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Label Stacking Scenarios in Hybrid Wavelength and Code-Switched GMPLS Networks
摘要： Multi-protocol label switching (MPLS) is a promising solution to implement high-speed internet protocol (IP) networks by reducing the layer number. To meet the increasing demand for data traffic, optical packet switching (OPS) is integrated under IP to provide high bandwidth to end users. Generalized MPLS (GMPLS) is perfectly compatible with the routing algorithm in IP/MPLS as it supports packet-switching functions. In this paper, we investigate the label stacking scenarios in GMPLS networks. In GMPLS, label stacking is done to reduce the node complexity by appending multiple labels to a single packet. Wavelength-division multiplexing (WDM) and optical code-division multiplexing (OCDM) signals have been widely used as identifying labels. As the labels can be permutated among the wavelengths or code dimensions, the structure of a label stack can be varied. However, studies on the relationship between label stacking scenarios and network performance are limited. To investigate this issue, we propose three label stacking models: sequential code distribution; sequential wavelength distribution, and random label distribution. The simulation results show that the sequential wavelength assignment, wherein the labels are uniformly distributed among the wavelengths, exhibits the best system performance in terms of the label-error rate (LER).
关键词： label stacking,generalized multi-protocol label switching (GMPLS),wavelength-division multiplexing (WDM),optical code-division multiplexing (OCDM)
更新于2025-09-23 15:21:21
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Preferred orientation of 2,7-dioctyl[1]benzothieno[3,2- <i>b</i> ][1]benzothiophene molecules on inorganic single-crystal substrates with various orientations
摘要： The organic molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) was deposited on quartz glass, e11 (cid:2)20T A-, (0001) C-, and e1 (cid:2)102T R-single-crystal Al2O3 (sapphire), and (100)-, and (111)-single-crystal MgO substrates by vacuum thermal evaporation, and structural characterizations were carried out by X-ray di?raction analysis and atomic force microscopy (AFM) observation. The (001) out-of-plane orientation with a similar in-plane orientation was obtained irrespective of the substrate material and orientation, and its formation was governed by π–π-stacking-induced molecular ordering. The degree of orientation was re?ected by the grain structure related to the substrate material. The growth model of the oriented C8-BTBT layer was speculated on the basis of experimental results.
关键词： π–π-stacking,vacuum thermal evaporation,X-ray diffraction,C8-BTBT,atomic force microscopy
更新于2025-09-23 15:21:21
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D-??-D molecular semiconductors for perovskite solar cells: the superior role of helical versus planar ??-linker
摘要： Controlling the mode of molecular packing and the size of molecular aggregate are of fundamental importance for high-performance charge transporting materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as kernal blocks in the exploration of unconventional organic semiconductors, in this work thia[5]helicene (T5H) is duplicately aminated with electron-donating dimethoxydiphenylamine to afford T5H-OMeDPA, which is systematically compared with its perylothiophene (PET) congener (PET-OMeDPA). On the basis of quantum theory of atoms in molecules and energy decomposition analysis of single-crystals, it is suprisingly found that while π-π stacking of planar PET is stronger than that of helical T5H, this desirable effect for charge transport of organic semiconductors is completely lost for donor-π-donor (D-π-D) typed PET-OMeDPA, but is retained for T5H-OMeDPA to a large extent. Consequently, T5H-OMeDPA single-crystal presents an about 5 times higher theoretical hole-mobility than PET-OMeDPA. More critically, the solution-processed racemic glassy film of T5H-OMeDPA displays a 3 times higher hole-mobility in comparison with the PET-OMeDPA counterpart, due to a larger domain of molecular aggregate. With respect to PET-OMeDPA, there is a weaker electronic coupling of helical T5H-OMeDPA with perovskite, leading to a reduced interfacial charge recombination. Due to reduced transport resistance and enhanced recombination resistance, perovskite solar cells with T5H-OMeDPA exhibit a power conversion efficiency of 21.1%, higher than that of 19.8% with PET-OMeDPA and that of 20.6% with spiro-OMeTAD control.
关键词： charge transport,perovskite solar cells,helicene,molecular semiconductors,π-π stacking
更新于2025-09-23 15:21:01
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Design Optimization of Photovoltaic Cell Stacking in a Triple-Well CMOS Process
摘要： Various self-powered devices employ energy-harvesting technology to capture and store an ambient energy. The photovoltaic (PV) cell is one of the most preferred approaches due to its potential for on-chip integration. Although serial connection of multiple PV cells is commonly required to obtain a sufficiently high voltage for circuit operation, a voltage boosting with serially stacked PV cells is limited in a standard bulk CMOS process because all the PV cells are intrinsically connected to the common substrate. It is possible to increase the output voltage by stacking multiple PV cells with a large area ratio between stages. However, nonoptimal design results in a poor conversion efficiency or a limited open-circuit voltage, making it unsuitable for practical applications. This article proposes a stacking structure and its optimal design method for PV cell stacking in a triple-well CMOS process. The proposed approach utilizes an additional current-sourcing photodiode and an optical filter, which allow high voltage generation without a significant efficiency degradation. The test chip with four-stage stacked PV cells was fabricated using a 0.25-μm standard triple-well CMOS process. The experimental results demonstrate an output voltage of 1.6 V and an electrical power of 263 nW/mm2 under an incident illumination with an intensity of 96 μW/mm2, achieving a responsivity of 1.91 mA/W and a conversion efficiency of 0.27%.
关键词： on-chip solar cell,photovoltaic (PV) cell stacking,Energy harvesting,voltage boosting
更新于2025-09-23 15:21:01
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[NH3(CH2)6NH3]PbI4 as Dion-Jacobson Phase Bifunctional Capping Layer for 2D/3D Perovskite Solar Cells with High Efficiency and Excellent UV Stability
摘要： Currently, three-dimensional (3D) organic–inorganic hybrid metallic halide perovskites are emerging as optoelectronic materials, but they demonstrate poor stability against heat and moisture and are vulnerable to oxidation and photodegradation upon exposure to ultraviolet (UV) light. Herein, for the first time, 1,6-diaminohexane ammonium (HDAD+) is demonstrated to be a unique cation spacer to prepare a two-dimensional Dion-Jacobson phase (DJP) perovskite that is ultimately used to construct a 2D/3D stacking structure. Compared to 3D perovskites and Ruddlesden-Popper phase (RPP)-2D perovskites, the DJP-2D perovskite demonstrates superior UV stability and can efficiently protect the 3D layer underneath from being damaged by the UV light. Moreover, the DJP-2D perovskite can also act as an interfacial layer to passivate the defects located on top of the 3D perovskite, resulting in a notably increased photoluminescence lifetime and suppression of interfacial charge recombination. As a result, the power conversion efficiency (PCE) is enhanced from 19.22% (3D) to 20.31% (2D/3D) and is accompanied by improved moisture and thermal stabilities.
关键词： Dion-Jacobson phase,2D/3D stacking structure,UV stability,optoelectronic materials,perovskite solar cells
更新于2025-09-23 15:21:01
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Defect generation by nitrogen during pulsed sputter deposition of GaN
摘要： Pulsed sputter deposition has been demonstrated to be a viable process for the growth of high quality GaN and InGaN/GaN LEDs. It enables the fabrication of nitride LEDs with a red emission wavelength at large areas. In this study, we explore details on the epitaxial sputter deposition of GaN with a particular emphasis on ion damage. By changing the argon to nitrogen ratio, we adjust the growth mode from island to layer growth. TEM revealed speckles in the epitaxial GaN, which could be identi?ed as isolated basal stacking faults, acting as non-radiative recombination centers. Using Monte Carlo methods, we modeled the energies of backscattered and sputtered atoms in order to get information on the ion damage mechanisms. Considering the collisions on the way from the target to the substrate, we found energetic nitrogen to induce the speckles. A shielding mechanism based on metallic gallium has been identi?ed, leading to the strongly increased luminescence quality in comparison to the non-shielded material.
关键词： GaN,pulsed sputter deposition,stacking faults,luminescence,ion damage
更新于2025-09-23 15:21:01
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Tricolor luminescence switching by thermal and mechanical stimuli in the crystal polymorphs of pyridyl substituted fluorene
摘要： Stimuli-responsive organic luminescence switching materials have attracted much attention for a decade. Most of the reported examples display a reversible two-color luminescence switching, multicolor switched materials remain extremely lacking due to the un-designability of this kind of smart materials. Herein, we reported a simple organic molecule, 4,4'-(9,9-dimethyl-9H-fluorene-2,7-diyl)dipyridine (MFDP), which exhibited three different crystal polymorphs (V-MFDP, B-MFDP and G-MFDP) with different luminescent colors. Furthermore, the three crystal polymorphs showed a reversible tricolor fluorescent switching from violet to blue and to green upon physical stimuli. The single-crystal structures of the three polymorphs were obtained, and the results indicate that, the stimuli response properties of the three polymorphs come from the different stacking modes induced by intermolecular interactions. The competition between weak π?π stacking and weak hydrogen bonding is the main reason for the the phase transformations among the three crystal polymorphs.
关键词： Fluorene,π–π Stacking,Crystal Structure,Luminescence Switching,Stimuli-response
更新于2025-09-23 15:21:01
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Aryl substitution of pentacenes
摘要： A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices.
关键词： organic semiconductor,pentacene,π-stacking,solid-state structure,carbon-nanomaterials,polycyclic aromatic hydrocarbon
更新于2025-09-23 15:21:01
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In situ atomic level studies of thermally controlled interlayer stacking shifts in 2D transition metal dichalcogenide bilayers
摘要： We show interlayer stacking shifts occur in transition metal dichalcogenides (TMD) bilayers due to the strain introduced during sample heating, and attributed to rippling of one layer relative to the other. The atomic structure of the interlayer stacking is studied using annular dark field scanning transmission electron microscopy with an in situ heating holder. Before heating, bilayers show uniform interlayer stacking of AA9 and AB. When heated, contrast change is seen and associated with interlayer stacking changes at the atomic scale due to ripples. When cooled down to room temperature, these contrast features disappear, confirming it is a reversible process that is not related to defects or vacancies. Because the bottom layer is attached to the in situ heating chip made from Si3N4 and the top layer is in contact with the underlying TMD layer with weak van der Waals interaction, the two layers experience different forces during thermal expansion.
关键词： transition metal dichalcogenides,thermal expansion,scanning transmission electron microscopy,interlayer stacking,2D materials
更新于2025-09-23 15:19:57
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Significantly Enhanced Molecular Stacking in Ternary Bulk Heterojunctions Enabled by an Appropriate Side Group on Donor Polymer
摘要： Ternary strategy is a promising approach to broaden the photoresponse of polymer solar cells (PSCs) by adopting combinatory photoactive blends. However, it could lead to a more complicated situation in manipulating the bulk morphology. Achieving an ideal morphology that enhances the charge transport and light absorption simultaneously is an essential avenue to promote the device performance. Herein, two polymers with different lengths of side groups (P1 is based on phenyl side group and P2 is based on biphenyl side group) are adopted in the dual-acceptor ternary systems to evaluate the relationship between conjugated side group and crystalline behavior in the ternary system. The P1 ternary system delivers a greatly improved power conversion efficiency (PCE) of 13.06%, which could be attributed to the intense and broad photoresponse and improved charge transport originating from the improved crystallinity. Inversely, the P2 ternary device only exhibits a poor PCE of 8.97%, where the decreased device performance could mainly be ascribed to the disturbed molecular stacking of the components originating from the overlong conjugated side group. The results demonstrate a conjugated side group could greatly determine the device performance by tuning the crystallinity of components in ternary systems.
关键词： ternary systems,ternary bulk heterojunctions,complementary absorption,polymer solar cells,molecular stacking,side chain effect
更新于2025-09-23 15:19:57