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- 实验方案
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Single-layer planar penta-X2N4 (X= Ni, Pd and Pt) as direct-bandgap semiconductors from first principle calculations
摘要： Using first principle calculations we have investigated the structure stabilities, electronic and optical properties of single layer planar penta-X2N4 (X=Ni, Pd and Pt). According to the calculated phonon dispersion relation and elastic constants, as well as ab initio molecular dynamics simulation results, monolayers of planar penta-X2N4 are dynamically, mechanically, and thermally stable. In addition, these monolayers are direct-gap semiconductors with sizeable bandgaps ranging from 0.92 eV to 1.11 eV, which can be further tuned by external strains. Besides, the bonding characteristics and the optical properties in these monolayers are investigated based on HSE06 calculations, where strong in-plane optical absorption with wide spectral range has been revealed. Our results indicate that planar penta-X2N4 monolayers possess excellent electrical and optical properties, and may find potential applications in solar cells and nanoelectronics.
关键词： Electronic properties,First principle calculations,Optical properties,Direct-bandgap semiconductors,Planar penta-X2N4
更新于2025-09-23 15:21:01
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HIGHLY SELECTIVE LOSSY DUAL-BAND BANDSTOP FILTER SYNTHESIS AND DESIGN BASED ON PREDISTORTION HYBRID DUAL-BAND ELLIPTIC REFECTION FUNCTION
摘要： This paper demonstrates a new class of highly selective bandstop ?lter based on cascading two identical lossy hybrid dual-band bandstop ?lters of low resonator Q factor. Each ?lter is synthesized based on multi-stage predistortion re?ection mode technique. To demonstrate the approach, 4th order hybrid dual-band elliptic ?lter network which is a product of elliptic lowpass and highpass network functions has been predistorted and synthesized with low calculated Q factor. The lossy dual-band bandstop ?lters are fabricated and realized on microstrip planar structure. Both theoretical and experimental results clearly show good agreements with two stopband rejections up to 35 dB for one stage and 50 dB for two stages with passband loss of more than 10 dB.
关键词： microstrip planar structure,highly selective bandstop ?lter,predistortion re?ection mode technique,lossy hybrid dual-band bandstop ?lters
更新于2025-09-23 15:21:01
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5-Channel Polymer/Silica Hybrid Arrayed Waveguide Grating
摘要： A 5-channel polymer/silica hybrid arrayed waveguide grating (AWG), fabricated through a simple and low-cost microfabrication process is proposed, which covers the entire O-band (1260–1360 nm) of the optical communication wavelength system. According to the simulation results, the insertion loss is lower than 4.7 dB and the crosstalk within 3-dB bandwidth is lower than ~?28 dB. The actual fiber–fiber insertion loss is lower than 14.0 dB, and the crosstalk of the 5 channels is less than ?13.0 dB. The demonstrated AWG is ideally suitable for optical communications, but also has potential in the multi-channel sensors.
关键词： integrated optics,polymer optical waveguides,planar lightwave circuit,optical communication systems
更新于2025-09-23 15:19:57
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The influence of fullerene on hysteresis mechanism in planar perovskite solar cells
摘要： Despite the rapid development of perovskite devices, the current density-voltage hysteresis still needs to be conquered. Here, the introduction of PCBM into the active layer of planar perovskite solar cells is carried out and hysteresis-free devices are produced. A photoluminescence blue-shift in PCBM-doped perovskite ?lms is observed. The e?ect of non-radiative recombination is obviously suppressed, and the photoluminescence lifetime is signi?cantly prolonged by 3-fold after PCBM introduction. The roles of PCBM in trap states and hysteresis mechanism are also discussed. This research could provide experimental and theoretical supports for suppressing and eliminating the hysteresis phenomena in perovskite solar cells.
关键词： Hysteresis,Trap states,Planar perovskite solar cells,PCBM
更新于2025-09-23 15:19:57
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Air-stable hybrid perovskite solar cell by sequential vapor deposition in a single reactor
摘要： Here we demonstrate a facile two-step low-pressure vapor deposition of methyl-ammonium lead iodide (MAPbI3) perovskite films in a single reactor. Continuous, poly-crystalline lead iodide (PbI2) films were deposited in the first step and successfully converted to high quality perovskite films in the second step during exposure of PbI2 films to methyl-ammonium iodide (MAI) vapor. A complete conversion was realized after 90 minutes of exposure with an average grain size of 3.70 ± 1.80 μm. The perovskite conversion starts at the PbI2 surface through the intercalation reaction of PbI2 and MAI vapor molecules and progresses towards the PbI2/substrate interface. The coverage and quality of the perovskite thin film is controlled by that of the pre-deposited PbI2 film. The absorbance measurements confirmed air stability of the fully converted perovskite for 21 days, ascribed to its superior morphology and grain size. Finally, a planar single-junction perovskite solar cell with no additives or additional interfacial engineering was fabricated and tested under open-air conditions, yielding a best power conversion efficiency of 11.7%. The solar cell maintains 85% of its performance up to 13 days in open-air with relative humidity up to 80%.
关键词： planar device,Two-step vapor deposition,large grains,intercalation,air-stable
更新于2025-09-23 15:19:57
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Efficient Organic Solar Cells Based on Non-Fullerene Acceptors with Two Planar Thiophene Fused Perylene Diimide Units
摘要： We designed and synthesized two non-fullerene acceptors (CDT-TFP and C8X-TFP), which comprise a central 4H-cyclopenta[2,1-b:3,4-b’]dithiophene (CDT) as the bridge and two thiophene-fused perylene diimide (TFP) units. The bulky side chains, such as the 4-hexylphenyl side chains, on the CDT bridge can effectively prevent the acceptor molecules from forming large aggregates and the π-π stacking of the terminal planar TFP units can form effective electron transport pathways when blending with the donor polymers. These non-fullerene acceptors are used to fabricate organic solar cells (OSCs) by blending with regioregular middle bandgap polymer reg-PThE. The as-cast devices based on reg-PThE:CDT-TFP show the best PCE of 8.36% with a Voc of 1.10 V, Jsc of 12.43 mA cm-2 and FF of 61.4%; whereas, the analogue PDI dimers (CDT-PDI) that comprising two PDI units bridged with a CDT unit, show only a 2.59% PCE with a Voc of 0.92 V, Jsc of 6.82 mA cm-2 and FF of 41.5%. Our results have demonstrated that non-fullerene acceptors comprising planar PDI units can achieve excellent photovoltaic performance and provide meaningful guidelines for the design of PDI based non-fullerene electron acceptors for efficient OSCs.
关键词： regioregular donor polymer,perylene diimide,organic solar cells,non-fullerene electron acceptors,planar
更新于2025-09-23 15:19:57
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High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs <sub/>1a??x</sub> Sb <sub/>x</sub> superlattice photodetector by MOCVD
摘要： We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1?xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10?8 A/cm2 under an applied bias of ?20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10?6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W.
关键词： specific detectivity,metal-organic chemical vapor deposition,type-II InAs/InAs1?xSbx superlattices,quantum efficiency,Zn-diffused planar mid-wavelength infrared photodetector
更新于2025-09-23 15:19:57
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Laser direct writing lithography for rapid fabrication on non-planar surfaces
摘要： A modified laser direct writing lithography system with dynamic focusing is presented. This improved system can realize rapid fabrication on non-planar surfaces with large curvature and it offers new possibilities for fabricating micro-patterns on curved surfaces in an easy and fast way. A dynamic focusing lens group which is driven by a linear voice coil motor is introduced and it can rapidly control the laser spot to focus on the curved surface when processing in real-time. The focus range is almost 10 mm and it can be larger when working with the z-stage. The mathematic expression of dynamic focusing is deduced and the corresponding experiment results agree with the numerical analysis, which shows the practicability of the system. The effects of slopes with different tilted angles on exposure linewidth are studied. Finally, a concentric-circle grating is fabricated on a convex substrate with a diameter of 30 mm and a radius of curvature of 19.918 mm. The grating has homogeneous linewidth of 10 μm and line space of 20 μm, and the total processing time is within 40s. This technique can greatly improve the efficiency and has great potentials, such as rapid fabrication of diffractive optical elements (DOEs) or microelectromechanical systems (MEMS) on arbitrary 3D curved surfaces.
关键词： non-planar surfaces,dynamic focusing,micro-patterns,rapid fabrication,laser direct writing lithography
更新于2025-09-23 15:19:57
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Electromagnetic Physical Numerical Modeling of a GaN Distributed Transferred Electron Devicea??Based Planar Waveguide THz Oscillator
摘要： The radio frequency (RF) operation of a planar waveguide THz oscillator based on the distributed transferred electron device (DTED) is theoretically investigated by means of 2-D time-domain numerical physical modeling based on the self-consistent solution of the Maxwell and free electron energy-momentum macroscopic transport equations.
关键词： circuit design analysis,distributed transferred electron device (DTED),2-D time-domain electromagnetic physical numerical modeling,planar waveguide THz oscillator
更新于2025-09-23 15:19:57
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Electrodeposition of CuI Thin Film for Perovskite Solar Cells
摘要： The CuI thin film has been successfully prepared by using cathodic electrodeposition method. The synthesized film was characterized using advanced techniques such as XRD, SEM-EDX and UV measurements. The films are crystallized in face centered cubic structure. The crystallinity is increasing for the applied potential of -0.3 V and the crystallinity deteriorates on increasing the potential above - 0.3 V. It was also observed that the applied voltage plays an important role. Homogeneously distributed triangular faceted morphology was observed from SEM. This is consistent with the result of XRD that electrodeposited CuI thin films grow preferential orientation along the (111) crystal plane.
关键词： CuI,Stability,Inverted planar PSC,Electrodeposition,HTM
更新于2025-09-23 15:19:57