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    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
    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... 

    Modeling of shot-peening effects on the surface properties of a (Tib + Tic)/Ti-6Al-4V composite employing artificial neural networks

    , Article Materiali in Tehnologije ; Volume 50, Issue 6 , 2016 , Pages 851-860 ; 15802949 (ISSN) Maleki, E ; Zabihollah, A ; Sharif University of Technology
    Institute of Metals Technology 
    Abstract
    Titanium matrix composites (TMCs) have wide application prospects in the field of aerospace, automobile and other industries because of their good properties, such as high specific strength, good ductility, and excellent fatigue properties. However, in order to improve their fatigue strength and life, crack initiation and growth at the surface layers must be suppressed using surface treatments. Shot peening (SP) is an effective surface mechanical treatment method widely used in industry which can improve the mechanical properties of a surface. However, artificial neural networks (ANNs) have been used as an efficient approach to predict and optimize the science and engineering problems. In... 

    Optimization of shot peening effective parameters on surface hardness improvement

    , Article Metals and Materials International ; June , 2020 Maleki, E ; Unal, O ; Sharif University of Technology
    Korean Institute of Metals and Materials  2020
    Abstract
    Abstract: Shot peening is well-known process for mechanical properties integrity in metallic materials. In present study influences of different shot peening treatments on the surface hardness of different carbon steels were investigated experimentally and then alternative approach by using artificial neural network is presented for hardness prediction of the shot peened surface. After modeling a comprehensive parametric investigations and sensitivity analysis were applied according to the influence of the related effective parameters on surface hardness improvements. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials  

    Scattering of a Gaussian beam by a spherical dielectric object using the vectorial Gaussian beam tracing method

    , Article ICCEA 2004 - 2004 3rd International Conference on Computational Electromagnetics and its Applications, Beijing, 1 November 2004 through 4 November 2004 ; 2004 , Pages 72-75 ; 0780385624 (ISBN); 9780780385627 (ISBN) Shishegar, A. A ; Sharif University of Technology
    2004
    Abstract
    Scattering of a Gaussian beam by a spherical dielectric object is studied using the vectorial Gaussian beam tracing method. Expansion to a few Gaussian beams with the smaller waists has been used to extend the method to a more generalized one. This method can be applied to a large variety of different shape objects and incident beam profiles. Numerical results of this computationally fast method show a good agreement with the results represented in the literature. © 2004 IEEE  

    Co surface modification by bias sputtering in Cu/Co(Vb)/NiO/ Si(100) magnetic multilayer structures

    , Article Physica Status Solidi C: Conferences ; Volume 1, Issue 7 , 2004 , Pages 1744-1747 ; 16101634 (ISSN) Moshfegh, A. Z ; Sangpour, P ; Sharif University of Technology
    2004
    Abstract
    To investigate the Ta/Co/Cu/Co/NiO/Si(100) spin valve structure, fabrication and characterization of the Cu/Co/NiO/Si(100) system was studied for further understanding the structure. The system was grown by employing combinative DC sputtering-evaporation technique. Nickel oxide with a thickness of about 30 nm was deposited on Si(100) substrate using thermal evaporation technique.The cobalt film, then, with a thickness of about 3 nm was grown by DC sputtering under various applied negative bias voltages ranging from 0 to - 80 V. The optimum bias voltage (Vb = -60 V) for the growth of Co layer was determined by atomic force microscopy (AFM), four-point probe sheet measurement (Rs) and scanning... 

    Study on Effects of Short Wood Fibers on Physical and Mechanical Properties of Biodegradable Composite Based on Thermoplastic Starch

    , M.Sc. Thesis Sharif University of Technology Pesaran Haji Abbas, Ehsan (Author) ; Bagheri, Reza (Supervisor) ; Sayyed Reihani, Morteza (Supervisor)
    Abstract
    Due to the negative effects of conventional plastics on the enviroment, especially in the packaging sector, extensive efforts have been put to replace these polymers with biodegradable polymers. Starch is one of the biodegradable polymers which has attracted a lot of attentions because of low cost and good processability. Native starch has the form of granule and can be processed to a continuous phase after gelatinization in the presence of a plasticizer. The resulting material is a biodegradable plastic-like material called thermoplastic starch (TPS) which is processed using conventional technologies, but suffers from low mechanical properties and high hydrophilicity. Addition of natural... 

    “ Nano Oxide Layer Forming on the Surface of Porous Nitinol Shape Memory Alloy for Improving Surface Properties “

    , M.Sc. Thesis Sharif University of Technology Fattahzadeh, Mehrdad (Author) ; Sadrnejhad, Khatiboleslam (Supervisor)
    Abstract
    In this project ,it has been done different surface treatment on 6 samples of nitinol with 40 % prosity,three of them are anodized by H2SO4 ,Hf, Acetic acid, one of them is treated with plasma spray with TIO2 powder, one of them is putted in the furnace at 700 degrees for an hour, and the last one is bare ; Moreover, these treated samples are putted in Simulated body fluid for 16 days . After this period of time, we analyzed the results. Then the cell adhesion amount of osteo blast cells (MG 63) is measured to these samples by immersing them for 3 days in these cells.The results are investigated by SEM ,XRD(X pertpro produced by Panalitical), XRF(530-XRF-01), AAS( AA240), Roughness measuring... 

    An easy method to modify PEDOT:PSS/perovskite interfaces for solar cells with efficiency exceeding 15%

    , Article RSC Advances ; Volume 6, Issue 70 , 2016 , Pages 65594-65599 ; 20462069 (ISSN) Shahbazi, S ; Tajabadi, F ; Shiu, H. S ; Sedighi, R ; Jokar, E ; Gholipour, S ; Taghavinia, N ; Afshar, S ; Diau, E. W. G ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Abstract
    Herein, we show that surface treatment of PEDOT:PSS films using propionic acid (PA) results in better device performance for the resulting CH3NH3PbI3 perovskite solar cells (PCE > 15%). N2 blow spreading of PA appears critical in enhanced performance. This weak acid treatment leads to no worse roughness, while providing larger perovskite grains  

    Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment

    , Article Polymers and Polymer Composites ; Volume 14, Issue 6 , 2006 , Pages 585-589 ; 09673911 (ISSN) Nematollahzadeh, A ; Mousavi, S. A. S ; Tilaki, R. M ; Frounchi, M ; Sharif University of Technology
    Rapra Technology Ltd  2006
    Abstract
    The impact strength of poly(methyl methacrylate)/caibon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mj per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest... 

    Developing an Analytical Model for Predicting the Residual Stresses Induced by Shot Peening with Considering the Effect of Initial Surface Treatment

    , Ph.D. Dissertation Sharif University of Technology Sherafatnia, Khalil (Author) ; Farrahi, Gholam Hossein (Supervisor) ; Mahmoudi, Amir Hossein (Co-Supervisor)
    Abstract
    Shot peening is a cold-working process commonly used in industry to improve the fatigue performance, stress corrosion resistance and surface nano-crystallization of metallic parts. This process extends fatigue life via two mechanisms: Preventing the crack growth due to compressive residual stresses and, preventing the crack initiation because of increased material hardness. These mechanisms are the results of the bombardment of the component's surface with small spherical particles. In this research, an analytical model is developed for estimating the residual stress distribution induced by shot peening process. The modifications of the developed analytical model are related to... 

    Communication - Co-electrodeposition of Ni/SiO2(CH2)3SH composite: Modified Guglielmi’s model and mechanism of nucleation

    , Article Journal of the Electrochemical Society ; Volume 164, Issue 13 , 2017 , Pages E472-E474 ; 00134651 (ISSN) Fazlolahzadeh, O ; Rouhollahi, A ; Dolati, A ; Ghahramanifard, F ; Sharif University of Technology
    Electrochemical Society Inc  2017
    Abstract
    This work studies the influence of surface modification of silica nanoparticles by mercaptopropyl trimethoxysilane on silica weight percent in Ni coating during electrodeposition. Results showed SiO2(CH2)3SH particles were embedded in the Ni coating up to 11%. Also, modified Guglielmi’s model and mechanicsm of nucleation of Ni-SiO2(CH2)3SH composite were studied. © 2017 The Electrochemical Society. All rights reserved  

    Adhesion modification of polyethylenes for metallization using radiation-induced grafting of vinyl monomers

    , Article Surface and Coatings Technology ; Volume 201, Issue 16-17 , 2007 , Pages 7519-7529 ; 02578972 (ISSN) Shojaei, A ; Fathi, R ; Sheikh, N ; Sharif University of Technology
    2007
    Abstract
    The present paper demonstrates the performance of the radiation grafting technique as a chemically based surface pretreatment method to adhesion modification of polyethylene surfaces toward the metallic layer. Gamma irradiation over a dose range of 4-10 kGy is used for grafting of vinyl monomers including acrylamide (AAm) and 1-vinyl-2-pyrrolidone (NVP) onto the surface of three different polyethylenes including low density polyethylene (LDPE) and two kinds of high density polyethylenes, namely HDPE-1 and HDPE-2. The grafting yield is evaluated based on the weight increase of the samples. It is found that the grafting yield is dominated by the crystallinity of the polyethylene, so that lower... 

    Decolorization of denim fabrics with cold plasmas in the presence of magnetic fields

    , Article Plasma Processes and Polymers ; Volume 3, Issue 3 , 2006 , Pages 316-321 ; 16128850 (ISSN) Ghoranneviss, M ; Moazzenchi, B ; Shahidi, S ; Anvari, A ; Rashidi, A ; Sharif University of Technology
    2006
    Abstract
    Denim jeans have consistently been fashionable around the world. This fabric inspired strong opinions from historians, teenagers, and movie stars, and has acquired different styles throughout the years. Most jeans today are stonewashed; this technique first become popular in 1970. Now, in addition to pumice stones, enzymes are used on the cotton fabrics to create the stonewashed look. Nowadays, plasma treatment is a cost-effective and environment-friendly process which is able to modify the properties of the fabric surface in order to achieve this effect. Plasma surface treatment changes the properties of the fabric up to a limited depth (several molecular layers), leaving the bulk... 

    Surface modification of exchange-coupled Co/NiO x magnetic bilayer by bias sputtering

    , Article Applied Surface Science ; Volume 252, Issue 2 , 2005 , Pages 466-473 ; 01694332 (ISSN) Sangpour, P ; Akhavan, O ; Moshfegh, A. Z ; Jafari, G. R ; Kavei, G ; Sharif University of Technology
    Elsevier  2005
    Abstract
    We have investigated the effect of bias voltage on sheet resistance, surface roughness and surface coverage of Co/NiO x magnetic bilayer. In addition, interface topography and corrosion resistance of the Ta/Co/Cu/Co/NiO x /Si(1 0 0) system have been studied for Co layers deposited at an optimum bias voltage. Atomic force microscopy (AFM) and four point probe sheet resistance (Rs) measurement have been used to determine surface and electrical properties of the sputtered Co layer at different bias voltages ranging from 0 to -80 V. The Co/NiO x bilayer exhibits a minimum surface roughness and low sheet resistance value with a maximum surface coverage at Vb=-60 V resulted in a slight increase of... 

    Chromium carbonitride coating produced on DIN 1.2210 steel by thermo-reactive deposition technique: Thermodynamics, kinetics and modeling

    , Article Surface and Coatings Technology ; Volume 225 , 2013 , Pages 1-10 ; 02578972 (ISSN) Khalaj, G ; Nazari, A ; Khoie, S. M. M ; Khalaj, M. J ; Pouraliakbar, H ; Sharif University of Technology
    2013
    Abstract
    A duplex surface treatment on DIN 1.2210 steel has been developed involving nitriding and followed by chromium thermo-reactive deposition (TRD) techniques. The TRD process was performed in molten salt bath at 550, 625 and 700°C for 1-14h. The process formed a thickness up to 9.5μm of chromium carbonitride coatings on a hardened diffusion zone. Characterization of the coatings by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) indicates that the compact and dense coatings mainly consist of Cr(C,N) and Cr2(C,N) phase. All the growth processes of the chromium carbonitride obtained by TRD technique followed a parabolic kinetics. Activation energy (Q) for the... 

    Characterisation of Ni-Ti intermetallic coatings formed on Cp titanium by diffusion treatment

    , Article International Journal of Surface Science and Engineering ; Volume 9, Issue 1 , 2015 , Pages 43-54 ; 1749785X (ISSN) Khosravi, G ; Sohi, M. H ; Ghasemi, H. M ; Vafadar, A. Kh ; Sharif University of Technology
    Inderscience Enterprises Ltd  2015
    Abstract
    In order to produce a thick near equi-atomic NiTi intermetallic layer on the surface of titanium plate, layers of nickel with thicknesses of 30 μm and 60 μm were electroplated on commercial pure (Cp) titanium and subsequently were heat treated at 850°C and 900°C. The effects of heat treating temperature and the thickness of electroplated nickel on the evolution of the microstructure and mechanical properties were studied. The results confirm the formation of various intermetallic layers in the coatings that substantially affect their hardness. The optimum condition for the formation of a thick NiTi intermetallic layer on the outer surface of the titanium was diffusion treatment of the sample... 

    Improved adhesion of NiTi wire to silicone matrix for smart composite medical applications

    , Article Materials and Design ; Volume 30, Issue 9 , 2009 , Pages 3667-3672 ; 02641275 (ISSN) Sadrnezhaad, Kh ; Hassanzadeh Nemati, N ; Bagheri, R ; Sharif University of Technology
    2009
    Abstract
    Recent uses of intelligent composites in biomedical appliances aggrandize the necessity of bonding-strength improvement in NiTi/silicone matrix interface. SEM micrographs and pull-out tests are employed to determine the strength of the NiTi/silicone bonds in a flexible composite piece. Greater adhesion strengths are obtained due to the presence of thin oxide layer, surface roughness and frictional forces between the embedded-wires and the contacting phase. Effect of curing treatment on phase transformation temperatures of the wires is determined by electrical resistivity (ER) measurements. Results show that the curing treatment shifts the transition points of the wires towards higher... 

    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... 

    , M.Sc. Thesis Sharif University of Technology (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    In the preceding years, hydroxyapatite (HA)-based coatings and scaffolds have been known as the best biomaterials for dental and orthopedics applications. Biocompatible and bioactive hydroxyapatite-based Coatings on metallic implants is one of the best methods for reaching both suitable mechanical properties and appropriate bioactivity, leading to better osseointegration and osteoblast proliferation. The ultimate goal of this project is characterization as well as mechanical and electrochemical behavior investigation of Hydroxyapatite- Chitosan nanocomposite coating by electrophoretic deposition (EPD) method on Plasma Electrolyte Oxidation (PEO) treated titanium substrates and Magnesium (Mg)... 

    The effect of multiple surface treatments on biological properties of Ti-6Al-4V alloy

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 10 , 2014 , p. 4588-4593 Parsikia, F ; Amini, P ; Asgari, S ; Sharif University of Technology
    Abstract
    In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface...