- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Improved Efficiency of All-Inorganic Quantum-Dot Light-Emitting Diodes via Interface Engineering
摘要： As the charge transport layer of quantum dot (QD) light-emitting diodes (QLEDs), metal oxides are expected to be more stable compared with organic materials. However, the efficiency of metal oxide-based all-inorganic QLEDs is still far behind that of organic–inorganic hybrid ones. The main reason is the strong interaction between metal oxide and QDs leading to the emission quenching of QDs. Here, we demonstrated nickel oxide (NiOx)-based all-inorganic QLEDs with a maximum current efficiency of 20.4 cd A?1 and external quantum efficiency (EQE) of 5.5%, which is among the most efficient all-inorganic QLEDs. The high efficiency is mainly attributed to the aluminum oxide (Al2O3) deposited at the NiOx/QDs interface to suppress the strong quenching effect of NiOx on the QD emission, together with the molybdenum oxide (MoOx) that reduced the leakage current and facilitated hole injection, more than 300% enhancement was achieved compared with the pristine NiOx-based QLEDs. Our study confirmed the effect of decorating the NiOx/QDs interface on the performance enhancement of the all-inorganic QLEDs.
关键词： all-inorganic,high efficiency,NiOx,light-emitting devices,quantum dots
更新于2025-09-23 15:19:57
-
High-Efficiency Planar Reflectarray with Small-size for OAM Generation at Microwave Range
摘要： In this paper, a high-efficiency planar reflectarray with a small size 3.87λ0 × 3.87λ0 is designed, which can effectively convert arbitrary polarized waves to orbital angular momentum (OAM) waves with desired mode number and beam direction. The two concentric rings with a small size 0.38λ0 × 0.38λ0 compose the unit, which can cover the phase shifting range 360o by adjusting the ring radius. Though the developed reflectarray is much smaller than that of published ones, it can produce beams with the similar performance as large antennas. The advantages are as follows: high efficiency 22.6%, which is superior to published OAM reflectarrays, high gain 15.4 dBi, narrow divergence angle 9o, high purity, good stability, polarization insensitivity, planar structure, and easy fabrication. Using this reflective metasurface, we designed the following OAM beams: (1) OAM mode l = 1, 2, 3, 4 at (θ = 0o, φ = 0o). (2) l = 1 at (θ = 45o, φ = 180o). (3) l = 1 at (θ = 45o, φ = 270o). The above advantages are proved by the following analysis: (1) The magnitude and phase distributions in the near field. (2) The purity analysis. (3) The radiation pattern in the far field.
关键词： Orbital angular momentum (OAM),high efficiency,vortex beam,planar reflectarray antenna
更新于2025-09-19 17:15:36
-
High-efficiency near-infrared fluorescent organic light-emitting diodes with small efficiency roll-off based on AIE-active phenanthro[9,10- <i>d</i> ]imidazole derivatives
摘要： The simultaneous realization of high-efficiency and low-cost in fluorescent organic light-emitting diodes (OLEDs) is still a formidable challenge in deep-red (DR)/near-infrared (NIR) region because of the intrinsic limitation of the energy-gap law and fluorescence quenching effect. Herein, three novel donor-acceptor-donor′ (D-A-D′) fluorophores, PIBz-10-PTZ, PIBz-10P-PTZ and PIBz-3-PTZ, by utilizing phenanthro[9,10-d]imidazole and phenothiazine as the donor, benzothiadiazole as the acceptor are synthesized. Owing to the unilateral steric hindrance between adjacent hydrogen atoms along the horizontal axis, PIBz-3-PTZ possesses a completely planar conformation and fully conjugated structure. PIBz-3-PTZ exhibits a strong DR emission and aggregation induced emission (AIE) property with a high photoluminescence quantum yield of 35% in neat thin film. The nondoped OLEDs achieved a maximum external quantum efficiency (EQE) of 2.02% with an emission peak at 672 nm and the brightness of up to 3403 cd m-2. In addition, the device was able to maintain an EQE of 1.69% at high luminance of 100 cd m-2, with a low efficiency roll-off of 16%, suggesting the nondoped device can keep the brightness.
关键词： Near-Infrared,High-Efficiency,AIE-active,Phenanthro[9,10-d]imidazole Derivatives,Organic Light-Emitting Diodes,Small Efficiency Roll-Off,Fluorescent
更新于2025-09-19 17:13:59
-
Graphdiyne Derivative as Multifunctional Solid Additive in Binary Organic Solar Cells with 17.3% Efficiency and High Reproductivity
摘要： Morphology tuning of the blend film in organic solar cells (OSCs) is a key approach to improve device efficiencies. Among various strategies, solid additive is proposed as a simple and new way to enable morphology tuning. However, there exist few solid additives reported to meet such expectations. Herein, chlorine-functionalized graphdiyne (GCl) is successfully applied as a multifunctional solid additive to fine-tune the morphology and improve device efficiency as well as reproductivity for the first time. Compared with 15.6% efficiency for control devices, a record high efficiency of 17.3% with the certified one of 17.1% is obtained along with the simultaneous increase of short-circuit current (Jsc) and fill factor (FF), displaying the state-of-the-art binary organic solar cells at present. The redshift of the film absorption, enhanced crystallinity, prominent phase separation, improved mobility, and decreased charge recombination synergistically account for the increase of Jsc and FF after introducing GCl into the blend film. Moreover, the addition of GCl dramatically reduces batch-to-batch variations benefiting mass production owing to the nonvolatile property of GCl. All these results confirm the efficacy of GCl to enhance device performance, demonstrating a promising application of GCl as a multifunctional solid additive in the field of OSCs.
关键词： graphdiyne derivative,binary organic solar cells,high fill factor,high efficiency,solid additives
更新于2025-09-19 17:13:59
-
Europium and Acetate Co-doping Strategy for Developing Stable and Efficient CsPbI <sub/>2</sub> Br Perovskite Solar Cells
摘要： All-inorganic perovskite solar cells have developed rapidly in the last two years due to their excellent thermal and light stability. However, low efficiency and moisture instability limit their future commercial application. The mixed-halide inorganic CsPbI2Br perovskite with a suitable bandgap offers a good balance between phase stability and light harvesting. However, high defect density and low carrier lifetime in CsPbI2Br perovskites limit the open-circuit voltage (Voc < 1.2 V), short-circuit current density (Jsc < 15 mA cm?2), and fill factor (FF < 75%) of CsPbI2Br perovskite solar cells, resulting in an efficiency below 14%. For the first time, a CsPbI2Br perovskite is doped by Eu(Ac)3 to obtain a high-quality inorganic perovskite film with a low defect density and long carrier lifetime. A high efficiency of 15.25% (average efficiency of 14.88%), a respectable Voc of 1.25 V, a reasonable Jsc of 15.44 mA cm?2, and a high FF of 79.00% are realized for CsPbI2Br solar cells. Moreover, the CsPbI2Br solar cells with Eu(Ac)3 doping demonstrate excellent air stability and maintain more than 80% of their initial power conversion efficiency (PCE) values after aging in air (relative humidity: 35–40%) for 30 days.
关键词： CsPbI2Br perovskites,Eu(Ac)3,high stability,high efficiency,co-doping
更新于2025-09-19 17:13:59
-
Novel antisolvent-washing strategy for highly efficient carbon-based planar CsPbBr3 perovskite solar cells
摘要： All-inorganic CsPbBr3 is attracting tremendous attentions in photovoltaic field due to its superior stability. However, CsPbBr3 perovskite always suffers from a poor crystallinity and film morphology. Many efforts have been paid on the CsBr deposition process to improve the film quality, while few attentions are paid on the crystallization kinetics of the PbBr2 framework film. Here, we demonstrate a novel antisolvent-washing strategy for the PbBr2 film for the first time to fabricate high-quality CsPbBr3 film. This technique has a significant impact on the nucleation and growth of PbBr2 crystals. As-prepared CsPbBr3 films exhibit more homogeneous with higher crystallinity and coverage as well as larger grain sizes compared to those untreated ones. The best-performing antisolvent-treated perovskite solar cell achieves a scanned power conversion efficiency of 8.55%, which is an excellent efficiency for planar CsPbBr3 cells reported yet. This enhancement can be mainly attributed to the more effective charge transport and suppressed non-radiative recombination caused by the reduced defect densities. Moreover, our devices show superb stability when stored in air for 1000 h and upon persistent thermal attack at 80°C. Our work provides a new train of thought for controlling the growth dynamics and film morphology of CsPbBr3 films.
关键词： Antisolvent-washing,CsPbBr3,Planar heterojunction,High efficiency and stability,Carbon-based,Low costs
更新于2025-09-19 17:13:59
-
Surface modification induced by perovskite quantum dots for triple-cation perovskite solar cells
摘要： Organic-inorganic hybrid perovskite solar cells are regarded as the most promising new-generation photovoltaic technology, owing to their high power conversion efficiencies and low cost. However, surface imperfections of perovskite films impede improvement in device performances, since surface imperfections can introduce undesired energy losses under sunlight illumination. Here, we show that the incorporation of zero-dimensional perovskite quantum dots into three-dimensional perovskite films can heal surface imperfections in perovskite films. Introducing perovskite quantum dots also leads to a more uniform surface topography and potential, along with an improved crystal quality of the triple-cation perovskite films, benefiting charge carrier kinetics between the perovskite films and the charge extraction layers. Ultimately, we achieve a power conversion efficiency exceeding 21% in triple-cation perovskite solar cells.
关键词： quantum dots,surface modification,perovskite solar cells,high efficiency
更新于2025-09-19 17:13:59
-
[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Modeling the Incorporation of Microbeads into Concentrator Photovoltaic Systems
摘要： The Range Extensions (RExt) of the High Efficiency Video Coding (HEVC) standard have recently been approved by both ITU-T and ISO/IEC. This set of extensions targets video coding applications in areas including content acquisition, postproduction, contribution, distribution, archiving, medical imaging, still imaging, and screen content. In addition to the functionality of HEVC Version 1, RExt provide support for monochrome, 4:2:2, and 4:4:4 chroma sampling formats as well as increased sample bit depths beyond 10 bits per sample. This extended functionality includes new coding tools with a view to provide additional coding efficiency, greater flexibility, and throughput at high bit depths/rates. Improved lossless, near-lossless, and very high bit-rate coding is also a part of the RExt scope. This paper presents the technical aspects of HEVC RExt, including a discussion of RExt profiles, tools, applications, and provides experimental results for a performance comparison with previous relevant coding technology. When compared with the High 4:4:4 Predictive Profile of H.264/Advanced Video Coding (AVC), the corresponding HEVC 4:4:4 RExt profile provides up to ～25%, ～32%, and ～36% average bit-rate reduction at the same PSNR quality level for intra, random access, and low delay configurations, respectively.
关键词： extensions (RExt),range MPEG-H,compression,High Efficiency Video Coding (HEVC),H.265,video standards
更新于2025-09-19 17:13:59
-
Wavelength-stable 1.1 kW diode laser array cooled by liquid metal
摘要： While rate–distortion optimized quantization (RDOQ) technique provides nontrivial coding gain in High Efficiency Video Coding (HEVC), it also involves considerable computations, whereby the complexity of quantization is significantly increased. In this paper, two schemes (the RDOQ bypass decision and the simplified level adjustment) are investigated to reduce the complexity of the quantization process in HEVC with RDOQ. The RDOQ bypass decision method initially selects the transform blocks for which the RDOQ is expected to give less/or no coding gain and enables the conventional uniform scalar quantization to be applied to these transform blocks instead of the RDOQ. The simplified level adjustment method only estimates the difference in rate–distortion costs among the candidate quantization levels to enable the encoder to select an optimal quantization level at a much reduced computational cost. Furthermore, the proposed simplified level adjustment scheme is designed so that it can be implemented in lookup tables. Experimental results show that the proposed fast method achieves 14.3% quantization complexity reduction in all intra main conditions, 15.2% in the random access main condition, and 14.9% in the low delay main condition on average with virtually no coding loss compared with the conventional quantization process with the RDOQ.
关键词： rate–distortion optimized quantization (RDOQ),Fast quantization,High Efficiency Video Coding (HEVC)
更新于2025-09-19 17:13:59
-
Intensity noise self-suppression in a high-efficiency doubly resonant sum frequency mixing red laser
摘要： A doubly resonant sum frequency mixing laser at 636 nm with a maximum output power of 637 mW is demonstrated. The conversion efficiency of signal laser reaches 93% by optimizing the sum frequency mixing setup. Based on this high conversion efficiency, we realize the intensity noise self-suppression effect. Experimental results show that even the power fluctuation of pump power was modulated up to 7.8%, the power stability of 636 nm laser kept under 0.6%. The simulation results based on the exact solution of the coupled wave equations and cavity enhancement theory can explain the reason and property of the intensity noise self-suppression. Our results may find potential applications in the frequency conversion of the quantum squeezed states, imaging and cold atom physics.
关键词： high-efficiency,intensity noise self-suppression,red laser,doubly resonant sum frequency mixing
更新于2025-09-19 17:13:59