered full icosahedra possess the most frequency accompanied by the most changes during the glass transition process in the supercooled liquid region temperature. Moreover, it was observed that the Al-centered full icosahedra (Al-FI) and Cu-centered full icosahedra (Cu-FI) clusters with 2.5% and 1.9% increase (relative to total atoms), respectively,... 

    Radiation Effects on Geodesics in de Sitter Space: A Classical Approach

    , Article International Journal of Theoretical Physics ; Volume 51, Issue 6 , 2012 , Pages 1938-1945 ; 00207748 (ISSN) Fathi, M ; Tanhayi Ahari, M ; Tanhayi, M. R ; Tavakoli, F ; Sharif University of Technology
    2012
    Abstract
    In this work we first obtain a trajectory of a freely falling charged particle in de Sitter space and then in the classical approach, the effect of electromagnetic self-force on particle's trajectory has been considered. Finally, some limits for the problem have been presented  

    Interface engineering of perovskite solar cell using a reduced-graphene scaffold

    , Article Journal of Physical Chemistry C ; Volume 120, Issue 35 , Volume 120, Issue 35 , 2016 , Pages 19531-19536 ; 19327447 (ISSN) Tavakoli, M. M ; Tavakoli, R ; Hasanzadeh, S ; Mirfasih, M. H ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    Interface engineering of solar cell device is a prominent strategy to improve the device performance. Herein, we synthesize reduced-graphene scaffold (rGS) by using a new and simple chemical approach. In this regard, we synthesize a hollow structure of graphene and then fabricate a three-dimensional scaffold of graphene with a superior surface area using electrophoretic process. We employ this scaffold as an interface layer between the electron transfer and absorber layers in perovskite solar cell. The characterization tests and photovoltaic results show that rGS improves the carrier transportation, yielding a 27% improvement in device performance as compared to conventional device. Finally,... 

    Design, modeling and kinematics analysis of a novel serial/parallel pole climbing and manipulating robot

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 2 , 2004 , Pages 399-408 ; 0791841731 (ISBN); 9780791841730 (ISBN) Vossoughi, G. R ; Bagheri, S ; Tavakoli, M ; Zakerzadeh, M. R ; Hosseinzadeh, M ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Abstract
    This paper introduces a multi-task 4 DOF pole climbing/ manipulating robotic mechanism. A hybrid serial/parallel mechanism, providing 2 translations and 2 rotations, have been designed as the main part of the mechanism. This robotic mechanism can travel along tubular structures with bends, branches and step changes in cross section. It is also able to perform manipulation, repair and maintenance tasks after reaching the target point on the structure. After introducing the mechanism, a kinematics model and the forward and inverse kinematics as well as the workspace analysis of the mechanism are presented  

    The effect of fuel cell operational conditions on the water content distribution in the polymer electrolyte membrane

    , Article Renewable Energy ; Volume 36, Issue 12 , December , 2011 , Pages 3319-3331 ; 09601481 (ISSN) Tavakoli, B ; Roshandel, R ; Sharif University of Technology
    2011
    Abstract
    Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two-dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro-osmotic drag and convection. The effect of current density variation distribution on the water content (λ) in membrane/electrode assembly (MEA) was determined. In this work the membrane heat conductivity is considered as a... 

    The discrete time-cost-quality trade-off problem using a novel hybrid genetic algorithm

    , Article Applied Mathematical Sciences ; Volume 4, Issue 41-44 , 2010 , Pages 2081-2094 ; 1312885X (ISSN) Shahsavari Pour, N ; Modarres, M ; Aryanejad, M. B ; Tavakoli Moghadam, R ; Sharif University of Technology
    2010
    Abstract
    Time, cost and quality are among the major objectives of any project. In recent years, the demands of project stakeholders regarding reductions in the total cost and time of a project along with achieving the desirable quality of the project have risen significantly. This leads researchers to developing models that incorporate the quality factor to previously existing time-cost trade-off models. This study presents a model for the discrete time-cost-quality trade-off problem. In this model there are a number of execution modes to select for each activity, and the best execution mode (t, c, q) of the activities should be determined to optimize total cost and time objectives, subjected to... 

    Surface modification of a hole transporting layer for an efficient perovskite solar cell with an enhanced fill factor and stability

    , Article Molecular Systems Design and Engineering ; Volume 3, Issue 5 , 2018 , Pages 717-722 ; 20589689 (ISSN) Tavakoli, M. M ; Tavakoli, R ; Prochowicz, D ; Yadav, P ; Saliba, M ; Sharif University of Technology
    2018
    Abstract
    The improvement of the quality of the hole transporting layer (HTL) plays a key role in the fabrication of highly efficient and stable perovskite solar cells (PSCs). Here, we used rubrene as a surface treatment agent on top of a spiro HTL. We found that rubrene can cover the pinholes of the spiro layer and provide an excellent contact layer for planar PSCs. Based on this modification, mobile gold ions from the metal electrode are prevented from diffusing through the HTL hindering the degradation of PSCs. The optimized device shows a maximum power conversion efficiency (PCE) of 19.87% and a 79% fill factor (FF), which are higher than the 17.98% PCE and 72% FF of the reference device. In... 

    Study of the dependence of the specific output power of a copper chloride laser on the radial temperature profile of a gas plasma

    , Article Quantum Electronics ; Volume 37, Issue 4 , 2007 , Pages 325-330 ; 10637818 (ISSN) Sadighi Bonabi, R ; Soltanmoradi, F ; Mohammadpour, R ; Tavakoli, M ; Zand, M ; Sharif University of Technology
    2007
    Abstract
    The design of a copper chloride laser is described, and the laser is optimised by studying the dependence of its output power on the buffer gas type. The voltage and current of the laser discharge at the optimum buffer gas pressure are measured. The influence of the diaphragm diameter on the specific output power is studied after optimisation of switch parameters. When an diaphragm producing the optimal temperature gradient in the laser gas-discharge tube, the record specific output power of 123 W L-1 is obtained without any admixtures. ©2007 Kvantovaya Elektronika and Turpion Ltd  

    CuCl-Ne laser construction and its optimization on the specific output power

    , Article Lasers and Applications, Warsaw, 28 August 2005 through 2 September 2005 ; Volume 5958 , 2005 , Pages 1-7 ; 0277786X (ISSN) Sadighi Bonabi, R ; Mohammadpour, R ; Tavakoli, M ; Soltanmoradi, F ; Zand, M ; Sharif University of Technology
    2005
    Abstract
    In this work, after construction of a copper chloride laser, the effect of using different buffer gases on the output power has been examined. The voltage, current, laser pulses and the far field pattern of laser intensity were measured at the optimum buffer gas pressure. At these favorable conditions, the effect of using diaphragms in different diameters on the specific output power has been studied. By finding the desirable diaphragm size which creates the best temperature gradient in the laser tube the specific output record power of 123 (Watt/Lit) was obtained