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High-Efficiency Perovskite Solar Cells Enabled by Anatase TiO2 Nanopyramid Arrays with Oriented Electric Field
摘要： One-dimensional (1D) nanostructured oxides have been proposed as excellent electron transport materials (ETMs) for perovskite solar cells (PSCs), but this has not yet been demonstrated experimentally. Here, we exploit a facile hydrothermal approach to grow highly oriented anatase TiO2 nanopyramid arrays and further demonstrate their advantages for application in PSCs. The oriented TiO2 nanopyramid arrays afford sufficient contact area for electron extraction and increase light transmission. Moreover, the nanopyramid array/perovskite system exhibits an oriented electric field that can increase charge separation and accelerate charge transport, thereby suppressing charge recombination. As a result, the anatase TiO2 nanopyramid arrays-PSCs deliver a champion power conversion efficiency of ~22.5%, which is the highest PCE reported thus far for PSCs consisting of 1D ETMs. This work demonstrates that the rational design of 1D ETMs can achieve PSCs that perform as well as typical mesoscopic and planar PSCs.
关键词： Anatase TiO2,Electric field distribution,Perovskite solar cells,One-dimensional nanostructures,Nanopyramid arrays
更新于2025-09-23 15:19:57
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Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution
摘要： Photoelectron emission from solids, as driven by high-intensity lasers, offers a platform for the coherent control of electron motion on ultrashort spatiotemporal scales. By solving the time-dependent Schr?dinger equation, we present an exact analytical solution for the nonlinear ultrafast electron emission from a dc-biased metal surface illuminated by two-color laser fields. We systematically examine the combined effects of a dc electric field and two-color laser fields. In addition to the remarkable tunability of electron emission processes due to interference from two-color laser fields, we find that a strong dc electric field not only opens up more tunneling emission channels, but also introduces intense modulation to the emission current. We find surprising results that strong current modulation (with respect to the phase difference of the two-color lasers) persists (>70%), even with a large dc bias (i.e., ratio of the electric fields for dc : fundamental laser : second-harmonic laser ～= 1 : 0.5 : 0.07). In the meantime, the average emission current level increases by about three orders of magnitude relative to the case of zero dc bias. Application of our model to time-resolved photoelectron spectroscopy is exemplified and shows that the dynamics of the n-photon excited states depends strongly on the applied dc field. Our study suggests a practical way to maintain a strong modulation to high current photoemission, by the addition of a large dc bias for two-color laser-induced electron emission.
关键词： dc electric field,two-color laser fields,ultrafast electron emission,photoelectron emission,time-dependent Schr?dinger equation
更新于2025-09-23 15:19:57
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Toward reliable high performing organic solar cells: Molecules, processing, and monitoring
摘要： A steady surge in device efficiencies of organic solar cells (OSCs) along with improvement in associated features, such as stability and facile processing methods, is expected to provide a realistic, feasible commercial option. The introduction of high performing donor and acceptor molecules along with tailored buffer layers has provided the impetus for the resurgence of this field. Further options of ternary and tandem architectures of these OSC systems should push this technology to competitive levels. A major hurdle, which is expected when these devices are evaluated for long-term performance in all weather conditions, is the level of degradation. We examine and address these stability-limiting factors in this perspective article. Modifications in microstructure/morphology and interfaces with time and energy levels defining the molecules form some of the critical intrinsic degradation pathways. Various strategies that have been used to limit the associated pathways of degradation of the active layer will be discussed. One such strategy is electric field-assisted thermal annealing treatment, which concomitantly also brings in a favorable vertical phase segregated active layer morphology. We also emphasize the utility of photocurrent noise measurements to monitor the level of degradation and possibly forecast the trajectory of long-term performance of OSCs.
关键词： processing methods,photocurrent noise measurements,electric field-assisted thermal annealing,device efficiencies,degradation,donor and acceptor molecules,organic solar cells,stability,ternary and tandem architectures
更新于2025-09-23 15:19:57
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Effect of Horizontal p-n Junction on Optoelectronics Characteristics in InGaN-Based Light-Emitting Diodes with V-shaped Pits
摘要： Two InGaN-based light-emitting diodes (LEDs) with and without pre-layer were prepared, and both had a similar multi-quantum well (MQW) structure with four green QWs near n-GaN and one blue QW close to p-GaN. The pre-layer established large V-shaped pits in MQWs. In addition to the regular vertical p-n junction along c-axis, a kind of horizontal p-n junction created by n-type MQWs and p-GaN filled in V-shaped pits was introduced. And the effect of the horizontal p-n junction on optoelectronics characteristics, including photoluminescence, electroluminescence, and ??-??, were discussed. The horizontal p-n junction creates a strong horizontal built-in electric field which can effectively separate the photogenerated carriers in the QW close to p-GaN, leading to the absence of photoluminescence from the QW close to p-GaN. The horizontal p-n junction also provides a path for hole injection, which changes the turn-on order of QW, and reduces the voltage of the LED with large V-shaped pits. These results suggest a new thought of analyzing and designing InGaN-based LEDs with V-shaped pits.
关键词： light-emitting diode,V-shaped pit,indium gallium nitride,built-in electric field
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Generation of particles during laser treating of metal in external electric field
摘要： It is shown that in the course of laser processing with radiation flux density ～106 W/cm–2 in the external electric field with different polarity varying from 0 to 106 V/m-1 the change in the evolution features of the plasma torch at the surface of some metals (Cu, Al, Pb) at early stages is quantitative rather than qualitative. At the same time the characteristic size of the target material droplets carried out from the irradiated zone, becomes by several times smaller as the amplitude of the external electric field strength grows, independently of its polarity.
关键词： laser radiation,electric field,gravitycapillary waves,plasma formation
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Formation of Space Charge Wave with Wide Frequency Spectrum in Helical Electron Beam of Two-Stream FEL Transit Section with Longitudinal Electric Field
摘要： The longitudinal electric field effect on the formation of a space charge wave (SCW) with wide frequency spectrum in the helical two-stream relativistic electron beam (REB), which moves in transit section of multiharmonic two-stream superheterodyne free-electron laser, is analyzed. In the framework of cubic nonlinear approximation, it is shown that the use of the accelerating electric field makes it possible to increase the multiharmonic SCW width of the frequency spectrum. It is shown that the retarding electric field causes the increase of the amplitude level SCW harmonics, as well as the decrease of its saturation length.
关键词： three-wave parametric resonance,helical electron beam,two-stream instability,two-stream superheterodyne free-electron laser,longitudinal electric field
更新于2025-09-23 15:19:57
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[IEEE 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Chennai, India (2019.8.21-2019.8.23)] 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Efficient Electron Carrier distribution of n+ MoS <sub/>2</sub> /i-MoS <sub/>2</sub> /p-Si Heterojunction Solar Cell
摘要： In this paper, modeling and simulation study of energy harvested nano electronics of PV device and its functions under different light intensity have been discussed. The emitter layer of the proposed solar cell has been designed to enhance the photocurrent efficiency even at low electric field. The Electron-hole pair generation of the proposed model is increased to 4.9*1028 [1/ (m2*s)] due to optimized intrinsic MoS2 layer thickness. As a result, the charge carriers distribution enhanced the carrier collection efficiency in the absorber layer. This study reveals that the proposed Energy harvesting device Open-circuit Voltage(Voc) and Short circuit Current density(Jsc) are 1.982[V], 31.22[mA/cm2] respectively and its efficiency found to be 31.91 %. These simulations showed that can be environmental stability and excellent carrier distribution solar cell.
关键词： electric field,efficiency-region,charge-carrier recombination,Photogeneration,n+MoS2
更新于2025-09-23 15:19:57
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Electric field-directed assembly of fullerene crystal rods into hierarchical films
摘要： Self-assembly of nanomaterials with desired material properties requires assembly control from nanometer to millimeter scales. Here, hierarchical C60 and C70 films are assembled from the nanoscale to macroscale by combining co-solvent precipitation with electric-field directed assembly. Fullerene molecular crystals are grown via seeded co-solvent precipitation with mixed organic solvents and antisolvent 2-propanol. Rods of varying aspect ratios (1.7, 2 and 3.7) are prepared as a function of injection volume, fullerene type and solution concentration. Electric fields are applied to colloidal fullerene rods confined to two dimensions. The applied field induces dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency-dependent phase transitions occur at the critical Maxwell–Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced, resulting in changes in structure. Partial order phases form as a function of field strength, frequency, and confinement including tetratic, smectic, centered rectangular and string fluids.
关键词： colloidal rods,electric field,fullerene,hierarchical films,self-assembly
更新于2025-09-19 17:15:36
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Estimation of the Lyman- <i>α</i> signal of the EFILE diagnostic under static or radiofrequency electric field in vacuum
摘要： The electric field induced Lyman-α emission diagnostic aims to provide a non intrusive and precise measurement of the electric field in plasma, using a beam of hydrogen atoms prepared in the metastable 2s state. The metastable particles are obtained by means of a proton beam extracted from a hydrogen plasma source, and neutralised by interaction with vaporised caesium. When a 2s atom enters a region where an electric field is present, it undergoes a transition to the 2p state (Stark mixing). It then quickly decays to the ground level, emitting Lyman-α radiation, which is collected by a photomultiplier. The s→p transition rate is proportional to the square of the magnitude of the electric field, and depends on the field oscillation frequency (with peaks around 1 GHz). By measuring the intensity of the Lyman-α radiation emitted by the beam it is possible to determine the magnitude of the field in a defined region. In this work, an analysis of the behaviour of the diagnostic under static or radiofrequency electric field is presented. Electric field simulations obtained with a finite element solver of Maxwell equations, combined with theoretical calculations of the Stark mixing transition rate, are used to develop a model for the interpretation of photomultiplier data. This method shows good agreement with experimental results for the static field case, and allows to measure the field magnitude for the oscillating case.
关键词： Stark effect,plasma diagnostics,electric field measurement,electromagnetic simulations
更新于2025-09-19 17:15:36
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Generalized Rayleigh surface waves in a piezoelectric semiconductor half space
摘要： In this paper, plane strain surface waves, also named generalized Rayleigh surface waves, in a transversely isotropic piezoelectric semiconductor half space are investigated. The governing equations of generalized Rayleigh surface waves include the equations of motion, Gauss’ law of electrostatics and the conservation of charge. Based on the basic theory of elastic-dynamic equations, the governing equations are deduced as equations related to the displacement, the electric potential and the perturbation of the carrier density and are solved analytically. We discuss dispersion curves and the attenuation tendency of generalized Rayleigh waves for real wave number cases. The results reveal that the semiconductor should lead to phase velocity decreasing, and the anomalous dispersion and damping of generalized Rayleigh waves. However, enough in-plane biasing electric field along the wave propagation should lead to the amplification of the waves. The influence of the out-plane biasing electric field is so slight that it can be omitted. These properties should be reproduced in the case of real frequencies. The results obtained may provide theoretical guidance for the design of high-performance surface acoustic wave devices made of piezoelectric semiconductors.
关键词： Damping,Piezoelectric semiconductor,Generalized Rayleigh surface,Biasing electric field
更新于2025-09-19 17:15:36