Piezoelectric thin films have become increasingly significant in applications such as MEMS devices, wearable electronics, and lab-on-a-chip systems due to the miniaturization and integration of electronic devices. For piezoelectric thin films, even when an electric signal is applied in the thickness direction, greater deformation can often be observed in the in-plane direction, which is perpendicular to the electric field. Therefore, piezoelectric thin film devices are frequently designed using the transverse mode. As a result, it is crucial to evaluate piezoelectric thin films by measuring their transverse piezoelectric coefficient. This tutorial paper introduces a method for evaluating the effective transverse piezoelectric coefficient (e31,f) of piezoelectric thin films using laser Doppler vibrometry (LDV). Additionally, the paper outlines a step-by-step procedure for measuring e31,f while using Bi1/2Na1/2TiO3-based piezoelectric thin films as an example. This tutorial is expected to provide a practical and valuable method for measuring and analyzing the transverse piezoelectric properties, thereby supporting the development of new piezoelectric thin film materials.
The laser (LASER), originating from the principle of stimulated emission proposed by Albert Einstein, has been a catalyst for substantial advancements across numerous industrial and scientific domains. Initially confined to research and laboratory applications, the scope of laser technology has expanded rapidly over time. This expansion is primarily due to the laser's unique characteristics, such as high-density energy output and precise beam control, which have facilitated its widespread integration into contemporary industrial practices. Specifically, laser materials processing technology enables the machining of diverse materials, including metals, ceramics, and polymers, in a non-contact manner, thereby achieving high precision without the risk of wear or contamination. As a result, laser processing has become indispensable in fields such as advanced electronics manufacturing, medical device production, aerospace, and the automotive industry. Furthermore, laser materials processing exhibits significant potential for high-precision applications that demand minimal thermal deformation of materials, such as microfabrication and the production of complex geometries. This paper provides a comprehensive examination of the development and necessity of laser processing technology, explores various laser types and their possible applications, and elucidates why laser technology has emerged as a fundamental component of modern manufacturing, alongside its trajectory for future development.
One method to increase the output of solar modules is the application of the Half-cut technique, which requires a scribing process involving direct irradiation of infrared lasers on the solar cells. During this process, the laser melts the surface of the solar cells at high temperatures, enabling mechanical division, but this can lead to output loss due to thermal degradation caused by the laser. To minimize such losses, a low-temperature and low-loss division method has been devised. In this study, we compared the electrical characteristics and leakage currents affecting output degradation between the newly devised low temperature and low-loss cell division method and the conventional laser division method. Additionally, we conducted a 3-point flexural test to evaluate the mechanical properties of both methods.
Laser-induced plasmonic sintering of metal nanoparticles (NPs) holds significant promise as a technology for producing flexible conducting electrodes. This method offers immediate, straightforward, and scalable manufacturing approaches, eliminating the need for expensive facilities and intricate processes. Nevertheless, the metal NPs come at a high cost due to the intricate synthesis procedures required to ensure long-term reliability in terms of chemical stability and the prevention of NP aggregation. Herein, we induced the self-generation of metal nanoparticles from Ag organometallic ink, and fabricated highly conductive electrodes on flexible substrates through laser-assisted plasmonic annealing. To demonstrate the practicality of the fabricated flexible electrode, it was configured in a mesh pattern, realizing multi-touchable flexible touch screen panel.
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Controlling Structures and Properties of NaCl‐Containing Alginate/Polyacrylamide Tough Hydrogels via a One‐Pot Process Taeuk Eom, Hyunseung Kim, Jihun Choi, Soon Joo Yoon, Yoon Kyeung Lee, Kwi‐Il Park, Chang Kyu Jeong Chemistry – A European Journal.2026;[Epub] CrossRef
Wearable sweat glucose monitoring patches enabled by double network hydrogel-MoS2/PEDOT: PSS nanocomposite Suraj Shinde, Omkar A. Patil, Sang Yoon Park, Se Jin Choi, Omkar Pawar, Daniel J. Joe, Sooman Lim, Han Eol Lee Microchemical Journal.2025; 215: 114309. CrossRef
Perovskite materials are promising candidates for next-generation optoelectronic devices owing to their outstanding external quantum efficiency, high color purity, and ability to tune the light emission wavelength. However, conventional thermal annealing processes caused the degradation of perovskite, resulting in poor optoelectronic properties and a short lifetime. Herein, we propose a laser-induced recrystallization of perovskite thin film to enhance its light-emitting properties. Laser-induced recrystallization process was performed using rapid and instantaneous laser heating, which successfully induced grain growth of the perovskite material. The laser processing conditions were thoroughly optimized based on theoretical calculations and various material analyses such as x-ray diffraction, scanning electron microscope, and photoluminescence spectroscopy.
Owing to carbon materials’ diverse functionalization and versatility, the design and synthesis of carbon-based three-dimensional porous structures have become important foundational research topics across various fields. Among the various methods for producing porous carbon structures, laser-induced graphene (LIG) has garnered attention because of its large surface area, controllable structure, excellent electrical conductivity, scalability, and eco-friendly synthesis process. In addition, recent research results have reported more novel functionalities by advancing further from the unique characteristics of LIG through functionalization or compounding of LIG, making it an attractive material for various applications in electronic devices, sensing, catalysis, and energy storage. This review aims to update the research trends in LIG and its functionalization, providing insights to inspire more interesting studies on functional LIG to expand its potential applications ultimately. Starting with the synthesis method and material characteristics of LIG, we introduce the functionalization of LIG, which is classified into surface modification, heteroatom doping, and hybridization based on the interaction mechanism. Finally, we summarize and discuss the prospects of LIG and its functionalization.
Laser-induced plasmonic sintering of metal nanoparticles (NPs) is a promising technology to fabricate flexible conducting electrodes, since it provides instantaneous, simple, and scalable manufacturing strategies without requiring costly facilities and complex processes. However, the metal NPs are quite expensive because complicated synthesis procedures are needed to achieve long-term reliability with regard to chemical deterioration and NP aggregation. Herein, we report laser-induced Ag NP self-generation and sequential sintering process based on low-cost Ag organometallic material for demonstrating highquality microelectrodes. Upon the irradiation of laser with 532 nm wavelength, pre-baked Ag organometallic film coated on a transparent polyimide substrate was transformed into a high-performance Ag conductor (resistivity of 2.2 × 10-4 Ω·cm). To verify the practical usefulness of the technology, we successfully demonstrated a wearable transparent heater by using Ag-mesh transparent electrodes, which exhibited a high transmittance of 80% and low sheet resistance of 7 Ω/square.
In this paper, laser-induced fluorescence properties of four plastics were characterized through spectrometer analysis for real-time microplastic counting. Recently, environmental problems related to microplastics have emerged. In order to detect microplastics, analysis methods such as FT-IR and Raman are used. However, they have the disadvantages of being timeconsuming and requiring a pretreatment process. In most plastic products on the market, 10% to 30% of plasticizers and reinforcing agents are added. Therefore, most microplastics present in seawater and freshwater emit fluorescence signals by 270 nm UV light source regardless of their type due to their molecular structure due to additives. Real-time microplastics counting is possible more easily by using the proposed laser-induced fluorescence detection method because of the fluorescence expression characteristic of 340 nm that appears due to the plasticizer of plastics.
As packaging processes for atomic gyroscope vapor cells, the glass tube tip-off process, anodic bonding, and paste sealing have been widely studied. However, there are stability issues in the alkali metal which are caused by impurity elements and leakage during high-temperature processes. In this study, we investigated the applicability of a vapor cell low-temperature packaging process by depositing Au on a Pyrex cell in addition to forming an Au-Sn thin film on a cap to cover the cell, followed by laser irradiation of the Au/Au-Sn interface. The mechanism of the thin film bonding was evaluated by XRD, while the packaging reliability of an Ne gas-filled vapor cell was characterized by variation of plasma discharge behavior with time. Furthermore, we confirmed that the Rb alkaline metal inside the vapor cell showed no color change, indicating no oxidation occurred during the process.
The high power of a shingled photovoltaic module can be attributed to its low cell-to-module loss. The production of high power modules in limited area requires high efficiency solar cells. Shingled photovoltaic modules can be made by divided solar cells, which can be produced by the laser scribing process. After dividing the 21% PERC cell using laser scribing, the efficiency decreased by approximately 0.35%. However, there was no change in the efficiency of the solar cell having relatively lower efficiency, because the laser scribing process induce higher heat damages in solar cells with high efficiency. To prove this phenomena, the J0 (leakage current density) of each cell was analyzed. It was found that the J0 of 21% PERC increased about 17 times between full and divided solar cell. However, the J0 of 20.2% PERC increased only about 2.5 times between full and divided solar cell.
Recently, with the increase in the use of urban solar power, solar modules are required to produce high power in limited areas. In this report, we proposed the fabrication of a high-power photovoltaic module using shingles technology, and developed accurate string characteristic simulations based on circuit modeling. By comparing the resistance components between the interconnected cells and the cell strips, the ECA resistance was determined to be 0.003 Ω. Based on the equivalent circuit of the modeled shingled string, string simulation was performed according to the type of cell strip. As a result, it was determined that the cell efficiency of the 4-cell strip was the highest at 19.66%, but the efficiency of the string simulated with the 6-cell strip was the highest at 20.48% in the string unit.
Advances in laser technology have enabled ultra-high-speed ultra-precise processing, thus expanding potential applications to the semiconductor, medical, and photovoltaic industries. In particular, laser scribing technology has been applied to the production of shingled solar modules. In this work, we analyze the effect of laser scribing conditions, e.g., scribing depth, on the characteristics of the resulting divided solar cells. When the scribing depth was greater than 100 ㎛, the solar cells were well separated. In addition, the desired scribing depths were reached in fewer scans when the laser spot overlap was 100%. The efficiency of the divided cells decreased due to the high series resistance at scribing depths of less than 100 ㎛. However, at scribing depths of approximately 100 ㎛, the series resistance was low and efficiency reduction was minimized.
P(VDF-TrFE-CFE) (Poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)), which exhibits a high electrostriction of about 7%, can transmit tactile output as vibration or displacement. In this study, we investigated the applicability of P(VDF-TrFE-CFE) to wearable piezoelectric actuators. The P(VDF-TrFE-CFE) layers were deposited through spin-coating, and interspaced with patterned Ag electrodes to fabricate a two-layer 3.5 mm × 3.5 mm device. This layered structure was designed and fabricated to increase the output and displacement of the actuator at low driving voltages. In addition, a laser vibrometer and piezoelectric force microscope were used to analyze the device’s vibration characteristics over the range of ~200~4,200 Hz. The on-off characteristics were confirmed at a frequency of 40 Hz.
The ratio of the period of a diffractive element to the input beam size is a critical parameter in a diffractive beam shaper. We measured and calculated the Fraunhofer diffraction patterns of a periodic hologram with an input beam size similar to the period of the hologram. The measured intensities show very complicated patterns and are strongly dependent upon the center position of the laser beam relative to the hologram. Using a diffraction formula for a periodic hologram, we calculated the diffracted light intensities and fit them to the measured ones. The measured and calculated intensities are in good agreement even when the beam diameter of the incident laser is similar to the period of the hologram. We can therefore use this formula to estimate the output of a periodic beam shaper even under such an extreme condition.
In this study, a femtosecond laser pre-annealing technology based on indium zinc oxide (IZO) thin-film transistors (TFTs) was investigated. We demonstrated a stable pre-annealing process to analyze the change in the surface structures of thin-films, and we improved the electrical performance. Furthermore, static and dynamic electrical characteristics of IZO TFTs with n-channel inverters were observed. To investigate the static and dynamic responses of our solution-processed IZO TFTs, simple resistor-load-type inverters were fabricated by connecting a 1-MΩ resistor. The femtosecond laser pre-annealing process based on IZO TFTs showed good performance: a field-effect mobility of 3.75 cm2/Vs, an Ion/Ioff ratio of 1.8×105, a threshold voltage of 1.13 V, and a subthreshold swing of 1.21 V/dec. Our IZO-TFT-based N-MOS inverter performed well at operating voltage, and therefore, is a good candidate for advanced logic circuits and display backplane.
Hole explosion behaviors were observed during drilling fine holes with laser beam on the LTCC green bar of 320 ㎛ thick after lamination of green sheets prepared by tape casting of thick film process. The incidence of these hole explosions was inversely proportional to hole sizes. The incidence of hole explosion was 20 % number of hole with the size of 60 ㎛ exploded for the UV radiation, while the explosion did not appear for hole sizes over 100 ㎛. To prevent hole explosion behavior during laser-drilling of fine holes, carbon black powder was added as an additive in the LTCC composition, which has superior thermal durability. As a consequence, hole explosion rate was suppressed to 0.8 % for the hole size of 50 ㎛ green sheet with the carbon black amount of 10 weight % and the laser power of 3 watt. Added carbon is thought to reduce the heat-affected region during laser drilling.
ITO/Ag/ITO conductive films on PET (polyethylene terephthalate) was etched by a Q-switched diode-pumped neodymiun-doped yttrium vanadate (Nd:YVO4, λ = 1064 ㎚) laser. During the laser direct etching, the laser beam was incident on the two different directions of PET and the etching patterns were investigated and analyzed. At a lower repetition rate of laser pulse, the larger laser etched patterns were obtained by laser beam incident on reverse side of PET substrate. On the contrary, at a higher repetition rate, it was possible to find the larger etched patterns in case of the laser beam incidence on forward side of PET substrate. For the laser beam incidence on reverse side, the laser beam is expected to be transferred and scattered through the PET substrate and the laser beam energy is thought to be dependent on the etch laser pulse beam energy.
Ferroelectric Pb(Zr0.52Ti0.48)O₃ (PZT) films were deposited on SrTiO₃(100) substrate by using conductive SrRuO₃ films as underlayer and their structural and ferroelectric properties were investigated. PZT films were grown in (00l) orientation on well lattice-matched pseudo-cubic SrRuO₃ films. Thickness dependence of ferroelectric and electrical properties of PZT films was investigated. PZT film with 400 nm thickness showed a remanent polarization (Pr) of 29.0 μC/cm² and coercive field (Ec) of 83 kV/cm, and Pr decreased and Ec increased with thickness reduction. The dielectric constant for PZT films showed gradual decrease with thickness reduction. Breakdown field of PZT films did not show the thickness dependence and displayed as high value as 1 MV/cm.
Single-layered transition metal dichalcogenides (TMDs) exhibit more interesting physical properties than those of bulk TMDs owing to the indirect to direct bandgap transition occurring due to quantum confinement. In this research, we demonstrate that layer-by-layer laser etching of molybdenum diselenide (MoSe2) flakes could be controlled by varying the parameters employed in laser irradiation (time, intensity, interval, etc.). We observed a dramatic increase in the photoluminescence (PL) intensity (1.54 eV peak) after etching the samples, indicating that the removal of several layers of (MoSe2) led to a change from indirect to direct bandgap. The laser-etched (MoSe2) exhibited the single (MoSe2) Raman vibration modes at ~239.4 cm-1 and ~295 cm-1, associated to out-of-plane A1g and in-plane E12g Raman modes, respectively. These results indicate that controlling the number of MoSe2 layers by laser etching method could be employed for optimizing the performance of nano-electronic devices.
In this study, the effect of vanadium oxide (V2O5) content and pre-sintering atmosphere on sealing property of glass frit that consisted of V2O5-BaO-ZnO-P2O5-TeO2-CuO-Fe2O3 SeO2 was investigated by XPS (X-ray photoelectron spectroscopy). The content of V2O5 was changed to 15, 30, and 45 mol%, and the pre-sintering was carried out in air and N2 condition, respectively. XPS analysis conducted before and after laser irradiation with identical sample. Before laser treatment, glass frits that were pre-sintered at air condition showed both V4+and V5+, but the valence state was changed to V5+ after laser irradiation when the glass frits contained 30 and 45 mol% V2O5; this change led to non-adhesive property. On the other hand, glass frits that were pre-sintered at N2 condition exhibited only V4+ and it showed fine adhesion irrespective of the V2O5 content. As a result, the existence of V4+ seems to be a major factor for controlling the adhesive property of glass frit for laser sealing.
In this paper, we investigated the electrical properties of crystalline silicon solar cell fabricated with Ni/Cu/Ag plating. The laser process was used to ablate silicon nitride layer as well as to form the selective emitter. Phosphoric acid layer was spin-coated to prevent damage caused by laser and formed selective emitter during laser process. As a result, the contact resistance was decreased by lower sheet resistance in electrode region. Low sheet resistance was obtained by increasing laser current, but efficiency and open circuit voltage were decreased by damage on the wafer surface. KOH treatment was used to remove the laser damage on the silicon surface prior to metalization of the front electrode by Ni/Cu/Ag plating. Ni and Cu were plated for each 4 minutes and 16 minutes and very thin layer of Ag with 1 ㎛ thickness was plated onto Ni/Cu electrode for 30 seconds to prevent oxidation of the electrode. The silicon solar cells with KOH treatment showed the 0.2% improved efficiency compared to those without treatment.
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Performance Prediction of Hybrid Energy Harvesting Devices Using Machine Learning Yoonbeom Park, Kyoungah Cho, Sangsig Kim ACS Applied Materials & Interfaces.2022; 14(9): 11248. CrossRef
In this study, we developed a lead-free P_{2}`O_{5}`-V_{2}O_{5}-ZnO glass frit for sealing OLED using laser irradiation. The frit satisfied the characteristics required for laser sealing such as low glass transition temperature, low coefficient of thermal expansion (CTE), high water-resistance, and high absorption at the wavelength of the laser beam. Ceramic fillers were added to the glass frit in order to further reduce and match its CTE with that of the commercial glass substrate. The addition of Zirconium Tungsten Phosphate (ZWP) to the frit yielded the most desirable results, reducing the CTE to 45.4×10^{-7}/℃, which is very close to that of the glass substrate (44.0×10^{-7}/℃). Successful formation of a solid sealing layer was observed by optical and scanning electron microscopy.
As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different Nd: YVO4 laser beam conditions.
Because the Pb-based piezoelectric materials showed problems such as an environmentalpollution. lead-free ZnSnO3 materials were studied in the present study. The ZnSnO3 thin films weredeposited at 640℃ on Pt/Ti/SiO2 substrate by pulsed laser deposition (PLD) and were annealed for 5 minat 750℃ using rapid thermal annealing (RTA) in nitrogen atmosphere. Samples annealed at 750℃ showeda smooth morphology and an improvement of the dielectric and leakage properties, as compared withas-grown samples. However, electrical properties of the ZnSnO3 thin films obtained in the present studyshould be improved for piezoelectric applications.
Zinc oxide(ZnO) was sputtered on various glass and flexible substrates such as polyethylene terephthalate(PET) and polycarbonate(PC). A Q-switched Nd:YVO4 laser with a wavelength of 1,064 nm was used for the direct etching of ZnO films. It was possible to obtain laser etched line patterns on the ZnO films on PC substrate at some specific laser beam conditions. In the flexible substrates, more thermal energy of laser beam is expected to be spreaded for the etching process.
Fe3O4(magnetite) having half metallic property attracts great attention material with high curie temperature in spintronics. Fe3O4 thin films and nanowires were grown onto c-Al2O3(0001) at various substrate temperatures. Fe3O4 films deposited from 300 to 600℃ are influenced by thermal stress induced from mismatch of thermal expansion coefficient between Fe3O4 and Al2O3 (0001) substrate. The Fe3O4 nanowires grown at 640℃ showed a diameter of 130 nm and a length of 2-10 μm. The nanowire arrays fabricated by pulsed laser deposition technique have high coercivity(Hc) of 608 Oe and Squareness(Mr/Ms) of 0.68 in perpendicular direction.
In this work, we study on the effects of the oxygen pressure on the structural and crystalline of MgZnO thin films. MgZnO thin films were deposited on p-Si (111) substrates by using pulsed laser deposition. The X-ray diffraction analysis and energy dispersive X-ray results revealed that as the oxygen pressure increased and Mg content in the MgZnO films decreased. Also Crystal structure was changed from cubic rock salt to hexagonal wurtzite. Alpha step and atomic force microscopy results showed that the thickness of the films are about 100 nm, and it has been found that the MgZnO (002) preferred orientation were deposited with increasing the oxygen pressure. Therefore, the effect of the preferred orientation, the crystallization grew in the form of the columnar; Grain size and RMS of the films were increased with increasing oxygen pressure.
Laser direct patterning of indium tin oxide(ITO) is one of new methods of direct etching process to replace the conventional photolithography. A diode pumped Q-switched Nd:YVO4 (λ= 1,064 nm) laser was used to produce ITO electrode on various transparent oxide semiconductor films such as zinc oxide(ZnO). The laser direct etched ITO patterns on ZnO were compared with those on glass substrate and were considered in terms of the overlapping rate of laser beam. In case of the laser etching on double-layer, it was possible to obtain the higher overlapping rate of laser beam.
In this study, we have investigated the holographic grating formation on Ag-doped amorphous As-Ge-Se-S thin films. The dependence of diffraction efficiency as afunction of Ag layer thickness has been investigated in this amorphous chalcogenide films. Holographic gratings was formed using [P:P] polarized Diode Pumped Solid State laser (DPSS, 532.0 nm). The diffraction efficiency was obtained by +1st order intensity. The results were shown that the diffraction efficiency of Ag/AsGeSeS double layer thin films for the Ag thickness, the maximum grating diffraction efficiency using 60 nm Ag layer is 0.96%.
We have investigated the sensing properties of ethanol gas sensor with pure ZnO and Ga-doped ZnO nanowires on Au coated (0001) sapphire substrates grown by hot walled pulsed laser deposition. Randomly aligned ZnO nanowires arrays were grown on a Au-electrode patterned under ambient conditions. ZnO nanowires have various sizes and shapes with a different substrate position inside a furnace. The average of length and diameter of the ZnO nanowires were 8 ㎛ and 100 ㎚ respectively, and confirmed by field emission scanning electron microscopy. Sensitivity chanege characterization of the gas sensor was found that measured sensitivities of the ethanol gas sensors were 83.3% and 68.3% at 300℃ respectively.
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