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Characterization of interfaces: Lessons from the past for the future of perovskite solar cells

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Journal of Semiconductors 2022年第5期43卷 58-69页

作者： Wanlong Wang Dongyang Zhang Rong Liu Deepak Thrithamarassery Gangadharan Furui Tan Makhsud I.Saidaminov Key Laboratory of Photovoltaic Materials Henan UniversityKaifeng 475004China department of Chemistry Department of Electrical&Computer Engineeringand Centre for Advanced Materials and Related Technologies(CAMTEC)University of VictoriaVictoriaBritish Columbia V8P 5C2Canada

A photovoltaic technology historically goes through two major steps to evolve into a mature technology. The first step involves advances in materials and is usually accompanied by the rapid improvement of power conversion efficiency. The second step focuses on interfaces and is usually accompanied by significant stability improvement. As an emerging generation of photovoltaic technology, perovskite solar cells are transitioning to the second step of their development when a significant focus shifts toward interface studies and engineering. While various interface engineering strategies have been developed, interfacial characterization is crucial to show the effectiveness of interfacial modification. Here, we review the characterization techniques that have been utilized in studying interface properties in perovskite solar cells. We first summarize the main roles of interfaces in perovskite solar cells, and then we discuss some typical characterization methodologies for morphological, optical,and electrical studies of interfaces. Successful experiences and existing problems are analyzed when discussing some commonly used methods. We then analyze the challenges and provide an outlook for further development of interfacial characterizations. This review aims to evoke strengthened research devotion on novel and persuasive interfacial engineering.

关键词： interface perovskite solar cells characterization methods

Fabrication and testing of polymer-based capacitive micromachined ultrasound transducers for medical imaging

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Microsystems & Nanoengineering 2018年第1期4卷 178-189页

作者： Carlos D.Gerardo Edmond Cretu Robert Rohling department of electrical and computer engineering University of British Columbia2332 Main MallVancouverBCCanada department of Mechanical engineering University of British Columbia6250 Applied Science LnVancouverBCCanada

The ultrasonic transducer industry is dominated by piezoelectric materials.As an emerging alternative,capacitive micromachined ultrasound transducers(CMUTs)offer wider bandwidth,better integration with electronics,and ease of fabricating large arrays.CMUTs have a sealed cavity between a fixed electrode and a suspended metalized membrane.Manufacturing cost and sensitivity are limiting factors in current CMUTs that depend on the fabrication equipment and,especially,on the materials used.For widespread use of CMUTs,a much lower fabrication cost that uses inexpensive materials,which maintain or improve upon existing sensitivity,is needed.Herein,a new fabrication process is described for polymer-based CMUTs(polyCMUTs)using the photopolymer SU-8 and Omnicoat.The first ultrasound B-mode image of a wire phantom created with a 64-element linear array using synthetic aperture beamforming techniques is presented.A 12 VAC signal superimposed on a 10 VDC signal was used on the transmission side,and only a bias-tee,with no amplifiers,was used on the receiving side.The low operational voltage and high sensitivity of this device can be partially attributed to a pre-biasing condition on the membrane.By using a novel sacrificial layer combined with a top electrode embedded inside the membrane,we demonstrated that SU-8 can be used to manufacture CMUTs inexpensively.Moreover,the fabrication used relatively simple equipment,and the number of fabrication steps was reduced compared to traditional CMUT fabrication.This new fabrication process has the potential to increase the use of CMUTs in the ultrasound market,including the market for wearable transducers.

关键词： polymer electrode testing

In Situ Iodide Passivation Toward Efficient CsPbI_(3) Perovskite Quantum Dot Solar Cells

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Nano-Micro Letters 2023年第10期15卷 28-39页

作者： Junwei Shi Ben Cohen‑Kleinstein Xuliang Zhang Chenyu Zhao Yong Zhang Xufeng Ling Junjun Guo Doo‑Hyun Ko Baomin Xu Jianyu Yuan Wanli Ma department of Materials Science and engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Institute of Functional Nano&Soft Materials(FUNSOM) Soochow University199 Ren‑Ai RoadSuzhou Industrial ParkSuzhou 215123People’s Republic of China department of electrical and computer engineering University of British Columbia2329 West MallVancouverBC V6T 1Z4Canada department of Chemistry Sungkyunkwan UniversitySuwon 16419Republic of Korea Jiangsu Key Laboratory of Advanced Negative Carbon Technologies Soochow University199 Ren‑Ai RoadSuzhou Industrial ParkSuzhou 215123People’s Republic of China Jiangsu Key Laboratory for Carbon‑Based Functional Materials&Devices Soochow University199 Ren‑Ai RoadSuzhou Industrial ParkSuzhou 215123People’s Republic of China

All-inorganic CsPbI_3 quantum dots(QDs) have demonstrated promising potential in photovoltaic(PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid(HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI_2 into highly coordinated [PbI_m]~(2-m), enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on ofurther understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.

关键词： CsPbI_(3)perovskite quantum dots In situ passivation Surface trap states Perovskite solar cell

A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO behaviors within GIS

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Frontiers in Energy 2014年第1期8卷 90-100页

作者： Mehrdad MAJIDI Hamid JAVADI Moein MANBACHI department of electrical & computer engineering Power & WaterUniversity of Technology Tehran Iran School of engineering Science Simon Fraser University 8888 University Drive Burnaby British Columbia Canada

One of the fundamental issues in gas insulated substations （GIS） which has destructive effects on GIS equipment is the very fast transient over-voltages （VFTOs）. This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemen- ted on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.

关键词： comsol multiphysics EMTP-RV ferrite ring,gas insulated substations （GIS） transient over-voltage,insulation coordination

Mutual Information and Energy Tradeoff in Correlated Wireless Sensor Networks

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Mutual Information and Energy Tradeoff in Correlated Wireles...

Stability Analysis and Performance Evaluation of Delayed Bilateral Telerobotic Systems over a Lossy Communication Channel

2008 IEEE International Conference on Communications(ICC 2008)

作者： Laxminarayana S Pillutla Vikram Krishnamurthy department of electrical and computer engineering the university of british columbia 2332 main mall VancouverBC V6T1Z4Canada

We consider comparison of Mutual Information （MI）-Energy tradeoff in correlated wireless sensor network （WSN） for cooperative multiple input and multiple output （MIMO） and non-cooperative （referred to as single input and single output （SISO）） transmission schemes.Our numerical results indicate that for short distances SISO schemes achieve better MI-Energy tradeoff than the cooperative MIMO schemes,while for long distances the cooperative MIMO schemes achieve better MI-Energy tradeoff.We next consider the issue of sensor placement in a correlated WSN.Specifically,we prove that the spacing between nodes to maximize MI is in general an increasing function of observation SNR.From this structural result,we conclude that at high SNR,the various stages of the WSN can be separated by relatively large distances than at low SNR.

关键词： Mutual information Wireless sensor networks MIMO Peer to peer computing Energy consumption Communications Society Batteries Encoding Energy efficiency Source coding

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Journal of Systems Science & Complexity 2021年第1期34卷 157-179页

作者： BAKHSHI Ali ALFI Alireza TALEBI Heidar Ali SOURATGAR Amir Aboulfazl YOUSEFI Mahdi Faculty of electrical and Robotic engineering Shahrood University of TechnologyShahrood 36199-95161Iran Power Plants Control Systems Technology Development Plan Department of monitoring and ControlNiroo Research InstituteTehran 14665-517Iran Real-Time and Robotics system Laboratory Faculty of Electrical EngineeringAmirkabir University of TechnologyHafez AvenueTehran 15914Iran electrical and computer engineering department The University of British Columbia2385East MallVan couverBC V6T 1Z4Canada

The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and time delay in the communication channel. Different control strategies have been reported to compensate the effects of time delay in the communication channel;however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous pulses.To improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the time delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.

关键词： Lossy channel passivity stability telerobotic transparency

A machine vision tool for facilitating the optimization of large-area perovskite photovoltaics

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npj Computational Materials 2021年第1期7卷 1764-1773页

作者： Nina Taherimakhsousi Mathilde Fievez Benjamin P.MacLeod Edward P.Booker Emmanuelle Fayard Muriel Matheron Matthieu Manceau Stéphane Cros Solenn Berson Curtis P.Berlinguette department of Chemistry The University of British Columbia2036 Main MallVancouverBC V6T 1Z1Canada Univ.Grenoble Alpes CEALITENCampus Ines73375 Le Bourget du LacFrance Stewart Blusson Quantum Matter Institute The University of British Columbia2355 East MallVancouverBC V6T 1Z4Canada School of electrical engineering and computer Science University of Ottawa800 King Edward AvenueOttawaON K1N 6N5USA department of Chemical&Biological engineering The University of British Columbia2360 East MallVancouverBC V6T 1Z3Canada Canadian Institute for Advanced Research(CIFAR) MaRS Innovation Centre661 University Avenue Suite 505M5G 1M1 TorontoONCanada

We report a fast,reliable and non-destructive method for quantifying the homogeneity of perovskite thin films over large areas using machine vision.We adapt existing machine vision algorithms to spatially quantify multiple perovskite film properties(substrate coverage,film thickness,defect density)with pixel resolution from pictures of 25 cm2 samples.Our machine vision tool—called PerovskiteVision—can be combined with an optical model to predict photovoltaic cell and module current density from the perovskite film thickness.We use the measured film properties and predicted device current density to identify a posteriori the process conditions that simultaneously maximize the device performance and the manufacturing throughput for large-area perovskite deposition using gas-knife assisted slot-die coating.PerovskiteVision thus facilitates the transfer of a new deposition process to large-scale photovoltaic module manufacturing.This work shows how machine vision can accelerate slow characterization steps essential for the multi-objective optimization of thin film deposition processes.

关键词： optimization perovskite film

Analysis of network instantaneous availability based on percolation theory

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Analysis of network instantaneous availability based on perc...