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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • electron-transparent membranes
  • micropump
  • field emission electron source
  • ion source
  • ion mobility spectrometry
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Wroclaw University of Science and Technology
209 条数据
?? 中文（中国） ▾

  • Vacancy defect modulation in hot-casted NiO film for efficient inverted planar perovskite solar cell

    摘要： Nickel oxide (NiOx) has exhibited great potential as an inorganic hole transport layer (HTL) in perovskite solar cells (PSCs) due to its wide optical bandgap and superior stability. In this study, we have modulated the Ni2+ vacancies in NiOx film by controlling deposition temperature in a hot-casting process, resulting the change of coordination structure and charge state of NiOx. Moreover, the change of the HOMO level of NiOx makes it more compatible with perovskite to decrease energy losses and enhance hole carrier injection efficiency. Besides, the defect modulation in the electronic structure of NiOx is beneficial for increasing the electrical conductivity and mobility, which are considered to achieve the balance of charge carrier transport and avoid charge accumulation at the interface between the perovskite and HTL effectively. Both experimental analyses and theoretical calculations reveal the increase of nickel vacancy defects change the electronic structure of NiOx by increasing the ratio of Ni3+/Ni2+ and improving the p-type characteristics. Accordingly, an optimal deposition temperature of the NiOx film at 120 °C enabled a 36.24% improvement in the power conversion efficiency compared to that deposited at room temperature (25 °C). Therefore, this work provides a facile method to manipulate the electronic structure of NiOx to improve the charge carrier transport and photovoltaic performance of related PSCs.

    关键词： Electronic structure,Vacancy,Hole transport layer,Conductivity,Energy level,Mobility

    更新于2025-09-16 10:30:52

  • A Random Polymer Donor for High-Performance Polymer Solar Cells with Efficiency Over 14%

    摘要： Constructing random copolymers has been regarded as an easy and effective approach to design polymer donors for state-of-the-art polymer solar cells (PSCs). In this work, we develop a naphtho[2,3-c]thiophene-4,9-dione (NTDO) based copolymer PBN-Cl as a donor material for PSC, and a moderate power conversion efficiency (PCE) of 11.21% is achieved with a relatively low fill factor (FF) of 0.615. We then incorporate a similar acceptor unit benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) into the polymeric backbone of PBN-Cl to tune its photovoltaic performance, and a significantly higher PCE of 14.05% is achieved from the random polymer PBN-Cl-B80 containing 80% BDD unit. The enhanced PCE of the PBN-Cl-B80-based device mainly relies on the higher FF value, resulting from the improved charge mobility properties, reduced bimolecular and trap-assisted recombination, and more appropriate phase separation. The results demonstrate a feasible strategy to tune the photovoltaic performance of polymer donors by constructing random polymer with a compatible component.

    关键词： polymer solar cells,power conversion efficiency,random polymer,fill factor,charge-carrier mobility,polymer donor

    更新于2025-09-16 10:30:52

  • Can Mobility Negative Temperature Coefficient Be Reconciled with the Hopping Character of Transport in Conducting Polymers?

    摘要： Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer that is used in a wide range of applications such as electronics, optoelectronics and bioelectronics, where the fundamental understanding of the charge transport, and in particular of the electrical conductivity σ, is a prerequisite to develop high performance devices. There are many reports in the literature where the conductivity of archetypical conducting polymer PEDOT doped with Tosylate (PEDOT:TOS) exhibits a negative temperature coefficient, dσ/dT < 0, which is strikingly different from the activated-type behavior with dσ/dT > 0 commonly observed in most conducting polymers. This unusual temperature dependence was attributed to the transition from the photon-assisted hopping to the metallic behavior, which is however difficult to rationalize taking into account that this transition occurs at high temperatures. In order to understand the origin of this unusual behavior, a multi-scale mobility calculations in PEDOT:TOS for the model of hopping transport were performed, where changes in the morphology and the density of states (DOS) with the temperature were explicitly taken into account. The morphology was calculated using the Molecular Dynamics simulations, and the hopping rates between the chains were calculated quantum-mechanically following the Miller-Abrahams formalism. Our results reproduce the observed negative temperature coefficient, where however the percolation analysis shows that this behavior mainly arises because of the changes in morphology upon heating when the system becomes less ordered. This results in a less efficient π-π stacking and hence lower mobility in the system. We therefore conclude that experimentally observed negative mobility temperature coefficient in conducting polymers at high temperatures is consistent with the hopping transport, and does not necessarily reflect the transition to a metallic band-like transport. Based on our multi-scale modeling we introduce a simple Gaussian Disorder Model for the efficient mobility calculations, where the DOS broadening is a function of the temperature, and where the transfer integrals distribution is a bimodal distribution evolving with temperature.

    关键词： PEDOT,Band transport,Hopping transport,Negative temperature coefficient,Electrical mobility,Multiscale calculation

    更新于2025-09-16 10:30:52

  • Fine-tuning of spark-discharge aerosol CVD reactor for single-walled carbon nanotube growth: the role of ex situ nucleation

    摘要： We report a development of recently designed apparatus equipped with a spark discharge generator of catalytic nanoparticles for robust aerosol CVD synthesis of single-walled carbon nanotubes. We achieve a profound control over the diameter distribution and the defectiveness of carbon nanotubes produced. By providing a justified comparison of the apparatus with the most abundant aerosol CVD reactor utilizing ferrocene as a catalyst precursor, we reveal the role of the activation procedure: while spark-discharge generator provides aerosol of nanoparticles (ex situ route), the ferrocene vapor decomposes in the nanotube growth zone providing an in situ formation of the catalyst. With other parameters being equal, we reveal the differences in the nanotube growth (diameter and length distribution, yield, defectiveness) employing a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy). We show the ex situ activation in the spark discharge reactor to provide a lower utilization degree of the nanoparticles due to over-coagulation. However, the same method provides an independence of the key performance parameters of the nanotubes opening a room for scaling the apparatus.

    关键词： spark-discharge generator,differential mobility analyzer,aerosol CVD synthesis,catalyst activation,floating catalyst,single-walled carbon nanotubes

    更新于2025-09-16 10:30:52

  • Simulation Investigation of Laterally Downscaled N-Polar GaN HEMTs

    摘要： The N-polar GaN high-electron mobility transistors (HEMTs) have demonstrated a powerful performance as the Ga-polar GaN HEMTs. This investigation aims to show the direct current performance and cutoff frequency (fT) of the planar N-polar GaN HEMTs with gate lengths downscaling from 4 μm to 50 nm by 2-D device simulation. The impacts of traps and gate dielectrics and the roles of the ?eld-dependent mobility and the source and drain series resistances are investigated. For our central-gated device with a 10-nm top GaN channel layer, a 30-nm Al0.3Ga0.7N barrier layer, and a 3-nm Al2O3 gate dielectric, the gate length (LG) as the transition point from the long-channel behavior to the short-channel one is found to be 200 nm. For LG < 200 nm, a linear fT versus LG relation shows up, and notable short-channel effects appear, i.e., the negative shift of the threshold voltage, the increase of the drain-induced barrier lowering, and the almost LG-independent constant maximum transconductance in the saturation region. The degradation of the fT × LG product with the decrease in the aspect ratio between LG and the equivalent gate-channel distance (tt) is shown to be quite small. The LG/tt ratio for 15% degradation of the fT × LG product from its upper limit (19.23 GHz · μm) is 5.5. This small degradation of the frequency characteristics in short-channel devices is attributed to the quite small fringing capacitance of the gate.

    关键词： short-channel effect,laterally scaling,N-polar GaN,High-electron mobility transistor (HEMT)

    更新于2025-09-12 10:27:22

  • Self-catalyzed growth of GaSb nanowires for high performance ultraviolet-visible-near infrared photodetectors; 自催化生长GaSb纳米线及其在高性能紫外-可见-近红外光电探测器中的应用;

    摘要： A simple self-catalyzed chemical vapor deposition process was conducted to synthesize single-crystalline GaSb nanowires, where Ga droplets were utilized as the catalysts. The as-grown GaSb nanowires exhibited typical p-type semiconductor behavior with the calculated hole mobility of about 0.042 cm2 V?1 s?1. The photoresponse properties of the GaSb nanowires were studied by fabricating nanowire photodetectors on both rigid and flexible substrates. The results revealed that the photodetectors exhibited broad spectral response ranging from ultraviolet, visible, to near-infrared region. For the device on rigid substrate, the corresponding responsivity and the detectivity were calculated to be 3.86×103 A W?1 and 3.15×1013 Jones for 500 nm light, and 7.22×102 A W?1 and 5.90×1012 Jones for 808 nm light, respectively, which were the highest value compared with those of other reported Ga1?xInxAsySb1?y structure nanowires. Besides, the flexible photodetectors not only maintained the comparable good photoresponse properties as the rigid one, but also possessed excellent mechanical flexibility and stability. This study could facilitate the understanding on the fundamental characteristics of self-catalyzed grown GaSb nanowires and the design of functional nano-optoelectronic devices based on Gasb nanowires.

    关键词： photoresponse,GaSb nanowires,chemical vapor deposition,mobility,near-infrared,flexible

    更新于2025-09-12 10:27:22

  • [IEEE 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - Paris, France (2019.9.30-2019.10.1)] 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - HEMT Small-Signal Modelling for Voltage-Controlled Attenuator Applications

    摘要： Multi-bias measured and simulated S parameters are presented to validate the extension of an accurate on/off state HEMT switch small-signal modelling procedure to analog attenuator applications. Good agreements between measured and simulated multi-bias S parameters of the HEMT with a gate resistor are achieved by using only a common-gate real test-structure (without the gate resistor), which not only confirm the validity of the modelling for both digital and analog attenuator applications, but also validate the applicability of the capacitance network and extraction methods under more bias conditions.

    关键词： small-signal model,voltage-controlled attenuator (VCA),high electron-mobility transistor (HEMT),monolithic microwave integrated circuit (MMIC)

    更新于2025-09-12 10:27:22

  • Using Deep Machine Learning to Understand the Physical Performance Bottlenecks in Novel Thin‐Film Solar Cells

    摘要： There is currently a worldwide effort to develop materials for solar energy harvesting which are efficient and cost effective, and do not emit significant levels of CO2 during manufacture. When a researcher fabricates a novel device from a novel material system, it often takes many weeks of experimental effort and data analysis to understand why any given device/material combination produces an efficient or poorly optimized cell. It therefore takes the community tens of years to transform a promising material system to a fully optimized cell ready for production (perovskites are a contemporary example). Herein, developed is a new and rapid approach to understanding device/material performance, which uses a combination of machine learning, device modeling, and experiment. Providing a set of electrical device parameters (charge carrier mobilities, recombination rates, trap densities, etc.) in a matter of seconds thus offers a fast way to directly link fabrication conditions to device/material performance, pointing a way to further and more rapid optimization of light harvesting devices. The method is demonstrated by using it to understand annealing temperature and surfactant choice and in terms of charge carrier dynamics in organic solar cells made from the P3HT:PCBM, PBTZT-stat-BDTT-8:PCBM, and PTB7:PCBM material systems.

    关键词： charge carrier mobility,machine learning,organic solar cells,thin film solar cells,drift diffusion

    更新于2025-09-12 10:27:22

  • AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Kerala, India (12–14 June 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Measurement of hole mobility in P3HT based photovoltaic cell using space charge limited current method

    摘要： Mobility of carriers is one of the pivotal parameters characterizing any semiconducting material and it is important for organic semiconductors too. The mobility of organic semiconductors remains far less when compared to inorganic counterparts and hence attempts in the direction improvise it carries tremendous significance. This paper investigates the positive charge carriers transport properties in a bulk heterojunction organic photovoltaic cell using two different Anode Buffer Layers (PEDOT:PSS and MoO3). The method of Space Charge Limited Current (SCLC) is used to compute the hole mobilities and also the values are compared. The values obtained with PEDOT:PSS and MoO3 as HTLs are 1.043x10-4 cm2 V-1S-1 and 1.357x10-4 cm2V-1S-1 respectively. It is seen that the device with higher carrier mobility exhibits better performance.

    关键词： PEDOT:PSS,hole mobility,space charge limited current,MoO3,photovoltaic cell,P3HT

    更新于2025-09-12 10:27:22

  • Control of carrier injection and transport in quantum dot light emitting diodes (QLEDs) via modulating Schottky injection barrier and carrier mobility

    摘要： Carrier injection and transport in the quantum dot (QD) layer was modulated by tuning the Schottky injection barrier and mobility of charge transport layers. The analyses indicate that stages of the J-V curve for hole injection must match with those of electron injection to achieve the charge balance in the QD layer. In addition, it was demonstrated that not only the parameters investigated but also other parameters such as charge trap density and energy levels must be considered to enhance the e?ciency of the QLEDs. With the improved charge balance in the QD layer, the current e?ciency of the quantum dot light-emitting diode display was improved from 26 to 40 cd/A.

    关键词： Schottky injection barrier,light emitting diodes,quantum dot,charge balance,carrier mobility

    更新于2025-09-12 10:27:22