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Plasmon lifetime enhancement in a bright-dark mode coupled system
摘要： Metallic nanoparticles can localize the incident light to hot spots as plasmon oscillations, where the intensity can be enhanced by up to four orders of magnitude. Even though the lifetime of plasmons is typically short, it can be increased via interactions with quantum emitters, e.g., spaser nanolasers. However, molecules can bleach in days. Here, we study the lifetime enhancement of plasmon excitations due to the coupling with longer-lifetime dark plasmon modes. We apply an analytical model based on harmonic oscillators to demonstrate that a coupled system of bright and dark plasmon modes decays more slowly than the bright mode alone. Furthermore, exact solutions of the three-dimensional Maxwell equations, i.e., finite-difference time domain, demonstrate that the lifetime of the coupled system significantly increases at the hot spot, which is not predictable by far-field response. The decay of the overall energy of such a coupled system, which can be extracted from experimental absorption measurements, is substantially different from the decay of the hot spot field. This observation enlightens the plasmonic applications in which the hot spot intensity enables the detection of the optical responses.
关键词： bright-dark mode coupling,finite-difference time domain,metallic nanoparticles,plasmon lifetime,hot spot
更新于2025-09-19 17:13:59
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Influence of Laser Intensity Fluctuation on Single-Cesium Atom Trapping Lifetime in a 1064-nm Microscopic Optical Tweezer
摘要： An optical tweezer composed of a strongly focused single-spatial-mode Gaussian beam of a red-detuned 1064-nm laser can con?ne a single-cesium (Cs) atom at the strongest point of the light intensity. We can use this for coherent manipulation of single-quantum bits and single-photon sources. The trapping lifetime of the atoms in the optical tweezers is very short due to the impact of the background atoms, the parametric heating of the optical tweezer and the residual thermal motion of the atoms. In this paper, we analyzed the in?uence of the background pressure, the trap frequency of optical tweezers and the laser intensity ?uctuation of optical tweezers on the atomic trapping lifetime. Combined with the external feedback loop based on an acousto-optical modulator (AOM), the intensity ?uctuation of the 1064-nm laser in the time domain was suppressed from ±3.360% to ±0.064%, and the suppression bandwidth in the frequency domain reached approximately 33 kHz. The trapping lifetime of a single-Cs atom in the microscopic optical tweezers was extended from 4.04 s to 6.34 s.
关键词： optical tweezer,suppression of laser intensity ?uctuation,parametric heating,atomic trapping lifetime
更新于2025-09-19 17:13:59
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Photovoltaic Module Reliability || What does the Future Hold for PV and a Brief Summary
摘要： The discussions in the previous chapters looked at both the history and present‐day status of photovoltaics (PV) module reliability and the accelerated stress testing associated with it. In this final chapter, the focus will shift to the future. PV is a dynamic industry so the technology and the testing standards are constantly evolving. The first section in this chapter will provide an update on the changes already in progress for some of the more important module qualification and safety standards. The second section will switch to a longer‐range view, discussing how PV module reliability is likely to change in the future and what sort of accelerated stress testing will be necessary to validate the quality of the huge volume of modules produced. The book will end with a brief summary of the status of PV module reliability today.
关键词： accelerated stress testing,flexible modules,IEC 61215,IEC 61730,bifacial modules,module lifetime,degradation rates,PV module reliability,photovoltaics
更新于2025-09-19 17:13:59
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Realizing Asymmetric Boundary Conditions for Plasmonic THz Wave Generation in HEMTs
摘要： As a key component in the wind turbine system, the power electronic converter and its power semiconductors suffer from complicated power loadings related to environment, and are proven to have high failure rates. Therefore, correct lifetime estimation of wind power converter is crucial for the reliability improvement and also for cost reduction of wind power technology. Unfortunately, the existing lifetime estimation methods for the power electronic converter are not yet suitable in the wind power application, because the comprehensive mission profiles are not well specified and included. Consequently, a relative more advanced approach is proposed in this paper, which is based on the loading and strength analysis of devices and takes into account different time constants of the thermal behaviors in power converter. With the established methods for loading and lifetime estimation for power devices, more detailed information of the lifetime-related performance in wind power converter can be obtained. Some experimental results are also included to validate the thermal behavior of power device under different mission profiles.
关键词： power semiconductor device,lifetime prediction,thermal cycling,wind power,IGBT,mission profiles
更新于2025-09-19 17:13:59
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Performance analysis of narrow-bandgap interband cascade thermophotovoltaic cells
摘要： We present the detailed characterization and performance analysis of two sets of four interband cascade thermophotovoltaic (TPV) devices with InAs/GaSb type-II superlattice (SL) absorbers. The bandgaps of the SL absorbers in the four devices were between 0.22 and 0.25 eV at 300 K. With different numbers of cascade stages and individual absorber thicknesses, we are able to show how possible material quality variations and current mismatch between stages can affect the device performance. Based on the calculated effective quantum efficiency in each stage and experimental results, it is shown that the current mismatch between stages due to the deviation of absorption coefficient from the designed value can be substantial with more stages. On the other hand, the collection efficiency can be much improved with more stages and thin individual absorbers. Also, the carrier lifetime is extracted through measured dark current density to evaluate the material quality. The effects of material quality, current mismatch and collection efficiency on device performance are quantified and a comparison shows that material quality plays the most important role.
关键词： Interband cascade,current mismatch,carrier lifetime,thermophotovoltaic cells
更新于2025-09-19 17:13:59
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Built-in voltage enhanced by in-situ electrochemical polymerized undoped conjugated hole-transporting modifier in organic solar cells
摘要： Herein, a new electropolymerized (EP) film named poly-triphenylcarbazole fluoranthene (p-TPCF) has been in-situ synthesized by electrochemical cyclic voltammetry method, and applied to tune the work-function (WF) of the PEDOT:PSS hole-transporting layer (HTL) in organic solar cells (OSCs). Multi techniques, including Kelvin probe force microscopy (KPFM), light intensity dependent solar cell characterization, Mott-Schottky analysis, transient photovoltage (TPV) and transient photocurrent (TPC) measurements, have been explored to provide insights into the mechanism. Benefiting from deeper work-function (WF), larger built-in voltage (Vbi), decreased recombination, longer carrier lifetime, the devices with EP film exhibited superior device performance with simultaneously enhanced Voc, Jsc and FF.
关键词： PEDOT:PSS,built-in voltage,work-function tuning,organic solar cells,carrier lifetime,electropolymerized film,charge recombination
更新于2025-09-19 17:13:59
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Prolonged Lifetime of Perovskite Solar Cells Using a Moisture-Blocked and Temperature-Controlled Encapsulation System Comprising a Phase Change Material as a Cooling Agent
摘要： Although the power conversion efficiency of perovskite solar cells (PSCs) reached up to 25% that made them comparable to the commercial solar cells, they are facing issues toward commercialization, especially their short lifetime. Remarkably, the most important key factors that regulate the durability of the devices are moisture, light, and heat. In this work, prolonging the device lifetime is focused by designing a flexible moisture-blocked and temperature-controlled encapsulation system. In this regard, a thermally adjusted phase change material is embedded in a polymer encapsulation layer to avoid the moisture diffusion, rapid temperature fluctuation, and undesired crystalline phase change of the perovskite layer in the PSCs under the operation condition. As a result, a 2 year stable device is achieved, whereas the reference device loses more than 50% of its performance after 10 days. Surprisingly, the charge transport resistance and recombination rate show no significant change during 450 days of storage, which confirms no increase in the defect density.
关键词： encapsulation system,temperature-controlled,phase change material,perovskite solar cells,lifetime,moisture-blocked
更新于2025-09-19 17:13:59
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Efficient defect passivation of perovskite solar cells via stitching organic bidentate molecule
摘要： The defects present in the solution-processed perovskite light absorbing materials are responsible for deteriorating the performance and stability of perovskite solar cells. Therefore, suppressing of the defect formation and passivating the pre-existing defects in perovskite materials is of paramount importance in pushing the efficiency of perovskite solar cell (PSC) toward the theoretical limit and ensuring the long-term stability of PSC. In this work, we report an efficient defect passivation route using a bidentate small organic molecule, pyrazine, which is capable of making either a monodentate or a bridging bidentate bonding with under-coordinated Pb2+ ions mainly present in the surface and grain-boundary of perovskite films. The various analyses for defect density and charge carrier lifetime of perovskite light absorbing layer demonstrated that the pyrazine effectively passivated defects existing on the surface and grain boundary of the perovskite films without affecting the morphology and crystallinity via a simple post-treatment procedure. As a result, the best untreated device obtained a power conversion efficiency of 19.14 %, while the efficiency of 20.58 % was achieved with pyrazine treated.
关键词： bidentate molecule,defect passivation,charge carrier lifetime,perovskite solar cells,pyrazine
更新于2025-09-19 17:13:59
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Killer impurities in vacuum chamber that affect the lifetime of organic light-emitting diodes
摘要： We have evaluated a method to investigate killer impurities in vacuum chambers that affect the lifetimes of organic light-emitting diodes (OLEDs) processed in these chambers. In addition to chambers for the deposition of organic and metal films, an exposure chamber was installed to expose the OLEDs to impurities and residual water in a vacuum chamber during device fabrication. We studied a method to investigate the effects of these vacuum chamber impurities after establishing the reproducibility of the device lifetimes. These device lifetimes were affected by the cleanliness of the exposure chamber. Increased exposure times led to shorter device lifetimes, even if the contact angle in the exposure chamber was reduced to less than 5° using plasma cleaning. Furthermore, the device lifetime did not degrade when the partial pressure of water within the exposure chamber was reduced using a cryotrap. We were also able to evaluate the Kapton tape and vacuum greases that were used and determined whether they affected the device lifetime. These results suggest that the influence of residual water and impurities can be separated and it would then be possible to evaluate the influence of the impurities alone on the device lifetime.
关键词： device lifetime,plasma cleaning,cryotrap,OLED,impurities,vacuum chamber
更新于2025-09-19 17:13:59
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - EKF Analysis For Positive Business Case: Telecom 4.0 And Modern Smart City
摘要： Consider a mobile sensor network that is used to monitor a moving target in a field with obstacles. In this paper, an efficient relocation technique that simultaneously maximizes the network lifetime is proposed. The main sources of energy consumption in the network are sensing, communication, and movement of the sensors. To account for this energy consumption, a graph is constructed with edges that are weighted based on the remaining energy of each sensor. This graph is subsequently employed to address the lifetime maximization problem by solving a sequence of shortest path problems. The proposed technique determines a near-optimal relocation strategy for the sensors as well as an energy-efficient route to transfer information from the target to destination. This near-optimal solution is calculated in every time instant using the information obtained through the previous time step. It is shown that by choosing appropriate parameters, sensors’ locations and the communication route from target to destination can be arbitrarily close to their corresponding optimal choices at each time instant. Simulation results confirm the effectiveness of the proposed technique.
关键词： target monitoring,mobile sensor network,Energy,lifetime
更新于2025-09-19 17:13:59