- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Photovoltaic Solar Cells for Outdoor LiFi Communications
摘要： Most state-of-the-art methods in pedestrian detection are unable to achieve a good trade-off between accuracy and efficiency. For example, ACF has a fast speed but a relatively low detection rate, while checkerboards have a high detection rate but a slow speed. Inspired by some simple inherent attributes of pedestrians (i.e., appearance constancy and shape symmetry), we propose two new types of non-neighboring features: side-inner difference features (SIDF) and symmetrical similarity features (SSFs). SIDF can characterize the difference between the background and pedestrian and the difference between the pedestrian contour and its inner part. SSF can capture the symmetrical similarity of pedestrian shape. However, it for neighboring features to have such above characterization abilities. Finally, we propose to combine both non-neighboring features and neighboring features for pedestrian detection. It is found that non-neighboring features can further decrease the log-average miss rate by 4.44%. The relationship between our proposed method and some state-of-the-art methods is also given. Experimental results on INRIA, Caltech, and KITTI data sets demonstrate the effectiveness and efficiency of the proposed method. Compared with the state-of-the-art methods without using CNN, our method achieves the best detection performance on Caltech, outperforming the second best method (i.e., checkerboards) by 2.27%. Using the new annotations of Caltech, it can achieve 11.87% miss rate, which outperforms other methods.
关键词： feature extraction,non-neighboring features,Pedestrian detection,neighboring features,adaboost
更新于2025-09-23 15:19:57
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The diverse passivation effects of fullerene derivative on hysteresis behavior for normal and inverted perovskite solar cells
摘要： [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is usually used to passivate the trap states and ion defects for suppressing hysteresis in both normal and inverted perovskite solar cells. Here, we find that the normal cell with the perovskite film fabricated on the PCBM film shows an evident hysteresis, while the inverted cell with the perovskite film covered by the PCBM film shows nearly no hysteresis, and the PCBM-Perovskite interface impacts on the hysteresis vastly. The poor PCBM surface wettability results in an inefficient carrier extraction at the interface and a red-shift of photoluminescence emission for the perovskite film coated on the PCBM film, which results from the plentiful trap states and ion defects inside the perovskite film due to its poor crystallization. Thus, the trapping/de-trapping processes and slow ion migration eventually lead to the hysteresis. For the perovskite film covered by the PCBM film, due to the good wettability of the perovskite film, PCBM molecules easily permeate into the perovskite film to passivate the trap states and ion defects, which improves the carrier extraction and thus eliminates the hysteresis of the inverted cell.
关键词： Hysteresis behavior,Trap states,Perovskite solar cells,Ion migration,Carrier extraction,PCBM
更新于2025-09-23 15:19:57
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Highly Efficient Tandem White OLED Using a Hollow Structure
摘要： A simple fabrication method for a light extraction layer is required. In this report, an internal light extraction layer composed of a high refractive index material and an air void is fabricated in five steps. A direct printing process followed by annealing of the randomly arrayed poly(benzyl methacrylate) pillars after a planarization process using TiO2-nanoparticle dispersed resist and sol is used. These substrates are used for light extraction in white tandem organic light emitting diodes (WOLEDs). By combining the hollow structure and hemi-spherical lens, WOLEDs without and with the light extraction structures are found to show maximum external quantum efficiencies of 35.6% and 103%, respectively. The power efficiencies at 100 cd m?2 of the WOLEDs without and with the light extraction structures are found to be 26.5 and 93.2 lm W?1, respectively. A color rendering index of 86.4, correlated color temperature of 4860 K, and CIE of (0.353, 0.389) are achieved in the WOLEDs with light extraction structures.
关键词： organic light emitting diodes,high refractive index,light extraction efficiency,nanoimprint lithography,light scattering layers
更新于2025-09-23 15:19:57
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Extraction of the terahertz constitutive tensors of multilayer graphene-dielectric stacks
摘要： In this paper, we present a reliable method to extract the electromagnetic constitutive tensors of complex synthesized multilayer graphene-dielectric stacks in the terahertz band. This macroscopic electromagnetic characterization method uses the transmission and reflection coefficients of a normal-incident circularly polarized electromagnetic wave on the material structure. The employment of circularly polarized waves has the advantage of overcoming the ambiguity at high frequencies attributed to the multi-branching discontinuities in the extracted permeability and permittivity tensors of natural or synthesized materials. The retrieved permeability and permittivity tensors are validated by the data obtained from analytical and numerical solutions of the original electromagnetic problem for the case of circularly polarized wave incidence.
关键词： Graphene-dielectric,Terahertz,Tensor extraction,Effective medium theory,Circular polarization
更新于2025-09-23 15:19:57
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Inorganic molecule-induced electron transfer complex for highly efficient organic solar cells
摘要： Interfacial engineering of electrode modification has been proved to be an effective approach for improving the power conversion efficiency (PCE) of organic solar cells (OSCs). However, compared to the advance in active layer, the study of interfacial modification is seriously lagging behind and the contribution of electrode modification to the PCE enhancement is marginalized. Herein, we synthesized a series of polynuclear metal-oxo clusters (PMCs) with gradually varied chemical composition and photoelectronic properties, by which an efficient and stable hole extraction layer was developed to enhance OSC efficiencies. The PCE of the OSC modified by PMC-4 was improved from 15.7% to 16.3% as compared to the PEDOT:PSS device. Moreover, PMC-4 can be fabricated through solution processing without any post-treatment, and the corresponding device shows improved long-term stability. As revealed for the first time, the strong oxidizing property of PMC can induce the formation of inorganic-organic electron transfer complex with a barrier-free interface for efficient hole extraction. Furthermore, experimental data and theoretical calculation results reveal that the molecular polarization of mixed-addenda PMCs can enhance the capacitance at the AIL/active layer interfaces. As a result, the mixed-addenda PMCs can be processed by blade-coating to make a large-area OSC of 1 cm2, and a certified PCE of 14.3% was achieved.
关键词： power conversion efficiency,hole extraction layer,polynuclear metal-oxo clusters,organic solar cells,interfacial engineering
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Zhenjiang, China (2019.8.4-2019.8.8)] 2019 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - A Novel Architecture with Low Laser Power Based on Optical Networks-on-Chip
摘要： With the applications heterogeneous of Internet of Things (IoT) technology, the heterogeneous IoT systems generate a large number of heterogeneous datas, including videos and images. How to efficiently represent these images is an important and challenging task. As a local descriptor, the texton analysis has attracted wide attentions in the field of image processing. A variety of texton-based methods have been proposed in the past few years, which have achieved excellent performance. But, there still exists some problems to be solved, especially, it is difficult to describe the images with complex scenes from IoT. To address this problem, this paper proposes a multi-feature representation method called diagonal structure descriptor. It is more suitable for intermediate feature extraction and conducive to multi-feature fusion. Based on visual attention mechanism, five kinds of diagonal structure textons are defined by the color differences of diagonal pixels. Then, four types of visual features are extracted from the mapping sub-graphs and integrated into 1-D vector. Various experiments on three Corel-datasets demonstrate that the proposed method performs better than several state-of-the-art methods.
关键词： feature extraction,image representation,Internet of Things,image retrieval,local descriptor
更新于2025-09-23 15:19:57
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[IEEE 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) - New Delhi, India (2019.3.9-2019.3.15)] 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) - Physics based Device Modeling of GaN High Electron Mobility Transistor (HEMT) for Terahertz Applications
摘要： Scanning laser ophthalmoscopes (SLOs) can be used for early detection of retinal diseases. With the advent of latest screening technology, the advantage of using SLO is its wide field of view, which can image a large part of the retina for better diagnosis of the retinal diseases. On the other hand, during the imaging process, artefacts such as eyelashes and eyelids are also imaged along with the retinal area. This brings a big challenge on how to exclude these artefacts. In this paper, we propose a novel approach to automatically extract out true retinal area from an SLO image based on image processing and machine learning approaches. To reduce the complexity of image processing tasks and provide a convenient primitive image pattern, we have grouped pixels into different regions based on the regional size and compactness, called superpixels. The framework then calculates image based features reflecting textural and structural information and classifies between retinal area and artefacts. The experimental evaluation results have shown good performance with an overall accuracy of 92%.
关键词： retinal artefacts extraction,Feature selection,retinal image analysis,scanning laser ophthalmoscope (SLO)
更新于2025-09-23 15:19:57
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With PBDB-T as the Donor, the PCE of Non-Fullerene Organic Solar Cells Based on Small Molecule INTIC Increased by 52.4%
摘要： At present, most high-performance non-fullerene materials are centered on fused rings. With the increase in the number of fused rings, production costs and production difficulties increase. Compared with other non-fullerenes, small molecule INTIC has the advantages of easy synthesis and strong and wide infrared absorption. According to our previous report, the maximum power conversion efficiency (PCE) of an organic solar cell using PTB7-Th:INTIC as the active layer was 7.27%. In this work, other polymers, PTB7, PBDB-T and PBDB-T-2F, as the donor materials, with INTIC as the acceptor, are selected to fabricate cells with the same structure to optimize their photovoltaic performance. The experimental results show that the optimal PCE of PBDB-T:INTIC based organic solar cells is 11.08%, which, thanks to the open voltage (VOC) increases from 0.80 V to 0.84 V, the short circuit current (JSC) increases from 15.32 mA/cm2 to 19.42 mA/cm2 and the fill factor (FF) increases from 60.08% to 67.89%, then a 52.4% improvement in PCE is the result, compared with the devices based on PTB7-Th:INTIC. This is because the PBDB-T:INTIC system has better carrier dissociation and extraction, carrier transportation and higher carrier mobility.
关键词： polymer solar cells (PSCs),synthesize easily,carrier transportation and extraction,carrier mobility,strong and wide infrared absorption,non-fullerene small molecule acceptor
更新于2025-09-23 15:19:57
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Interfacing green synthesized flake like-ZnO onto TiO <sub/>2</sub> as a bilayer electron extraction for efficient perovskite solar cells
摘要： To improve the performance of the PSCs, it is essential to prevent the carrier recombination losses at the interfaces of the transparent metal oxide electrode/electron transport layer (ETL) / active absorber perovskite layer. This present work reports about the green synthesis approach used for the preparation of flake like-ZnO nanostructure (GF-ZnO NSs), naturally extracted from the leaf of Albizia Amara - as a reducing cum capping agent. Herein, we have introduced the above prepared an n-type GF-ZnO NSs material as efficient electron transport interfacial layer (bi-ETL) at the ETL/perovskite junction in the fabricated perovskite solar cells (PSCs). The structure of the fabricated PSC device as follow: Glass/ITO/bi-ETL (c-TiO2/GF-ZnO NSs)/CH3NH3PbI3-xClx/Spiro-MeOTAD/Au. A comparative study has also been made by deploying electron transport materials such as c-TiO2 and GF-ZnO NSs separately. From this, it has been found that the bi-ETL perovskite solar cell devices achieved a maximum power conversion efficiency (PCE) of 7.83% with open-circuit voltage (VOC) of 0.728 V, short circuit current density (JSC) of 20.46 mA/cm2 and a fill factor (FF) of 52.61% compared to that of the chemically reduced ZnO based devices. Whereas, the c-TiO2, GF-ZnO NSs and the chemically reduced CR-ZnO based ETL based devices achieved a PCE of 4.84%, 5.82% and 6.81% respectively. The obtained better performance of the bi-ETL based devices is ascribed to the enhanced carrier extraction and the reduced recombination losses at the interface between the ETL and the active perovskite layer.
关键词： bilayer electron extraction,green synthesis,Perovskite solar cells,Interfacial layer,ZnO nanostructure,Albizia Amara leaf extract
更新于2025-09-23 15:19:57
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Light extraction from quantum dot light emitting diodes by multiscale nanostructures
摘要： Improving the light extraction efficiency by introducing optical–functional structures outside of quantum dot light emitting diodes (QLED) for further enhancing the external quantum efficiency (EQE) is essential for its application in display and lighting industrialization. Although the efficiency of QLED has been optimized by controlling of the synthesis of the quantum dots, the low outcoupling efficiency is indeed unresolved because of total internal reflections, waveguides and metal surface absorptions within the device. Here, we are utilizing multiscale nanostructures attaching to the outer surface of the glass substrate to extract the trapped light from the emitting layers of QLED. The result indicates that both the EQE and luminance are improved from 12.29% to 17.94% and 122400 cd m-2 to 178700 cd m-2, respectively. The maximum EQE and current efficiency improve to 21.3% and 88.3 cd A?1, respectively, which are the best performance among reported green QLED with light outcoupling nanostructures. The improved performance is ascribed to eliminate total internal reflection by multiscale nanostructures attached to the outer surface of the QLED. Additionally, the simulation result of Finite-difference time domain (FDTD) also demonstrates the light trapping effect is reduced by the multiscale nanostructures. The design of the novel light outcoupling nanostructure for further improving the efficiency of QLED can promote its application in display and lighting industrializations.
关键词： quantum dot light emitting diodes,multiscale nanostructures,light extraction efficiency,external quantum efficiency,display and lighting industrialization
更新于2025-09-23 15:19:57