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Flexible four-junction inverted metamorphic AlGaInP/AlGaAs/ In0.17Ga0.83As/In0.47Ga0.53As solar cell
摘要： A flexible four-junction (4 J) AlGaInP/AlGaAs/In0.17Ga0.83As/In0.47Ga0.53As solar cell with the band gap energy of 1.92/1.53/1.18/0.82eV was fabricated. Taking advantages of aluminum (Al)-contained material as well as metamorphic growth, the design of multiple junction solar cells became much easier and more flexible. In order to accommodate lattice mismatch between two InGaAs sub cells, compositionally step-graded AlGaInAs buffer layers were applied to release the mismatch strain during the inverted metamorphic (IMM) 4 J solar cells growth. A flexible 4 J solar cell on a 50 μm thick polyimide (PI) film was successfully fabricated by using temporary bonding and epitaxial layer lift-off via selective wet chemical etching. A conversion efficiency of 25.76% (AM1.5G) with an open circuit voltage of 3.46V, a short-circuit current density of 9.07 mA/cm2 and a fill factor of 82.14% was obtained without anti-reflection coating (ARC), and it would be higher than 32% by ARC integration. The mass density of the 4 J flexible solar cell was only 467 g/m2, and the specific power was up to 550 W/kg.
关键词： Flexible,Aluminum (Al)-contained material,Inverted metamorphic (IMM),Four-junction solar cell
更新于2025-09-16 10:30:52
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Surface dynamic deformation of LY2 aluminum alloy subjected to a laser shock wave planishing technique with different kinds of contacting foils
摘要： In this paper, a laser shock wave planishing technique (LSWP) was used to treat the LY2 aluminum alloy surface with corrugated structures, and the influence of contacting film material on the planishing effect was studied. The dynamic response characteristics of surface micro-features under different physical parameters of contacting foils were simulated by finite element simulation (FEM), and experimental verification was carried out. A close match between the experimental results with these simulation results in FEM was found. The planishing of surface micro-protrusions can reduce the surface roughness of treated sample, and the lifting of bottom materials can ensure the surface profile accuracy. The results demonstrate that the planishing effect on micro-protrusions improves with the density of the contacting foil decreasing; The lifting effect on the bottom material enhances with the strength of the contacting foil increasing. A high modulus of elasticity contacting foil also facilitates the bottom material bulging.
关键词： Micro-features,Aluminum alloy,Finite element modeling,Surface topography,Laser shock wave,Dynamic response
更新于2025-09-16 10:30:52
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Influence of the laser-based surface modification on the bond strength for friction press joining of aluminum and polyethylene
摘要： Friction press joining is an innovative joining process for the production of plastic-metal joints without additives, in an overlap configuration. In order to achieve a high bond strength, the metallic joining partner is pretreated with laser radiation. Subsequently, heat is induced by friction and pressure during the joining process, causing the thermoplastic material to melt and adhere to the metallic joining partner. In this work, the temperature distribution during the process in the composite is analyzed and characterized. It was found that the occurring temperatures and temperature differences are not only dependent on the rotational speed, but also on the feed rate. It is also shown that the friction surface temperature can be used as an indirect control variable for a model-based, closed-loop control. Based on these findings, various surface modifications for the metallic joining partner were investigated and analyzed with regard to the maximum strength of the joint. It was observed that the highest tensile shear strength can be achieved with a quasi-chaotic nano structure. In addition, the joining compound was characterized by a thin section, facilitating the identification of specific zones in the joint. These investigations show the high potential for friction press joining of plastics and metals, and form the basis for a model-based control of the joining zone temperature.
关键词： Polymer metal joining,Dissimilar material joining,Aluminum,Hybrid bonds,Thermoplastics,Friction press joining
更新于2025-09-12 10:27:22
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Successful Treatment of Cosmetic Eyebrow Tattoos in Fitzpatrick III‐IV With Picosecond (1,064, 532‐nm) Neodymium‐Doped Yttrium Aluminum Garnet Laser With a Perfluorodecalin‐Infused Patch: A Pilot Study
摘要： Background and Objectives: Nanosecond Q‐switched lasers have been used for the removal of traditional and cosmetic tattoos. Picosecond lasers utilize pulse durations of 10?12 and provide more efficient clearance of tattoos. Safe and effective removal of tattoos is especially important in cosmetically sensitive areas such as the face. We report four patients with skin types (III–IV) who have had successful removal of eyebrow tattoos with the picosecond (1,064‐, 532‐nm) laser using a perfluorodecalin‐infused patch (PFD). Study Design/Materials and Methods: Patients with eyebrow tattoos underwent treatment with dual‐wavelength picosecond Nd:YAG laser at 1,064‐nm with a 3 mm spot size and fluence of 4–4.6 J/cm2. The 532‐nm wavelength was also used during treatment #1 (patient 2 only) with a 4 mm spot size and fluence of 0.5 J/cm2. Patient 1 had a total of three treatments (6–8 weeks apart). The remaining patients, each had only one treatment. Patients were photographed prior to treatment and subsequently at each follow‐up. Results: Immediately following each laser treatment, only mild and transient localized erythema and edema was observed. Some epidermal crusting was noted for 3–5 days following each treatment. Eyebrow hair growth was not affected and no adverse events were reported. There was 75% clearance in patient 1 after three treatments over a period of 2.5 months, 75% clearance in patient 2 after one treatment, 90% clearance in patient 3 after one treatment, and 100% clearance in patient 4 after one treatment. Conclusions: The 532‐ and 1,064‐nm wavelength of the picosecond Nd:YAG laser was safely used to clear brown and black ink eyebrow tattoos in four patients, three of whom were skin type IV, and one of whom underwent eyebrow tattoo via microblading, a novel and popular technique for cosmetic tattoos. The use of picosecond laser provides several treatment advantages to Q‐switched laser when treating eyebrow tattoos. In our experience, it required less number of treatments and lower fluences. This, along with use of the perfluorodecalin‐infused patch resulted in excellent outcomes for our patients with no significant side effects.
关键词： microblading,Nd:YAG,permanent makeup,picosecond,cosmetic tattoos,eyebrow tattoo,neodymium‐doped yttrium aluminum garnet
更新于2025-09-12 10:27:22
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A 271.8 nm deep-ultraviolet laser diode for room temperature operation
摘要： We present a deep-ultraviolet semiconductor laser diode that operates under current injection at room temperature and at a very short wavelength. The laser structure was grown on the (0001) face of a single-crystal aluminum nitride substrate. The measured lasing wavelength was 271.8 nm with a pulsed duration of 50 ns and a repetition frequency of 2 kHz. A polarization-induced doping cladding layer was employed to achieve hole conductivity and injection without intentional impurity doping. Even with this undoped layer, we were still able to achieve a low operation voltage of 13.8 V at a lasing threshold current of 0.4 A.
关键词： room temperature operation,aluminum nitride substrate,deep-ultraviolet,laser diode,polarization-induced doping
更新于2025-09-12 10:27:22
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Adhesion‐Engineering‐Enabled “Sketch and Peel” Lithography for Aluminum Plasmonic Nanogaps
摘要： Aluminum is one of the most significant plasmonic materials for its advantage of low cost, natural abundance, as well as the ultraviolet optical response. However, it is still very challengeable for the fabrication of aluminum plasmonic nanogaps, which greatly limits the applications of aluminum plasmonics considering the essential role of nanogaps for electric field enhancement. Here, the reliable patterning of aluminum plasmonic nanogaps employing a modified “Sketch and Peel” lithography strategy is demonstrated. By introducing a self-assembled monolayer to engineer the surface energy of the substrate, the adhesiveness of the aluminum film outside outline template is significantly decreased to implement the selective peeling process. Besides, the near-infrared Fano resonance in the periodic aluminum heptamers has been first revealed by enabling the strong electric field and plasmon coupling in the aluminum nanostructures with 10 nm scale nanogaps. In addition, surface-enhanced Raman spectroscopy and infrared spectroscopy are also illustrated in the rationally designed aluminum dimers. The present work provides a robust method to obtain aluminum plasmonic nanogaps, which may play an important role on the practical applications of aluminum plasmonics, such as surface-enhanced vibration spectroscopy and nonlinear optics.
关键词： surface-enhanced spectroscopy,aluminum plasmonics,Sketch and Peel lithography,adhesion engineering,plasmonic nanogaps
更新于2025-09-12 10:27:22
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Effect of adherend deflection on lap-shear tensile strength of laser-treated adhesive-bonded joints
摘要： Laser surface treatment was used as a surface preparation method for adherend prior to adhesive bonding, which significantly improved the fracture mode from mixed to cohesive and consequently increased the lap-shear tensile strength by 27.5% and 28.2% for aluminum alloys AA7075 and AA6022 adhesive-bonded joints, respectively. Nevertheless, the laser-treated AA7075 joint exhibited a ~14% higher strength compared to laser-treated AA6022 joint although both joints showed cohesive fracture modes, which was attributed to smaller adherend deflection of laser-treated AA7075 joint than that of laser-treated AA6022 joint. Digital image correlation technique was applied to monitoring the deflections of laser-treated AA7075 and AA6022 joints during lap-shear tensile testing, and the stress analysis of adhesive-bonded lap-shear joints was conducted by finite element simulation. It was found that the deflection angle of the laser-treated AA6022 joint reached to 6.1° at the peak tensile load and was ~69% larger than that of laser-treated AA7075 joint (i.e. 3.6°), which resulted in a mixed stress state with higher peel stress (i.e. ~8 MPa) on edges of adhesive bonding region and consequently led to a premature fracture due to the low peel resistance of adhesive-bonded joints. Furthermore, the effect of decreased adherend deflection on lap-shear tensile strength was investigated, and a linear increase of lap-shear tensile strength was found with the decrease of deflection angle for adhesive-bonded joints showing cohesive fracture modes.
关键词： finite element stress analysis (C),lap-shear tensile strength (C),laser surface treatment (B),aluminum alloys (B),adherend deflection
更新于2025-09-12 10:27:22
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Influence of the degree of dilution with laser beam vacuum-welded Cu-Al mixed joints on the electrical properties
摘要： A great potential for light-weight construction lies in the substitution of copper by aluminum. The state of the art, so far, has put the focus only on the identification of the crack-sensitive intermetallic phase. External influential factors, such as temperature, current-feed and time bring about the change of the joining zone structure by diffusion and electro-migration. Moreover, a temporal change of the technological properties (increase of the electric resistance, reduction of strength) of the dissimilar material joint will occur. Findings about this behavior for laser beam under vacuum welds will allow to draw conclusions about the expected life-time.
关键词： Laser beam welding,Dissimilar material joint,Single-moder fiber laser,Copper,Aluminum
更新于2025-09-12 10:27:22
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Influence of welding angle on the weld morphology and porosity in laser-arc hybrid welding of AA2219 aluminum alloy
摘要： The influence of welding angle on weld morphologies and porosity characteristics was studied in laser-arc hybrid welding of AA2219 aluminum (Al) alloy. The upward sloping and vertical weld (USVW) was performed better than the downward sloping and vertical weld (DSVW). The high-speed camera was used to observe the welding process. It is found that the welding process becomes stable when the transitional position of the droplet was 2 mm away from the keyhole. By analyzing the force act on keyhole and characteristics of the pool, it is found that the weld morphologies and porosity characteristics were associated with gravity-laser angle (β), which affects the keyhole stability and characteristics of the pool. The results showed that the flow velocity was accelerated when the β increased, which was a benefit for decreasing porosity. This is because the gravity in the direction of the welding accelerates the pool flow. Due to the increasing of the β, the static pressure and the vapor pressure in the keyhole were increased, which improved the stability of the keyhole and decreased the porosity.
关键词： Keyhole,Weld morphology,Porosity,Aluminum alloy,Laser-arc hybrid welding
更新于2025-09-12 10:27:22
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Laser metal deposition of bionic aluminum supports: reduction of the energy input for additive manufacturing of a fuselage
摘要： Additively manufactured components made of metallic material are subject to special consideration for many R&D departments, since the process control is not yet sufficiently reliable and therefore an extensive quality assurance is necessary. For this reason, few structural components for aviation have been established so far. In this paper, a feasibility study for the use of laser metal deposition (LMD) for the additive manufacturing of a fuselage made of aluminum is carried out. The result is a parameter set with a minimized energy input. However, due to a welding length of 58 m the overall energy input is high and large distortion arises.
关键词： aluminum,additive manufacturing,laser metal deposition,aerospace,bionic
更新于2025-09-12 10:27:22