| 1. |
- Guo, Yiting, et al.
(författare)
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Effect of Side Groups on the Photovoltaic Performance Based on Porphyrin-Perylene Bisimide Electron Acceptors
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:38, s. 32454-32461
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we developed four porphyrin-based small molecular electron acceptors for non-fullerene organic solar cells, in which different side groups attached to the porphyrin core were selected in order to achieve optimized performance. The molecules contain porphyrin as the core, perylene bisimides as end groups, and the ethynyl unit as the linker. Four side groups, from 2,6-di(dodecyloxy)phenyl to (2-ethylhexyl)thiophen-2-yl, pentadecan-7-yl, and 3,5-di(dodecyloxy)phenyl unit, were applied into the electron acceptors. The new molecules exhibit broad absorption spectra from 300 to 900 nm and high molar extinction coefficients. The molecules as electron acceptors were applied into organic solar cells, showing increased power conversion efficiencies from 1.84 to 5.34%. We employed several techniques, including photoluminescence spectra, electroluminescence spectra, atomic force microscopy, and grazing-incidence wide-angle X-ray to probe the blends to find the effects of the side groups on the photovoltaic properties. We found that the electron acceptors with 2,6-di(dodecyloxy)phenyl units show high-lying frontier energy levels, good crystalline properties, and low nonradiative recombination loss, resulting in possible large phase separation and low energy loss, which is responsible for the low performance. Our results provide a detailed study about the side groups of non-fullerene materials, demonstrating that porphyrin can be used to design electron acceptors toward near-infrared absorption.
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| 2. |
- Li, Cheng, et al.
(författare)
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A diketopyrrolopyrrole-based macrocyclic conjugated molecule for organic electronics
- 2019
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 7:13, s. 3802-3810
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the first diketopyrrolopyrrole (DPP) based donor-acceptor macrocyclic conjugated molecule was developed and its application in organic electronics was systematically studied. Macrocyclic molecules, as a fragment of armchair carbon nanotubes, have emerged as functional materials in materials chemistry, but the materials are always limited to cycloparaphenylenes. Using the donor-acceptor design strategy that has been widely used in high performance conjugated polymers for macrocyclic molecules, it will significantly broaden their species with tunable optical and electrical properties. Herein, we synthesize a well-defined macrocyclic molecule containing four electron-deficient DPP units alternating with electron-rich thiophenes. The new molecule was found to show high solubility, near-infrared absorption spectra and 3D charge transport properties. The new macrocyclic molecule as an electron acceptor was applied to non-fullerene organic solar cells, exhibiting an initial efficiency of 0.49%, while the linear molecule with a similar backbone only showed a very low efficiency of 0.03%. Our results demonstrate that donor-acceptor macrocyclic conjugated materials have great potential application in organic electronics.
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| 3. |
- Chen, Xi, et al.
(författare)
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Ordered Au nanocrystals on a substrate formed by light-induced rapid annealing
- 2014
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:3, s. 1756-1762
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Tidskriftsartikel (refereegranskat)abstract
- Light-induced rapid annealing (LIRA) is a widely used method to modify the morphology and crystallinity of noble metal nanoparticles, and the nanoparticles generally evolve into nanospheres. It is rather challenging to form faceted Au nanocrystals on a substrate using LIRA. Here the formation of spatially ordered Au nanocrystals using a continuous wave infrared laser is reported, assisted by a metamaterial perfect absorber. Faceted Au nanocrystals in truncated-octahedral or multi-twinned geometries can be obtained. The evolution of morphology and crystallinity of the Au nanoparticles during laser annealing is also revealed, where the crystal grain growth and the surface melting are shown to play key roles in nanocrystal formation. The evolution of morphology also gives the freedom of tuning the absorption spectrum of the metamaterial absorber. These findings provide a novel way for tailoring the morphology and crystallinity of metallic nanoparticles and may pave the way to fabricate refined nano-devices in many potential applications for optics, electronics, catalysis, surface-chemistry and biology.
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| 4. |
- Chen, Yiting, et al.
(författare)
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GraspAda: Deep Grasp Adaptation through Domain Transfer
- 2023
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Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - 1050-4729. - 9798350323658 ; 2023-May
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Konferensbidrag (refereegranskat)abstract
- Learning-based methods for robotic grasping have been shown to yield high performance. However, they rely on expensive-to-acquire and well-labeled datasets. In addition, how to generalize the learned grasping ability across different scenarios is still unsolved. In this paper, we present a novel grasp adaptation strategy to transfer the learned grasping ability to new domains based on visual data using a new grasp feature representation. We present a conditional generative model for visual data transformation. By leveraging the deep feature representational capacity from the well-trained grasp synthesis model, our approach utilizes feature-level contrastive representation learning and adopts adversarial learning on output space. This way we bridge the domain gap between the new domain and the training domain while keeping consistency during the adaptation process. Based on transformed input grasp data via the generator, our trained model can generalize to new domains without any fine-tuning. The proposed method is evaluated on benchmark datasets and based on real robot experiments. The results show that our approach leads to high performance in new scenarios.
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| 5. |
- Currie, Thayne, et al.
(författare)
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SCExAO/CHARIS Direct Imaging Discovery of a 20 au Separation, Low-mass Ratio Brown Dwarf Companion to an Accelerating Sun-like Star
- 2020
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 904:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the direct imaging discovery of a substellar companion to the nearby Sun-like star, HD 33632 Aa, at a projected separation of similar to 20 au, obtained with SCExAO/CHARIS integral field spectroscopy complemented by Keck/NIRC2 thermal infrared imaging. The companion, HD 33632 Ab, induces a 10.5 sigma astrometric acceleration on the star as detected with the Gaia and Hipparcos satellites. SCExAO/CHARIS JHK (1.1-2.4 mu m) spectra and Keck/NIRC2 L-p (3.78 mu m) photometry are best matched by a field L/T transition object: an older, higher-gravity, and less dusty counterpart to HR 8799 cde. Combining our astrometry with Gaia/Hipparcos data and archival Lick Observatory radial velocities, we measure a dynamical mass of 46.4 8 M-J and an eccentricity of e < 0.46 at 95% confidence. HD 33632 Ab's mass and mass ratio (4.0% 0.7%) are comparable to the low-mass brown dwarf GJ 758 B and intermediate between the more massive brown dwarf HD 19467 B and the (near-)planet-mass companions to HR 2562 and GJ 504. Using Gaia to select for direct imaging observations with the newest extreme adaptive optics systems can reveal substellar or even planet-mass companions on solar system-like scales at an increased frequency compared to blind surveys.
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| 6. |
- Gong, Hanmo, et al.
(författare)
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Gold nanoparticle transfer through photothermal effects in a metamaterial absorber by nanosecond laser
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 6080-
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Tidskriftsartikel (refereegranskat)abstract
- A non-complicated, controllable method of metallic nanoparticle fabrication at low operating light power is proposed. The method is based on laser-induced forward transfer, using a metamaterial absorber as the donor to significantly enhance the photothermal effect and reduce the operating light fluence to 35 mJ/cm(2), which is much lower than that in previous works. A large number of metallic nanoparticles can be transferred by one shot of focused nanosecond laser pulses. Transferred nanoparticles exhibit good size uniformity and the sizes are controllable. The optical properties of transferred particles are characterized by dark-field spectroscopy and the experimental results agree with the simulation results.
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| 7. |
- Li, Qiang, et al.
(författare)
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Efficient directional coupler based on plasmonic waveguide for photonic integrated circuits
- 2010
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Ingår i: International Conference on Optical Communications and Networks 2010. - : IET. - 9781849193146 ; , s. 366-368
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Konferensbidrag (refereegranskat)abstract
- Two asymmetric directional couplers, including the dielectric-hybrid plasmonic coupler and the dielectric-metalinsulator-metal plasmonic coupler, are investigated. The proposed hybrid coupler features short coupling length, high coupling efficiency and can be integrated into the siliconbased platform. The applications of these hybrid couplers include the signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits and efficient excitation of plasmonic modes with conventional dielectric modes. Besides, a symmetric directional coupler based on silver nanowires is also demonstrated.
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| 8. |
- Li, Qiang, et al.
(författare)
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Experimental Demonstration of Plasmon Propagation, Coupling, and Splitting in Silver Nanowire at 1550-nm Wavelength
- 2011
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X .- 1558-4542. ; 17:4, s. 1107-1111
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate silver-nanowire-based plasmonic devices including the nanowaveguide, the nanocoupler, and the nanosplitter at optical communication wavelength of 1550 nm. The plasmon propagation loss in a 300-nm diameter silver nanowire is measured to be 0.3 dB/mu m and the effective propagation length is 14.5 mu m. This loss is comparatively lower than that at 980 nm. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nanocouplers, and nanosplitters, are realized. For the nanocoupler, the experimental results show that the plasmonic modes can be efficiently coupled between two closely positioned nanowires. While for the nanosplitter, the plasmonic mode is split with a power ratio of 2.6:1. These demonstrations experimentally prove the feasibility of extending the operating wavelength of silver-nanowire-based plasmonic devices to current optical communication wavelength with a lower loss, which are thus important steps for potentially utilizing low-loss nanowire-based plasmonic components for photonic integrated circuits.
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| 9. |
- Li, Qiang, et al.
(författare)
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Experimental demonstration of plasmon propagation, coupling, and splitting in silver nanowire at 1550-nm wavelength
- 2011
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : IEEE. - 1077-260X .- 1558-4542. ; 17:4, s. 1107-1111
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate silver-nanowire-based plasmonic devices including the nanowaveguide, the nanocoupler, and the nanosplitter at optical communication wavelength of 1550 nm. The plasmon propagation loss in a 300-nm diameter silver nanowire is measured to be 0.3 dB/μm and the effective propagation length is 14.5 μm. This loss is comparatively lower than that at 980 nm. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nanocouplers, and nanosplitters, are realized. For the nanocoupler, the experimental results show that the plasmonic modes can be efficiently coupled between two closely positioned nanowires. While for the nanosplitter, the plasmonic mode is split with a power ratio of 2.6:1. These demonstrations experimentally prove the feasibility of extending the operating wavelength of silver-nanowire-based plasmonic devices to current optical communication wavelength with a lower loss, which are thus important steps for potentially utilizing low-loss nanowire-based plasmonic components for photonic integrated circuits.
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| 10. |
- Li, Qiang, et al.
(författare)
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Silver nanowire based plasmon propagation, coupling and splitting at 1.55 mu m wavelength
- 2011
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 7986
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate silver nanowire based plasmonic devices at optical communication wavelength 1.55 mu m. The plasmon propagation loss in a 300 nm diameter silver nanowire is measured to be 0.3 dB/mu m. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nano-couplers and nano-splitters, are realized.
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| 11. |
- Li, Qiang, et al.
(författare)
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Silver nanowire based plasmon propagation, coupling and splitting at 1.55 μm wavelength
- 2010
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Ingår i: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010. - 9781424471119 ; , s. 497-498
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate silver nanowire based plasmonic devices at optical communication wavelength 1.55 μm. The plasmon propagation loss in a 300 nm diameter silver nanowire is measured to be 0.3 dB/μm. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nano-couplers and nano-splitters, are realized.
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| 12. |
- Li, Qiang, et al.
(författare)
-
Silver nanowire based plasmon propagation, coupling and splitting at 1.55 μm wavelength
- 2010
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Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : Optical Society of America (OSA). - 9780819485540
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate silver nanowire based plasmonic devices at optical communication wavelength 1.55 μm. The plasmon propagation loss in a 300 nm diameter silver nanowire is measured to be 0.3 dB/μm. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nano-couplers and nano-splitters, are realized.
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| 13. |
- Li, Yiting, et al.
(författare)
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Central limit theorem for mesoscopic eigenvalue statistics of deformed Wigner matrices and sample covariance matrices
- 2021
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Ingår i: Annales de l'I.H.P. Probabilites et statistiques. - : Project Euclid. - 0246-0203 .- 1778-7017. ; 57:1, s. 506-546
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Tidskriftsartikel (refereegranskat)abstract
- We consider N by N deformed Wigner random matrices of the form X-N = H-N + A(N), where H-N is a real symmetric or complex Hermitian Wigner matrix and A(N) is a deterministic real bounded diagonal matrix. We prove a universal Central Limit Theorem for the linear eigenvalue statistics of X-N for all mesoscopic scales both in the spectral bulk and at regular edges where the global eigenvalue density vanishes as a square root. The method relies on studying the characteristic function of the linear statistics (Landon and Sosoe (2018)) by using the cumulant expansion method, along with local laws for the Green function of X-N (Ann. Probab. 48 (2020) 963-1001; Probab. Theory Related Fields 169 (2017) 257-352; J. Math. Phys. 54 (2013) 103504) and analytic subordination properties of the free additive convolution (Dallaporta and Fevrier (2019); Random Matrices Theory Appl. 9 (2020) 2050011). We also prove the analogous results for high-dimensional sample covariance matrices.
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| 14. |
- Li, Yiting, et al.
(författare)
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On fluctuations of global and mesoscopic linear statistics of generalized Wigner matrices
- 2021
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Ingår i: Bernoulli. - : Bernoulli Society for Mathematical Statistics and Probability. - 1350-7265 .- 1573-9759. ; 27:2, s. 1057-1076
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Tidskriftsartikel (refereegranskat)abstract
- We consider an N by N real or complex generalized Wigner matrix H-N, whose entries are independent centered random variables with uniformly bounded moments. We assume that the variance profile, s(ij) := E vertical bar H-ij vertical bar(2), satisfies Sigma(N)(i=1) s(ij) = 1, for all 1 <= j <= N and c(-1) <= Ns(ij) <= c for all 1 <= i, j <= N with some constant c >= 1. We establish Gaussian fluctuations for the linear eigenvalue statistics of HN on global scales, as well as on all mesoscopic scales up to the spectral edges, with the expectation and variance formulated in terms of the variance profile. We subsequently obtain the universal mesoscopic central limit theorems for the linear eigenvalue statistics inside the bulk and at the edges, respectively.
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| 15. |
- Qiu, Min, et al.
(författare)
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Nanostructured plasmonic devices and their applications
- 2013
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Ingår i: 2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013. - : IEEE. - 9781479904655 ; , s. 79-80
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Konferensbidrag (refereegranskat)abstract
- In this talk, we will review our recent works on nanostructured plasmonic devices, and their applications in high performance light absorption, photothermal effects, and partly in photonic integrations.
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| 16. |
- Qiu, Min, et al.
(författare)
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Plasmonic enhanced photothermal effects and its applications
- 2014
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Konferensbidrag (refereegranskat)abstract
- We review here our recent studies on plasmonic enhanced photothermal effects in metallic nanostructure, and the applications of such effects. When light is shined on a prefect metamaterial absorber patterned with e-beam lithography, the gold nanoparticles (NPs) forming the absorber can be either transformed to nano-spherical-domes, or to truncated-octahedral shaped or multi-twined nanocrystals with large crystal grain sizes and flat boundary facets. The evolution of morphology and crystallinity of the gold NPs can be also observed. Evidences clearly show that the surface melting and the coalescence mechanism play a key role on nanocrystals formation. These melted gold nanospheres can even be transferred to another substrate, on which the transferred NPs exhibit excellent size uniformity. The strong photothermal effects can also be utilized to tune silicon photonics waveguides and resonators. It is shown that all-optical photothermal switching of Mach-Zehnder interferometers (MZI), silicon disk resonators, and silicon ring resonators is possible with the help of plasmonic nanoheaters. The switching response time and power consumption are all at reasonably low level.
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| 17. |
- Wang, Wei, et al.
(författare)
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Grating-assisted enhanced optical transmission through a seamless gold film
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:5, s. 5416-5421
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we experimentally demonstrate enhanced optical transmission through a seamless gold film based on the grating-insulator-metal (GIM) architecture. The transmittance of this GIM structure reaches 40% at 930 nm, showing 3.7 dB and 9.1 dB increase compared with a bare gold film and a continuous metal-insulator-metal stack, respectively. The enhanced transmission is polarization-sensitive and robust for oblique incidence. With tunable transmission peaks, such a device exhibits great potential for applications in optical filtering, polarization detecting and further integration in optoelectronics system.
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| 18. |
- Zhao, Ding, et al.
(författare)
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Ultra-narrow-band light dissipation by a stack of lamellar silver and alumina
- 2014
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 104:22
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Tidskriftsartikel (refereegranskat)abstract
- An ultra-narrow band absorber consisting of continuous silver and alumina films is investigated. Owing to Fabry–Pérot resonance and silver's inherent loss, an ultra-narrow spectral range of light can be entirely trapped in the structure. By varying thicknesses of metallic and dielectric films, absorption peak shifts in visible and near-infrared regions. When two such metal-insulator-metal stacks are cascaded, experimental results show that an ultra-narrow absorption bandwidth of 7 nm is achieved, though theoretical results give that of 2 nm. Features of high-efficiency and ultra-narrow band absorption have huge potential in optical filtering, thermal emitter design, etc.
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