Sharif Digital Repository

Interfacial engineering between the perovskite and hole transport layers has emerged as an effective way to improve perovskite solar cell (PSC) performance. A variety of organic halide salts are developed to passivate the traps and enhance the charge carrier transport. Here, the use of guanidinium iodide (GuaI) for interfacial modification of mixed-cation (Cs)x(FA)1−xPbI3 perovskite films, which results in the formation of a low-dimensional δ-FAPbI3-like phase on the 3D perovskite surface, is reported. The presence of this thin layer facilitates charge transfer at interfaces and reduces charge carrier recombination pathways as evidenced by enhanced carrier lifetimes and favorable interfacial... 

Titanium dioxide (TiO2) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C60 derivative (C60-BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO2 ETL with C60-BCT@Au NPs... 

The quality of perovskite films plays a crucial role in improving the optoelectronic properties and performance of perovskite solar cells (PSCs). Herein, high-quality CsxFA1−xPbI3 perovskite films with different compositions (x = 0, 5, 10, and 15) are achieved by controlling the amount of cesium chloride (CsCl) in the respective FAPbI3 precursor solution. The effects of CsCl addition on the morphological and optoelectronic properties of the resulting perovskite films and on the performance of the corresponding devices are systematically studied. Introduction of CsCl into FAPbI3 shows a great potential to stabilize the α-FAPbI3 perovskite phase by forming CsxFA1−xPbI3 films with improved... 

Interface engineering has emerged as a great strategy for fabrication of high efficiency and stable perovskite solar cells (PSCs). Here, we deposit a thin layer of ZnS as a buffer layer at the interface of the perovskite absorber and electron transporting layer (ETL) using the atomic layer deposition (ALD) process. The impact of the ZnS layer on the photovoltaic characteristics of PSCs was investigated by comparison of two mesoscopic configurations, in which the ZnS layer is grown on compact TiO2 and on mesoporous TiO2 surfaces. Our results revealed that the addition of an ultrathin ZnS layer between the perovskite and ETL drastically improves the charge extraction properties and reduces... 

Fullerene derivatives with a strong electron-accepting ability play a crucial role in enhancing both the performance and stability of perovskite solar cells (PSCs). However, most of the used fullerene molecules are based on [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which limits the device performance due to difficulties in preparing high-quality and uniform thin films. Herein, solution-processable azahomofullerene (AHF) derivatives (abbreviated as AHF-1 and AHF-2) are reported as novel and effective electron-transport layers (ETLs) in p-i-n planar PSCs. Compared to the control PCBM ETL-based PSCs, the devices based on AHFs exhibit higher photovoltaic performances, which is... 

Perovskite solar cells (PSCs) have experienced outstanding advances in power conversion efficiencies (PCEs) by employing new electron transport layers (ETLs), interface engineering, optimizing perovskite morphology, and improving charge collection efficiency. In this work, we study the role of a new ultrathin interface layer of titanium nitride (TiN) conformally deposited on a mesoporous TiO2 (mp-TiO2) scaffold using the atomic layer deposition method. Our characterization results revealed that the presence of TiN at the ETL/perovskite interface improves the charge collection as well as reduces the interface recombination. We find that the morphology (grain size) and optical properties of... 

This paper aims to revisit the effect of sloshing on the flutter characteristics of a partially liquid-filled cylinder. A computational fluid-structure interaction model within the framework of the finite element method is developed to capture fluid-structure interactions arising from the sloshing of the internal fluid and the flexibility of its containing structure exposed to an external supersonic airflow. The internal liquid sloshing is represented by a more sophisticated model, referred to as the liquid sloshing model, and the shell structure is modeled by Sanders' shell theory. The aerodynamic pressure loading is approximated by the first-order piston theory. The initial geometric... 

Capture of discrete nature of nanomaterials is central to predict their behavior in high precision. To this end, various augmented continuum theories have been presented. However, their accuracy is strongly dependent on the recognition of accurate values of associated characteristic length scale parameter, and many ambiguities and uncertainties still remain about them. As main purpose of this study, the accurate values of elasticity tensor elements in the framework of first strain gradient theory are calculated for graphene with trigonal crystal system. A promising way to achieve them could be through molecular mechanics model. So that, the energy, including strain and kinetic energy, based... 

Co/SBA-15 nanoparticle catalysts (CoNP) were prepared using a commonly adapted synthetic route and then utilised for esterification and amidation reactions using aromatic and linear chain compounds for the production of long chain esters and amides. The study shows that the use of CoNP catalysts favours the use of aromatic reactants with electron donating substituents specifically in the para position. For the amidation reaction, good to excellent yields were obtained demonstrating tolerance towards differently substituted aromatic compounds. Overall, the synthesized catalysts proved to be efficient and highly versatile, and recyclable under the investigated conditions  

This paper presents a numerical scheme for stability analysis of the aeroelastic systems in the Laplace domain. The proposed technique, which is called the PP method, is proposed for when the aerodynamic model is represented in the Laplace domain and includes complicated transcendental expressions in terms of the Laplace variable. This method utilizes a matrix iterative procedure to find the eigenvalues of the system and generalizes the other methods such as the P and PK methods for prediction of the flutter conditions. The major advantage of this technique over the other approximate methods is true prediction of subcritical damping and frequency values of the aeroelastic modes. To examine... 

In this paper a lower bounding method for the flowshop sequence dependentgroups scheduling problems by minimization of makespan criterion (Fm|fmls, Sijkprmu|Cmax) is proposed. Theperformance of the proposed lower bound (LB) is compared with the availablelower bounding methods in literature. In order to do this, the performance ofthe proposed LB and the one available in literature are compared with theavailable upper bound in literature based on solving the available testproblems. The results show that the proposed LB has a superior performancecompared to the available ones in literature. The average percentage error ofthe proposed LB for the test problems is 1.1% and 1.4% for three and six... 

Physics-informed neural networks (PINNs) have received significant attention as a unified framework for forward, inverse, and surrogate modeling of problems governed by partial differential equations (PDEs). Training PINNs for forward problems, however, pose significant challenges, mainly because of the complex non-convex and multi-objective loss function. In this work, we present a PINN approach to solving the equations of coupled flow and deformation in porous media for both single-phase and multiphase flow. To this end, we construct the solution space using multi-layer neural networks. Due to the dynamics of the problem, we find that incorporating multiple differential relations into the... 

In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. The effects of intermittent irrigation, type of agglomeration, feed formulation in terms of acid, enriched salt solution, initial number of microorganism, and their interactions on the bioleaching of low-grade zinc sulfide ores (containing 5.78% zinc) on growth and biooxidation efficiency of the bacteria have been evaluated. Bioleaching capacities of the isolate were optimized by the utilization the Taguchi method (e-qualitic-4) for design of experiments. As a result,... 

Security techniques have been designed to obtain certain objectives. One of the most important objectives all security mechanisms try to achieve is the availability, which insures that network services are available to various entities in the network when required. But there has not been any certain parameter to measure this objective in network. In this paper we consider availability as a security parameter in ad-hoc networks. However this parameter can be used in other networks as well. We also present the connectivity coefficient of nodes in a network which shows how important is a node in a network and how much damage is caused if a certain node is compromised  

Performance of routing is severely degraded when misbehaving nodes drop packets instead of properly forwarding them. In this paper, we propose a Game-Theoretic Adaptive Multipath Routing (GTAMR) protocol to detect and punish selfish or malicious nodes which try to drop information packets in routing phase and defend against collaborative attacks in which nodes try to disrupt communication or save their power. Our proposed algorithm outranks previous schemes because it is resilient against attacks in which more than one node coordinate their misbehavior and can be used in networks which wireless nodes use directional antennas. We then propose a game theoretic strategy, ERTFT, for nodes to... 

Deep eutectic solvents (DESs), surmised as "the organic reaction medium of the century", have reverberated a new symphony throughout the present green millennium. A brief historical account of the DES systems and their physicochemical properties as task-specific and designer solvents for cross-coupling reactions are appraised including the hole theory that explains the underlying mechanistic pathway for this emerging neoteric medium. The insights into cross-coupling reactions and their applications are included, highlighting the significant achievements pertaining to the dual role of DESs as a solvent and catalyst. In addition, popular "name-reactions"for the carbon-carbon and... 

Let n be a positive integer and let Sn be the set of all nonnegative integers less than n which are relatively prime to n. In this paper, we discuss structural properties of circulant graphs generated by the Sn′s and their complements. In particular, we characterize when these graphs are well-covered, Cohen–Macaulay, Buchsbaum or Gorenstein. © 2020, Springer Science+Business Media, LLC, part of Springer Nature  

The effect of wall cooling in tray-type solid-state fermenters was investigated by cultivation of Aspergillus niger ATCC 10 864 on wheat bran. Temperature, moisture, pH and glucoamylase activity in the bed were monitored. Application of the heat exchanger plate reduced the overall water loss but increased the heterogeneity of moisture distribution in the bed. Moisture content increased markedly close to the heat transfer plate while the upper regions of the bed dried out. The thermal conductivity of the bed was measured to be 0.19 Wm-1 K-1. At these conditions and depending on the air flow rate, 58-82% of the metabolic heat was removed via conduction towards the plate. A mathematical model... 

Let n be a positive integer and let Sn be the set of all nonnegative integers less than n which are relatively prime to n. In this paper, we discuss structural properties of circulant graphs generated by the Sn’s and their complements. In particular, we characterize when these graphs are well-covered, Cohen–Macaulay, Buchsbaum or Gorenstein. © 2020, Springer Science+Business Media, LLC, part of Springer Nature