Laser Scribing Method Research Articles

Laser Precise Synthesis of Oxidation-Free High-Entropy Alloy Nanoparticle Libraries.

High-entropy alloy nanoparticles (HEA-NPs) show exceptional properties and great potential as a new generation of functional materials, yet a universal and facile synthetic strategy in air toward nonoxidized and precisely controlled composition remains a huge challenge. Here we provide a laser scribing method to prepare single-phase solid solution HEA-NPs libraries in air with tunable composition at the atomic level, taking advantage of the laser-induced metastable thermodynamics and substrate-assisted confinement effect. The three-dimensional porous graphene substrate functions as a microreactor during the fast heating/cooling process, which is conductive to the generation of the pure alloy phase by effectively blocking the binding of oxygen and metals, but is also beneficial for realizing accurate composition control via microstructure confinement-endowed favorable vapor pressure. Furthermore, by combining an active learning approach based on an adaptive design strategy, we discover an optimal composition of quinary HEA-NP catalysts with an ultralow overpotential for Li-CO2 batteries. This method provides a simple, fast, and universal in-air route toward the controllable synthesis of HEA-NPs, potentially integrated with machine learning to accelerate the research on HEAs.

Laser‐Induced Graphene Toward Flexible Energy Harvesting and Storage Electronics

AbstractEnergy harvesting and storage devices play an increasingly important role in the field of flexible electronics. Laser‐induced graphene (LIG) with hierarchical porosity, large specific surface area, high electrical conductivity, and mechanical flexibility is an ideal candidate for fabricating flexible energy devices which supply power for other electronic components. Through a simple laser irradiation process with designable routes, abundant precursors (or substrates) rapidly transform into patterned LIG without any other treatments. The structure and physicochemical properties of LIG can be regulated by controlling the processing strategies and parameters, enabling the optimization of device performance. The laser scribing method, as a non‐contact and in situ technique, proves to be efficient in integrating different LIG‐based devices, resulting in all‐in‐one flexible power platforms. Here, a systematic summary of recent advancements in LIG‐based flexible energy electronics is presented. The controllable synthesis of LIG, functional LIG, and 3D architectures are described by elucidating corresponding mechanisms and processing strategies. An overall review of flexible energy conversion and storage devices based on LIG is presented. Eventually, the challenges and opportunities of LIG‐based materials in flexible energy conversion and storage are briefly discussed.

Functional Piezoresistive Polymer Composites Based on CO2 Laser-Irradiated Graphene Oxide-Loaded Polyurethane: Morphology, Structure, Electrical and Piezoresistive Properties

Nanocomposite materials have recently attracted great attention for their wide range of applications, such as in smart materials, flexible electronics, and deformation sensing applications. Such materials make it possible to combine a polymer with functional fillers. In this study, flexible artificial leathers, exhibiting insulating properties and containing 1.5 or 2wt.% of graphene oxide (GO) in the polyurethane (PU) layer, were electrically activated via CO2 laser irradiation to obtain conductive paths at the surface exposed to the laser beam. As the material retained its insulating properties out of the irradiation areas, the laser scribing method allowed, at least in principle, a printed circuit to be easily and quickly fabricated. Combining a variety of investigation methods, including scanning electron microscopy (SEM), optical profilometry, IR and Raman spectroscopies, and direct current (DC) and alternate current (AC) electrical measurements, the effects of the laser irradiation were investigated, and the so-obtained electrical properties of laser-activated GO/PU regions were elucidated to unveil their potential use in both static and dynamic mechanical conditions. In more detail, it was shown that under appropriate CO2 laser irradiation, GO sheets into the GO/PU layer were locally photoreduced to form reduced-GO (RGO) sheets. It was verified that the RGO sheets were entangled, forming an accumulation path on the surface directly exposed to the laser beam. As the laser process was performed along regular paths, these RGO sheets formed electrically conductive wires, which exhibited piezoresistive properties when exposed to mechanical deformations. It was also verified that such piezoresistive paths showed good reproducibility when subjected to small flexural stresses during cyclic testing conditions. In brief, laser-activated GO/PU artificial leathers may represent a new generation of metal-free materials for electrical transport applications of low-current signals and embedded deformation sensors.

Laser-induced porous graphene from PEDOT:PSS films for dye-sensitized solar cells

• 3D porous graphene was firstly fabricated from PEDOT:PSS by a laser-scribing method. • Sheet resistance and morphology of LIG can be easily tuned by changing laser power. • LIG shows enhanced photovoltaic performance as a counter electrode for DSSCs. For the emerging laser-induced graphene (LIG) technologies, the exploration of laser irradiation interactions with various polymers and their new applications remains challenging. Herein, we report a novel strategy for the fabrication of 3D porous graphene electrodes from the aqueous PEDOT:PSS dispersion by a 445-nm diode laser in ambient air. By adjusting the laser power, LIG films exhibit a sheet resistance as low as 50 Ω/sq and their morphologies can change from a carbonized surface to a hierarchical porous structure. The dye-sensitized solar cell with a LIG70 counter electrode achieved a power conversion efficiency of 3.66%, which is over four times that of the pristine PEDOT:PSS electrode (0.80%). This work demonstrates the great potential for the application of PEDOT:PSS-based LIG films in photovoltaic devices.

Facile fabrication of reduced graphene oxide counter electrodes by laser engraver for dye-sensitized solar cell applications

Exploring alternative Pt-free counter electrode with low cost and high electrocatalytic activity is always a main focus at the frontier of dye-sensitized solar cells (DSSCs). In this study, a desktop laser engraver was applied to reduce graphene oxide (GO) film on a fluorine-doped tin oxide (FTO) substrate, and the obtained graphene-based material was further used as counter electrode for DSSC. Additionally, this facile laser-scribing method was also adopted to fabricate a prototype of composite electrode via the combination of reduced graphene oxide (RGO) and carbon black (CB) to enhance the specific surface area and active sites. A variety of characterizations including scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to investigate the microstructures and catalytic properties of these carbon electrodes. The findings reveal that both of the DSSCs with laser-scribed carbon electrodes show evidently increasing photovoltaic performance, and the DSSC based on RGO/CB composite electrode even presents a higher power conversion efficiency (PCE) of 4.49%, comparable to 4.14% of the conventional Pt-based DSSC.

Laser-induced MnO/Mn3O4/N-doped-graphene hybrid as binder-free anodes for lithium ion batteries

Rational design and scalable construction of unique three-dimensional structures with high electronic conductivity and small volume changes upon repeated cycles are challenging. Here, laser-induced MnO/Mn3O4/N-doped-graphene (MNLIG) hybrid frameworks as binder-free anodes are firstly demonstrated for Li-ion batteries. The one-step laser scribing technique is applied to produce MNLIG hybrids in-situ anchored on Cu current collectors, which is facile and controllable. It is shown that the resultant MNLIG composites perform exceptionally well as Li-ion batteries anode, specifically, a high reversible capacity of 992 mAh g−1 at 0.2 A g−1 and excellent rate capacity of 365 mAh g−1 at 2.0 A g−1, as well as a high cycling stability (699 mAh g−1 after 400 cycles at 0.2 A g−1) were achieved. It’s proposed that the homogeneous distribution of MnO/Mn3O4 nanoparticles on surfaces of nitrogen-doped graphene (NLIG) as well as the dense architecture account for excellent electrochemical performances of as-designed framework electrodes. The laser scribing method enable quick fabrication of graphene-based hybrid frameworks directly anchored on current collectors, which can also scale up and holds promising application prospect in energy storage.

Hybridization of MOFs and graphene: A new strategy for the synthesis of porous 3D carbon composites for high performing supercapacitors

A novel porous 3D-structured carbon composite material with a unique architecture by combining graphene and carbonized metal-organic framework (C-MOF) (HKUST-1) microrods for high performing supercapacitors has been synthesised and characterised. The HKUST-1 microrods were prepared by a new method, converting their diamond-like shape into microrods via mechanical shear mixing in an aqueous solution. Grinding of HKUST-1 and graphene oxide (GO) resulted in the formation of a 3D GO-MOF composite with intercalated HKUST-1 microrods between GO sheets. The composite film was treated by a laser scribing method and created a highly porous, a high surface area (>600 m2/g) and conductive 3D nanostructured composite film (L-rGO-C-MOF) used as electrodes for supercapacitor applications. The prepared film showed a high capacitance of 390 F/g at 5 mV/s, and a cyclic stability of 97.8% at 10 A/g after 5000 cycles. The symmetrical supercapacitor delivered an excellent power density of 8037.5 W/kg with an outstanding energy density of 22.3 Wh/kg confirming a new pathway to design new 3D porous graphene-MOF composites for high-performance energy storage devices.

A Laser Scribed Graphene Oxide and Polyimide Hybrid Strain Sensor

Strain sensors are devices used in applications such as electronic skin, prosthetic limbs, and e-textile applications, etc., for the purpose of measuring the physical elongation of a desired structure under a given or applied force. An artificial throat, using a strain sensor, was recently developed as an aid for speech impaired individuals. Strain sensors have been developed using graphene and polydimethylsiloxane (PDMS), with a reported gauge factor ranging from (5~120). We have developed a strain sensor through laser scribing. Using laser scribing is a recent and facile technology, used for printed electronics. Complex geometries and patterns can be drawn very easily using this method. The laser scribing method relies on the property of certain materials to form a graphene-like conductive material upon irradiation by lasers. Polyimide and graphene oxide (GO) are two such materials.In these experiments, 2×2 cm sheet of polyimide were taken and printed 1×1 cm box on the sheet using a laser patterning setup of 450 nm wavelength. Graphene oxide solution was drop-casted on the reduced polyimide sheet of 1×1cm, to increase its sensitivity, and then the drop-casted graphene oxide was reduced using the same laser. The strain sensor was characterized by a micro-strain testing machine. The normalized resistance was plotted against strain and the gauge factor was calculated. The effect of the laser intensity was investigated and different gauge factors were calculated by varying the intensity of the laser. The gauge factors were found to be in the range of 49-54 and was compared with the polyimide reduced strain sensor (without drop-casting the GO).

Fabrication of Graphene Supercapacitors for Flexible Energy Storage

In the present work, graphene powder was synthesized by laser scribing method. The resultant flexible light-scribed graphene is very appropriate for use in micro-supercapacitors. The effect of the laser scribing process in reducing graphene oxide (GO) was investigated. GO was synthesized using a chemical mixture of GO solution; then, it was coated onto a LightScribe DVD disk and laser scribed to reduce GO and create laser-scribed graphene (LSG). The CV curves of pristine rGO at various scan rates showed that the ultimate product possesses the ability to store energy at the supercapacitor level. Charge-discharge curves of pristine rGO at two different current densities indicated that the specific capacitance (Cm) increases due to the reduction of the discharge current density. Finally, the long-term charge-discharge stability of the LSG was plotted and indicates that the specific capacitance decreases very slightly from its primary capacitance of ~10F cm−3 and that the cyclic stability is favorable over 1000 cycles.

Laser scribing of CIGS thin-film solar cell on flexible substrate

Laser scribing technology has been actively developed for thin-film solar cell fabrication taking a number of advantages over mechanical scribing. Its non-contact processing nature enables reliable and precise scribing processes. In particular, it is almost unavoidable to use laser scribing method for fabricating high-quality flexible thin-film solar cells. Despite the fundamental merits that laser scribing can offer, still a number of challenges should be addressed in order to replace the mechanical counterpart for wider range of thin-film solar cells. In this study, we explore optimal laser scribing conditions for copper–indium–gallium–selenide (CIGS) thin-film solar cells, especially based on flexible polyimide (PI) substrate in close comparison with that based on soda-lime glass substrate. Picosecond-pulsed laser of repetition rate up to 100 kHz and wavelength of 532 nm (~12 ps temporal pulse width) was mainly tested, and scribing speed in the range of 0.01–1 m/s was examined with a few different laser focal spot diameters (27, 34, and 62 μm). Main focus of this study is in understanding distinct laser scribing mechanisms for flexible substrate configurations, thereby finding out intrinsic optimal processing parameters. One of the most critical requirements is to prevent possible damage or deformation of underlying thin-film layer(s) or PI substrate. Effect of microstructures of thin films (in particular, Mo and CIGS) on the scribing behavior was also examined. In order to further improve the performance of the scribing process and reduce the laser power budget as well, mild gas injection scheme was tested.

Solar photovoltaic technology on rough low carbon steel substrates for building integrated photovoltaics: A complete fabrication sequence

The purpose of this paper is to show an innovative and complete fabrication sequence of thin film photovoltaic modules based on hydrogenated amorphous silicon on non transparent substrates (high roughness low carbon steel). This fabrication sequence is oriented to monolithically interconnected modules with two main challenges (i) the development of surface treatment technology (low cost intermediate inorganic coatings based on sol–gel technology) for the deposition of thin film solar cells on non transparent substrates and (ii) the use of novel laser scribing methods in substrate configuration. After the research carried out in this work, we demonstrate that (i) surface treatment technology has been successfully developed proving its good behavior in 1cm2 steel solar cells achieving efficiencies close to 7%, and (ii) laser scribing method has also been succeeded achieving efficiencies higher than 3% in 64cm2 modules. Electrical losses due to these processes have been evaluated. It is important to point out that, although silicon based technology has been used, these advances are not directly related to any specific thin film solar technology, being suitable for CIGS and CdTe solar cells.

Enhanced electrochemical performance of laser scribed graphene films decorated with manganese dioxide nanoparticles

High-performance supercapacitor electrode films of laser scribed graphene (LSG) decorated with manganese dioxide (MnO2) are produced on flexible substrates by two methods. One composite film of small diameter MnO2 particles directly added into graphene oxide sheets is reduced by a facile laser scribing technology. The other composite film is fabricated by in situ synthesis and laser scribing technology. The as-prepared films are characterized by Fourier transform infrared spectrum, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. Cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charging–discharging techniques are carried out to test the electrochemical performances. Film fabricated by in situ synthesis and laser scribing method displays much improved electrochemical properties. The volumetric capacity is as high as 202.98 F/cm3. The film also exhibits excellent charge/discharge rate and good cycling stability, retaining 91.2 % of its initial charge after 5500 cycles. The enhanced electrochemical performance benefits from facile preparation method and magnified synergetic effect. Furthermore, the volumetric density of laser scribed graphene/MnO2-microsupercapacitor achieves 2.59 mWh/cm3, which is approximately three times higher than that of LSG-microsupercapacitor unit. Such composite film indicates a promising future as electrode material for electrochemical energy storage devices.

Reliable fabrication process for long-length multi-filamentary coated conductors by a laser scribing method for reduction of AC loss

We have developed a reliable fabrication process based on a laser scribing method for multi-filamentary coated conductors with a low alternating current loss. This process consists of shallow laser irradiation and two-step chemical etching. The shallow laser irradiation, which penetrates into only a masking polymer tape and a silver stabilizing layer, suppresses generation of dross that is formed due to melting and hardening of a metal substrate. The two-step chemical etching individually for the stabilizing and the superconducting layers prevents over-etching of the superconducting layer and thus suppresses degradation of the critical current (Ic). By using the developed laser scribing process, we realized an improvement of processing speed and a reduction of Ic degradation at the same time. Subsequently, we developed reel-to-reel equipment to apply this process to coated conductors several hundred meters long. We succeeded in fabricating 280 m and 70 m long coated conductors with 5 mm width divided into three and five filaments, respectively. It was confirmed that they had one-third and one-fifth hysteresis loss, respectively, in comparison with that before processing, and high inter-filament resistance, over 0.1 MΩ cm. The typical degradation rates of Ic in the developed laser scribing process were less than 20%.

Laser Scribing of W-textured ZnO Substrates Using Green Laser

ABSTRACTThin-film silicon solar cells have been attracted a lot of intention as low-cost solar cells. One of the most important technologies for improving their performances is light trapping. We have demonstrated the high potential of double-textured zinc oxide (ZnO) thin films used as front transparent conductive oxide (TCO) films due to further enhancement of their light-trapping effects. Although the laser scribing method has already been well established for low-cost thin-film silicon solar cell module manufacturing, laser scribing technique on double-textured ZnO is new and still a challenging issue. In this study, we firstly demonstrated the availability of laser scribing for amorphous silicon (a-Si) solar cells fabricated on double-textured ZnO substrates. It is general to utilize lasers with wavelength of 1.06 μm and 532 nm for scribing of TCO and silicon layer, respectively. Here we attempted to scribe both of TCO and silicon layers using a 532 nm wavelength laser (green laser) for process simplifying.

Over-current characteristics of model coil using Y-based multi-filament wire for superconducting power transformers

In the Japanese national project to develop superconducting power applications using Y-based coated conductors, the present focus is on various aspects of technological development of superconducting power transformers. Since Y-based multi-filament wire contributes to reduction in AC loss of superconducting transformer coils, a 5mm-wide long-length multi-filament, between the filaments of 3 and 5, has been developing by a laser scribing method. In the case of the project target, a 66kV/20 MVA power transformer coils require a Y-based multi-filament wire between the lengths of 200m and 300m. It also must withstand over-current of about seven times the rated current, which is generated when a power system fault occurs. In this paper, over-current characteristics of model coil using Y-based 3-filament wire were evaluated.

Investigation of core loss characteristics of 3% SiFe using the laser scribing method

AbstractThe core loss of 3% SiFe is strongly dependent on silicon content, impurities, permeability, and domain structure of the SiFe. Domain refining has proved to be a very good method for the reduction of core loss in high‐permeability grain‐oriented SiFe, and laser scribing is well known as an effective and industrially important method of domain refinement. In this work, magnetic domain refinement was carried out using a pulsed and Q‐switched Nd:YAG laser, and the core losses were measured and analysed to find the optimal parameters of the laser treatment. The laser beam was focused with a spot size of 0.2 mm and pulse energy of 15–30 mJ and the lines were scribed with a period of ∼5 mm. The core loss was improved by up to 18% in 3% SiFe using this method, and the loss was relatively insensitive to the optical energy of the Q‐switched pulse. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Diode laser scribing of non-oriented 3 wt% Si-steel for core loss reduction

The electrical power industries are experiencing a considerable energy loss in transformers and motors because of inefficiencies caused by core loss. The objective of our research is to investigate any effect of laser scribing on the reduction of the core loss in the low cost, non-oriented steels used in numerous utility applications. A 15 W diode laser transmitted through fiber optics was used to scribe 0.35 mm thick, non-oriented 3 wt% Si steel. The magnetic properties including the core loss and permeability were evaluated both before and after laser scribing. A maximum core loss reduction of 0.08 W kg−1 at a magnetic induction of 1 T and a 21% increase in relative permeability were obtained at the optimum laser parameters. These results are comparable to those of laser scribed, expensive grain-oriented steels. The core losses were further reduced using a treatment procedure consisting of laser scribing, chemical etching, and stress relief annealing performed in sequence. The laser scribing method is simpler, energy efficient, and can be implemented in the production line.

Improvement of magnetic properties in thinner HI-B with domain-refinement

The domain-refinement technique which was developed to decrease anomalous eddy-current loss showed remarkable effect. The LASER-scribing method enabled the development of industrial products. Moreover, when this domain-refinement was applied to thinner gaged core material, the effect appeared in a marked degree. In this paper, the improvement of magnetic Properties of 0.23mm thick domain-refined core material is emphasized, because it has been used widely. It was clarifyed that the effect of domain-refinement depended on the thickness of core materials and the induction at 1000A/m strongly. The core losses, 0.80W/kg at 1.7T, 50Hz and 0.59W/kg at 1.5T, 50Hz were successfully obtained for an industrial product, 0.23mm HI-B. When the LASER-scribing was applied to very high permeability HI-B, the hysteresis loss was little changed, but the eddy-current loss decreased sharply. Further, by the numerical analysis with actually measured data, the Building Factor was also improved by the patterns of the LASER-scribing.

End preparation and fusion splicing of an optical fiber array with a CO_2 laser

Mirror-finished end preparation and low-loss splicing of silica fiber arrays by means of a CO(2) laser are demonstrated. Eight-fiber linear arrays of multimode fibers with 60-microm core diam and 150-microm outer diam were laser scribed and fractured, then butted and spliced with 3.0-W laser power output, 1.0-mm beam-spot diam, and 15-microm/sec fiber array driving speed. Average splice losses for 20x splicings (160 splices) in step- and graded-index fibers were 0.12 db and 0.10 dB, respectively. The air bubbles sometimes observed at the splicing point in fusion splices were avoided by preparing fiber ends with a laser-scribing method.