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rGO based photo-anode in dye-sensitized solar cells (DSSC) and its photovoltaic characteristics
摘要： On the attempt to increase transport properties of the photo-anode in DSSC, we synthesized rGO powder from graphite bar (commercially available) using modified Hummer’s method. The SEM-EDS results had confirmed the attachment of the rGO layer to the FTO substrate. For DSSC cells, we made two cells configuration, the first one was stacking layers of rGO and TiO2 resulting configuration of TiO2/rGO/ TiO2 (A2) and rGO/TiO2/rGO (A3), where rGO was deposited by spin coating and TiO2 was deposited by a screen printing technique. The second one, the rGO powder was mixed with TiO2 paste with several ratios in weight, namely TiO2:rGO 40:1 (B1), 40:2 (B2), and 40:8 (B3) and then deposited on the FTO substrate by screen printing. The reference cell was assigned as A1 (TiO2 only). From the conductivity measurement using the four-probe method, the utilization of rGO layer increased the conductivity of photo-anode layer, namely (1.37, 2.9 and 6.3)x10-2 Ω-1cm-1 for A1 to A3 and (1.5, 2.5, and 3.7)x10-2 Ω-1cm-1 for B1 to B3. From the photovoltaic measurement, we found that the efficiency of the DSSC cell firstly increased with the insertion of rGO layer, from 1.8% (A1) to 4.59% (A2), and decreased to 3.22%, as the conductivity increased in A3. While for the composite of TiO2:rGO, the efficiency of the cell reduced with the increased amount of rGO, from 3.45% (B1) to 2.9% and 1.9% for B2 and B3. We found that the reduction of photovoltaic performance was affected by two main factors, specifically, direct contact between rGO and redox species in the electrolyte, which induced recombination process, and conductivity of the photo-anode layer. To fully achieve the advantage of rGO utilization in photo-anode, once must be considered was the use of protection layer on top of the rGO layer to avoid direct contact between the rGO/electrolyte interface.
关键词： photovoltaic,rGO,efficiency,photo-anode,DSSC,conductivity
更新于2025-09-23 15:21:01
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Exploiting ternary blends for improved photostability in high efficiency organic solar cells
摘要： Ternary organic solar cells based on polymer donor and nonfullerene acceptors (NFAs) are delivering high power conversion efficiencies (PCE). Now, further improvement needs to be directed to enhance the operational lifetime of organic photovoltaics. Here, we selected three NFAs with different electron affinities and structural properties and found that the most crystalline third component, O-IDTBR, is selectively miscible within the acceptor phase. This reduced trap-assisted recombination and delivered a PCE of 16.6% and a fill factor of 0.76, compared to PM6:Y6 binary devices (15.2% PCE). Charge transport and recombination analyses revealed that O-IDTBR acts as a charge relay for improved charge transfer of both donor and acceptor materials leading to a more ordered transport. We find that minimizing traps formation in ternary devices deactivates light-induced traps upon full sun illumination (AM1.5G). As a result, ternary devices do not show any PCE drop in 225h, in comparison to binary cells which lose more than 60% of their initial performances.
关键词： photostability,nonfullerene acceptors,ternary organic solar cells,power conversion efficiency,charge transport
更新于2025-09-23 15:21:01
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[IEEE 2020 Systems of Signals Generating and Processing in the Field of on Board Communications - Moscow, Russia (2020.3.19-2020.3.20)] 2020 Systems of Signals Generating and Processing in the Field of on Board Communications - Spectral Efficiency and Information Transfer Rate Over Optical Fibers in Spatial Parallelism
摘要： Spatial parallelism contribution to optical fibers spectral efficiency and to signal transfer rate is being estimated. Parallelism multiplier system parameter is introduced. Using this parameter analytical expressions are constructed to determine the optical fibers spectral efficiency and information transfer rate. Examples of spatial parallelism of optical signal transmission in few-mode and multicore fibers are given.
关键词： spatial parallelism,information transfer rate,optical fiber,spectral efficiency,parallelism multiplier
更新于2025-09-23 15:21:01
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Improving the out-coupling efficiency of polymer light-emitting diodes with soft nanoimprinted random corrugated structures
摘要： A simple method is demonstrated in this study by applying random corrugated structures into the polymer emitting layer via soft nanoimprint technology to enhance the light out-coupling efficiency of polymer light-emitting diodes (PLEDs). The device with the random corrugated structures presents high efficiency and stable emission close to the Lambertian pattern. Compared with the flat device, about 52% efficiency enhancement is achieved in the PLEDs with the random corrugated structures, which can be understood by extraction of waveguide mode and surface plasmon polariton mode losses simultaneously. With these advantages, the simple random corrugated structures have the potential to stimulate the development of low-cost and large-area flexible PLEDs with high efficiency in the applications of solid-state light sources and full-color displays.
关键词： surface plasmon polariton mode,soft nanoimprint,light out-coupling efficiency,random corrugated structures,polymer light-emitting diodes,waveguide mode
更新于2025-09-23 15:21:01
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Suggestions on Efficiency Droop of GaN-based LEDs
摘要： InGaN/GaN-based light-emitting diodes (LEDs) are widely used in modern society and industry among different areas. However, InGaN/GaN LEDs suffer from an efficiency droop issue: The internal efficiency decreases during high current injection. The efficiency droop significantly affects the development of GaN-based LEDs devices in efficiency and light-output areas. Therefore, the improvement of the droop phenomenon has become a significant topic. This paper introduces several possible mechanisms of droop phenomenon based on different hypotheses including Auger Recombination, Carrier Delocalization and Electron Leakage. Furthermore, some proposals to mitigate efficiency droop, including semipolar LEDs, electron blocking layer(EBL), quaternary alloy and chip design will be discussed and analyzed. Also, it will provide some suggestions for the further optimization of droop phenomenon in each proposal.
关键词： electron blocking layer,semipolar LEDs,GaN-based LEDs,Auger Recombination,chip design,quaternary alloy,Carrier Delocalization,Electron Leakage,efficiency droop
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 9th International Conference on Consumer Electronics (ICCE-Berlin) - Berlin, Germany (2019.9.8-2019.9.11)] 2019 IEEE 9th International Conference on Consumer Electronics (ICCE-Berlin) - Case Study of Photovoltaic Energy Surplus Absorption by Charging Lithium-Ion Batteries Considering Chargea??Discharge Energy Efficiency
摘要： In Autumn 2018, reductive control of photovoltaic surplus energy was performed in Kyushu, Japan. This was a lost opportunity to utilize renewable energy, which could have been otherwise stored in rechargeable batteries. In this study, we simulated the absorption of the photovoltaic energy surplus by charging battery systems of a working electric vehicle considering the energy efficiency of lithium-ion battery systems to reduce the operation cost. This study clarified the quantitative effects of a real-time energy efficiency diagnosis of lithium-ion battery systems. From the simulation results, we discovered that the improvements of the charge–discharge energy loss and the economic gain of the photovoltaic energy surplus absorption depended on the input–output power of the bidirectional vehicle- to-grid charger and the amount of surplus energy. When the input–output power is sufficiently high and the ratio of surplus energy to total capacity of the battery systems is sufficiently low, is the reasonable. The real-time degradation diagnosis of the battery systems and selection considering charge–discharge energy efficiency is necessary to improve the profit from surplus energy absorption.
关键词： charge – discharge energy efficiency,Lithium-ion battery,degradation diagnosis,photovoltaic surplus energy,working electric vehicle
更新于2025-09-23 15:21:01
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - GLRT Detectors for Airborne Radar Based on Knowledge-Aided and Compressive Sensing
摘要： The influences of the intermediate band (IB) filling, the absorption coefficient constants, and the IB position on the efficiency of a quantum dot intermediate band solar cell (QD-IBSC) are investigated considering the spatial variation of subbandgap generation rates. A new definition of optimal intermediate band filling is proposed. A mathematical model is developed to optimize the intermediate band solar cell (IBSC) structure under idealized conditions, which calculates the optimal ratio of the subbandgap absorption coefficient constants and the optimal position of IB.
关键词： optimal filling,conversion efficiency,Intermediate band solar cell (IBSC),IB position,absorption coefficients
更新于2025-09-23 15:21:01
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Numerical studies of metal particle behaviors inside the selective laser melting (SLM) chamber through computational fluid dynamics (CFD)
摘要： The flow behavior of the shielding gas has been a key factor to improve the quality of products manufactured by the selective laser melting (SLM) technology as it is a major mechanism to remove the ejected metal particles away from the working plane. In this study, to obtain a proper flow field, computational fluid dynamics (CFD) with the application of the Taguchi method was employed to investigate the flow field across the working chamber, with the variations in the geometries of the blowing nozzle, the widths of the suction tunnel, the suction-to-plane distances, and the Reynolds numbers of the blowing flow. The simulation was first verified with experimental measurements. The ejecting motions of the metal powders were also taken into consideration to study the interactions between the shielding gas and the ejected particles. The results demonstrated that axis switching as well as the suction-to-plane distance are the important factors for improving the particle removal efficiency during the SLM operation.
关键词： Selective laser melting,Computational fluid dynamics,Particle removal efficiency,3-D printing,Axis switching,Taguchi method
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Study of Self-assembled 2D Ag Nanostructures Intercalated into In <sub/>4</sub> Se <sub/>3</sub> Layered Semiconductor Crystal
摘要： This paper presents an advanced depth intra-coding approach for 3D video coding based on the High Efficiency Video Coding (HEVC) standard and the multiview video plus depth (MVD) representation. This paper is motivated by the fact that depth signals have specific characteristics that differ from those of natural signals, i.e., camera-view video. Our approach replaces conventional intra-picture coding for the depth component, targeting a consistent and efficient support of 3D video applications that utilize depth maps or polygon meshes or both, with a high depth coding efficiency in terms of minimal artifacts in rendered views and meshes with a minimal number of triangles for a given bit rate. For this purpose, we introduce intra-picture prediction modes based on geometric primitives along with a residual coding method in the spatial domain, substituting conventional intra-prediction modes and transform coding, respectively. The results show that our solution achieves the same quality of rendered or synthesized views with about the same bit rate as MVD coding with the 3D video extension of HEVC (3D-HEVC) for high-quality depth maps and with about 8% less overall bit rate as with 3D-HEVC without the combination of related depth tools. At the same time, the combination of 3D video with 3D computer graphics content is substantially simplified, as the geometry-based depth intra signals can be represented as a surface mesh with about 85% less triangles, generated directly in the decoding process as an alternative decoder output.
关键词： 3D video coding,High Efficiency Video Coding (HEVC),multiview video plus depth (MVD),depth intra coding,wedgelets,mesh extraction,inter component prediction,3D video extension of HEVC (3D-HEVC)
更新于2025-09-23 15:21:01
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Roll-to-Roll Slot-Die Coated P-I-N Perovskite Solar Cells Using Acetonitrile Based Single Step Perovskite Solvent System
摘要： Roll-to-roll coating of all active layers is demonstrated for a P-I-N perovskite solar cell stack, using a single step perovskite ink with an acetonitrile solvent system and flexible plastic substrate. A slot-die coating roll-to-roll process (with a common coating speed for all layers) is developed by using appropriate length meniscus guides as part of the coating head for each ink rheology. High performance devices are demonstrated with four roll-to-roll slot-die coated layers and evaporated top electrode. The drying conditions of the perovskite layer are optimized and found to be critical to achieving good performance. Multi solvent blend systems for the electron collection layer are developed that are more industrially compatible than the commonly used chlorobenzene solvent system and make use of a gradient of solvent volatilities to give both good macro film formation and rapid drying. A stabilised power conversion efficiency of 12.2% is demonstrated, that is the highest reported to date for devices with all layers other than the top electrode deposited roll-to-roll. This work demonstrates the feasibility of a roll-to-roll fabrication process for perovskite solar cells that could be transferred to a fully inline roll-to-roll process with all coating and drying stages made sequentially on one line running at a common coating speed and further demonstrates the potential to produce high efficiency photovoltaics using roll-to-roll fabrication methods.
关键词： Stabilised power conversion efficiency,Perovskite solar cells,Slot-die coating,Roll-to-roll,Acetonitrile solvent system
更新于2025-09-23 15:21:01