Flash Light Sintering Research Articles

Solution infiltrated lanthanum nickelate–GDC composite cathode via flash-light sintering for intermediate temperature solid oxide fuel cells

Solid oxide fuel cells (SOFCs) require high operating temperatures to minimize the oxygen reduction reaction resistance at cathode and increase the ionic conductivity of oxygen. However, at high operating temperatures, their stability during long-term operation degrades because of material deterioration and the mutual chemical reactions occurring at the interfaces. Herein, an electrode–electrolyte composite is fabricated by solution infiltration of lanthanum nickelate (LNO) electrode material into a GDC electrolyte layer to ensure more reaction sites compared with the conventional powder mixing of the electrode and electrolyte material. Further, the conventional thermal sintering process is replaced with the flash-light sintering process. Thus, the performance of the LNO–GDC cathode cell manufactured by flash-light sintering improves owing to suppression of grain growth of the infiltrated LNO particles. The microstructures of the infiltrated solution and composite layer of the electrolyte material are analyzed using field-emission scanning electron microscopy, and the crystallinity of the LNO nanoparticles is analyzed using high-resolution transmission electron microscopy. A maximum power density of 1.1 W/cm2 is achieved, an improvement of 58 % over the LSCF cell without infiltration at 750 ℃. This study is expected to contribute to the commercialization of SOFCs by replacing conventional thermal sintering.

Coating Robust Layers on Ni-Rich Cathode Active Materials while Suppressing Cation Mixing for All-Solid-State Lithium-Ion Batteries.

This study focused on addressing the challenges associated with the incompatibility between sulfide solid electrolytes and Ni-rich cathode active materials (CAMs) in all-solid-state lithium-ion batteries. To resolve these issues, protective layers have been explored for Ni-rich materials. Lithium lanthanum titanate (LLTO), a perovskite-type material, is recognized for its excellent chemical stability and ionic conductivity, which render it a potential protective layer in CAMs. However, traditional methods of achieving the perovskite structure involve temperatures exceeding 700 °C, resulting in challenges such as LLTO agglomeration, secondary phase formation between LLTO and CAM, and cation mixing within the CAM. In this study, a rapid technique known as flash-light sintering (FLS) was employed to fabricate a uniform and pure perovskite protective layer without inducing cation mixing within the CAM. The LLTO-coated LiNi0.8Co0.1Mn0.1O2 (NCM811) with FLS treatment demonstrated minimal cation mixing and formed a fully covered dense layer. This resulted in a high initial capacity and effectively addressed the incompatibility issues between the sulfide electrolytes and CAM. The rapid FLS method not only streamlines the fabrication of LLTO-coated NCM811 but also provides opportunities for its broader application to materials that were previously deemed impractical because of high sintering temperatures.

Flashlight Sintering Characteristics of the Inkjet-Printed Nanosized Copper Ink on an Auxiliary Heated Paper Substrate

Flashlight Sintering Characteristics of the Inkjet-Printed Nanosized Copper Ink on an Auxiliary Heated Paper Substrate

Lithium-preserved sintering method for perovskite-based solid electrolyte thin films via flash light sintering for all-solid-state lithium-ion batteries

A novel rapid sintering method, namely flash-light sintering, was applied as a post-treatment for spin-coated lithium lanthanum titanate thin films to prevent lithium evaporation and obtain fully dense thin films with perovskite structures.

Flash Light Sintered SOFC Cathode Functional Layer through Electrostatic Spray Deposition

Solid oxide fuel cells(SOFCs), which are attracting attention as an eco-friendly power generation system, are being actively studied due to their fuel flexibility and high efficiency. Since the charge carriers are oxygen ions and have to pass through the solid oxide electrolyte, they require a higher operating temperature (~900 oC) than other fuel cells. To overcome the disadvantages of high-temperature operation, research is being conducted to lower the operating temperature of the SOFCs. In particular, in order to minimize performance degradation even at low operating temperatures, research is being conducted to fabricate cell components as thin films or to apply electrodes with high catalytic activity and large reaction areas.Among the methods of manufacturing thin films, the deposition method using chemical solution deposition(CSD) has the advantage of being cost effective and easily controllable compared to the vacuum deposition method. Electrostatic spray deposition(ESD), one of the CSD deposition methods, is simple to set-up and a variety of compounds can easily be made by controlling the proportions of the precursors. However, a characteristic of the CSD method is that a post heat treatment process is required to obtain desired properties, which consumes a lot of time and cost during the entire process. To solve this problem, processes such as rapid thermal annealing, microwave, and excimer laser ablation are being studied, but these processes have limitations in that they damage the substrate, have a long cooling time, and have a small sintering area. [1, 2] On the other hand, the flash light sintering method using a xenon lamp can perform a post-heat treatment process quickly at room temperature and atmospheric pressure using intense pulsed light, and has the advantage of minimizing damage to the substrate and being applicable to a large area. [3, 4]In this study, the cathode functional layer, which is closely related to the performance of SOFC, was fabricated using the ESD method, and the flash light sintering method was applied for the post-heat treatment process. By applying the flash light sintering method, the heat treatment process, which used to take tens of hours, was shortened to just a few seconds. The sintering behavior of the film produced by flash light sintering was confirmed by comparing the microstructure and crystallinity. In addition, it was confirmed that the film manufactured by flash light sintering worked successfully by comparing the performance with the cell manufactured by the conventional thermal sintering method. Reference [1] R. Bayati et al., "Modification of Properties of Yttria Stabilized Zirconia Epitaxial Thin Films by Excimer Laser Annealing," (in English), Acs Applied Materials & Interfaces, vol. 6, no. 24, pp. 22316-22325, Dec 24 2014.[2] H. S. Hao, L. H. Xu, Y. Huang, X. M. Zhang, and Z. P. Xie, "Kinetics mechanism of microwave sintering in ceramic materials," (in English), Science in China Series E-Technological Sciences, vol. 52, no. 9, pp. 2727-2731, Sep 2009.[3] J. S. Park, D. J. Kim, W. H. Chung, Y. Lim, H. S. Kim, and Y. B. Kim, "Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films," (in English), Scientific Reports, vol. 7, Sep 29 2017.[4] J. S. Park, H. Lee, S. Heo, and Y. B. Kim, "Heater-assisted intense pulsed light irradiation for lanthanum strontium cobaltite thin film electrode fabrication," (in English), Thin Solid Films, vol. 697, Mar 1 2020.

Fabrication of Nano Samarium Doped Ceria(SDC) Infiltrated La6Sr4Co2Fe8O3-δ(LSCF) Composite Cathode for High Performance It-SOFCs

The solid oxide fuel cells(SOFCs) use oxygen ions generated by an oxygen reduction reaction(ORR) supplied to the cathode as charge carrier. Oxygen ions transferring across the solid oxide electrolyte via a hoping mechanism require a high operating temperature to overcome the low ionic conductivity. High ionic conductivity and performance can be obtained at high operating temperature, but the stability is reduced during operation condition due to deterioration of component materials and mutual chemical reactions at the interface. For this reason, researches have proceeded to lower operating temperature of to the intermediate temperature regime(650~750℃) and to develop the electrode layers having high performance at the lower operating temperature. However, since the oxygen reduction reaction resistance is increased, the performance of the SOFCs is reduced at the lower operating temperature. Therefore, many research institutes of fuel cells have added the composite cathode functional layer(CFL) to improve the fuel cell performance between electrolyte and electrode layers using various methods, composite powder, and infiltration. [1, 2] In this study, the solid oxide fuel unit cells are fabricated having the electrolyte/electrode composite layer which was applied to the LSCF electrode infiltrated with nanoparticle SDC for obtaining the many reaction site compared with conventional powder composite materials. When the LSCF-SDC composite cathode functional layer is manufactured, it is applied that the novel flash light sintering method replace the conventional thermal sintering method. Since it can finish the manufacturing process in seconds, the LSCF-SDC cathode layer has the LSCF cathode with nanoparticle SDC suppressed grain growth of the particles which can contribute to improving the performance of the fuel cells.[3] The microstructure of the infiltrated solution and the composite layer of the electrolyte material is analyzed using scanning electron microscopy (FE-SEM) and transmission electron microscopes energy dispersive spectroscopy (TEM-EDS). The crystallinity of nanoparticle SDC is analyzed using FR-TEM and X-ray diffraction. And, the electrochemical analysis of LSCF-SDC cathode cell is carried out at 650~750°C. The performance improvement of the solid oxide fuel cell at intermediate operating temperature is maximized through the fabrication of the cathode functional layer using the solution infiltration method and the alternative flash light sintering process. Reference [1] J. Hong, A. Bhardwaj, Y. Namgung, H. Bae, S.-J. Song, Evaluation of the effects of nanocatalyst infiltration on the SOFC performance and electrode reaction kinetics using the transmission line model, Journal of Materials Chemistry A, 8 (2020) 23473-23487.[2] J. Shin, S. Yang, H.-I. Ji, S. Park, H. Kim, J.-W. Son, J.-H. Lee, B.-K. Kim, J. Hong, K.J. Yoon, Low-temperature processing technique of Ruddlesden-Popper cathode for high-performance solid oxide fuel cells, Journal of Alloys and Compounds, 868 (2021) 159092.[3] Y. Lim, J. Park, H. Lee, M. Ku, Y.-B. Kim, Rapid fabrication of lanthanum strontium cobalt ferrite (LSCF) with suppression of LSCF/YSZ chemical side reaction via flash light sintering for SOFCs, Nano Energy, 90 (2021) 106524.

(Invited) A Novel, Ultra-Fast Fabrication of SOFCs By Flash Light Sintering Process

Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems because of their high energy conversion efficiency, fuel flexibility and low emission of pollutant. In the last decades, the SOFC technology has rapid progress in terms of performance and durability aspect, expanding its application ranges from stationary system to portable devices. In the fabrication of SOFCs, a simple and mass productive fabrication process such as screen-printing, tape casting and sol-gel method are widely used in the industry because it is easy, scalable and economical process. However, a high temperature post heat-treatment process is required to ensure material properties of the ceramic electrolyte and electrode in these processes. In particular, to achieve a highly dense electrolyte layer, a high sintering temperature above 1300oC is usually employed in the fabrication process, which causes considerable amount of time and significant manufacturing costs. Therefore, reducing the sintering temperature and long process time is one of the major challenges to reduce the fabrication cost and facilitate the commercialization of SOFCs. To overcome this problem, many efforts have been made to demonstrate alternative sintering process to reduce the sintering temperature and process time. For example, several researchers proposed spark plasma sintering process as an alternative sintering process because of the high heating rate within a short time based on Joule heating mechanism [1, 2]. However this process has a limitation of complex vacuum system configuration and high equipment cost for commercialization. In addition, excimer laser ablation annealing and microwave sintering process have been also suggested but there are still limitations such as extremely narrow spot size and complexity of microwave interactions with materials respectively [3, 4]. On the other hand, the flash light sintering process presented here uses a white flash light generated by a xenon arc lamp discharge as a heat treatment sources and has many advantages of an extremely short process time, scalability and simple process condition as standard ambient and temperature. Most of all, because this process conducted within a few seconds, it can significantly improve the productivity and cost-effectiveness of the SOFCs. Our previous works successfully demonstrated that the solution-based YSZ thin films was annealed by flash light sintering and it showed comparable material properties to the conventional thermal sintering process [5]. Nevertheless, due to the low light absorption property and difficulty to sinter the ceramic particles, studies on the flash light sintering process for the powder-based films are still limited. In this work, we demonstrate for the first time rapid fabrication of SOFCs using a novel flash light sintering process. The ceramic electrolyte and electrode was fabricated by using mass productive screen-printing method and flash light sintering process was employed as an alternative sintering process of conventional thermal sintering method. In the sintering process, the effect of various pulse conditions on the sinterbility of the ceramic components were investigated, and the material properties such as microstructure, crystallinity and electrochemical property were analyzed. The optimized ceramic components were employed to fabricate SOFC unit cell and their cell performance and impedance behavior was evaluated to demonstrate the flash light sintering process. Reference [1] Deepash Shekhar Saini et al. “Improved conductivity of spark plasma sintered Ho-Substituted Ba-ZrO3 electrolyte ceramics for IT-SOFCs.” ACS Applied Energy Materials. 1, 7, 3469-3478 (2018)[2] Tatiana L. Simonenko et al. “Spark plasma sintering of nanopowders in the CeO2-Y2O3 system as a promising approach to the creation of nanocrystalline intermediate-temperature solid electrolytes.” Ceramics International, 44, 16, 19879-19884 (2018)[3] Hao, H., Xu, L., Huang, Y., Zhang, X. & Xie, Z. “Kinetics mechanism of microwave sintering in ceramic materials.” Science in China Series E: Technological Sciences 52, 2727–2731 (2009).[4] Bayati, R. et al. “Modifcation of properties of yttria stabilized zirconia epitaxial thin flms by excimer laser annealing.” ACS applied materials & interfaces 6, 22316–22325 (2014).[5] Park, J.S. et al. Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films. Scientific reports 7, 12458 (2017)

Ultrafast flashlight sintered mesoporous NiO nanosheets for stable asymmetric supercapacitors

Ultrafast flashlight sintering (FLS) has become an important green manufacturing technology for the structural reformation of various nanomaterials. Nickel oxide (NiO) has been extensively studied as a promising electrode material for electrochemical energy storage owing to its high theoretical specific capacitance, low cost, and appropriate chemical compatibility. This study reports the fabrication of mesoporous ultrathin NiO nanosheets on carbon cloth (CC) as green electrodes for flexible supercapacitors (SCs) through an exceptional ultrafast millisecond FLS process at room temperature. The optimized FLS-NiO@i12J electrode exhibited a remarkable specific capacity of 202.3 mA h g−1 (1215 F g−1) at a current density of 2 A g−1. Strikingly, the as-fabricated FLS-NiO electrodes outperformed the time and energy-consuming conventional thermally annealed (CTA) NiO electrodes. Furthermore, the flexible FLS-NiO@i12J//rGO asymmetric SCs deliver a remarkable energy density of 47.18 Wh kg−1 at a power density of 758.37 W Kg−1 and extraordinary cycling stability performance after 15,000 cycles. In addition, the FLS-NiO@i12J electrodes offer unique mesoporous structures, high surface areas, and numerous open-pore channels of ultrathin NiO nanosheets that facilitate fast transport of ions and rapid redox reactions. Thus, the present approach is promising for designing advanced electrode materials for flexible energy storage applications.

ESB 소결 조제를 이용한 고체산화물 연료전지용 YSZ 전해질의 초고속 광소결 공정에 관한 연구

A high temperature sintering process for solid electrolyte is the main cause of the increase in manufacturing costs of SOFCs. In this study, we developed a novel flash light sintering technique as an alternative sintering process of the conventional thermal sintering process. The YSZ electrolyte films were fabricated by conventional screen-printing method and the flash light sintering process and ESB sintering aid were applied to improve the flash light sinterability of the YSZ electrolyte. In the flash light sintering process, the effect of various pulse conditions such as energy density, and pulse interval were investigated and the microstructure, crystallinity, and sintering behavior of the sintered films were analyzed to demonstrate the effectiveness of the flash light sintering process. The flash light sintered YSZ electrolyte layer was used to fabricate the anode-supported SOFCs and its functionality is successfully demonstrated with the high open circuit voltage. The significance of this study includes minimization of the process time from tens of hours to just a few seconds, thus facilitating the commercialization of SOFCs.

Flash Light Sintered Lanthanum Strontium Cobalt Ferrite(LSCF) Electrode for High Performance IT-SOFCs

The high temperature(900oC~) thermal sintering process is necessary to fabricate the Solid oxide fuel cells(SOFCs). However, the chemical reaction has occurred between solid oxide material components, electrode and electrolyte. In the case of lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-δ, LSCF) electrode, the SrZrO3(SZO) secondary phase is produced at the electrolyte interface even when using the gadolinium doped ceria(GDC) buffer layer for blocking the strontium and zirconium diffusion. The SZO layer hinders the oxygen ion transfer and deteriorates fuel cell performance. By using a novel flash light sintering(FLS) method, we have successfully solved the problem of secondary phase formation in the conventional high temperature thermal sintering process. The microstructure and thickness of the LSCF electrode are analyzed using a field emission scanning electron microscope(FE-SEM). The strontium diffusion and secondary phase are confirmed by X-ray diffraction (XRD), energy dispersive spectrometer method of SEM, TEM (SEM-, TEM-EDS). The NiO-YSZ anode supported LSCF cathode cells are adopted for electro chemical analysis which is measured at 750oC. The maximum power density of the thermal sintered LSCF cathode at 1050oC is 699.6mW/cm2, while that of the flash light sintered LSCF cathode is 711.6mW/cm2. This result proves that the electrode was successfully sintered without a secondary phase using flash light sintering.

Sub-second sintering process for La6Sr4Co2Fe8O3-δ-gadolinium doped ceria composite cathode via a flash light irradiation method for intermediate temperature-solid oxide fuel cells

A solid oxide fuel cell (SOFC) requires an elevated operating temperature to achieve high oxygen ion conductivity and the oxygen reduction reaction (ORR). However, at high operating temperatures above 800 °C, performance deteriorates due to the chemical reaction of the electrode and electrolyte materials at the interface. Therefore, it is necessary to lower the operating temperature to the intermediate temperature regime while maintaining the high oxygen reduction reaction kinetics. One approach is adopting the composite cathode material such as La6Sr4Co2Fe8O3-δ-gadolinium doped ceria (LSCF-GDC). However, the high temperature in the fabrication process results in non-conduction material of strontium zirconate (SrZrO3, SZO) layers at the cathode/electrolyte interface, which blocks oxygen ion conduction and degrades the fuel cell performance. By utilizing the novel flash light sintering process, which can be completed in a few seconds, high temperature fabrication issues are solved. The surface microstructure and thickness of the composite electrode are inspected using a scanning electron microscope (FE-SEM). The secondary phase generation and chemical reaction are analyzed using XRD (X-ray diffraction), SEM-EDS, and TEM-EDS. The anode supported LSCF-GDC cathode cells are measured from 600 °C to 750 °C. The maximum power density at 750 °C of the novel flash light sintered LSCF-GDC composite cathode cell is 727.4 mW/cm2. In addition to the utilization of high performing cathode structure, the flash light sintering process dramatically reduces the process time and suppresses the side reaction at the cathode/electrolyte interface.

Rapid fabrication of lanthanum strontium cobalt ferrite (LSCF) with suppression of LSCF/YSZ chemical side reaction via flash light sintering for SOFCs

The chemical side reaction between a lanthanum strontium cobalt ferrite (LSCF) cathode and an yttria-stabilized zirconia (YSZ) electrolyte is a key problem for solid oxide fuel cell (SOFC) fabrication. Herein, we demonstrate rapid fabrication of an LSCF cathode using a novel flash light sintering (FLS) technique to suppress the chemical side reaction; notably, no Gd-doped ceria interlayer is required. The FLS-fabricated LSCF cathode shows comparable crystalline development and microstructural evolution to a cathode fabricated using the conventional high-temperature sintering process. A clear LSCF/YSZ interface appears, indicating suppression of detrimental chemical side reactions via rapid and surface-dominant sintering kinetics. Detailed interfacial microstructure analysis reveals the absence of Sr segregation and SrZrO3 formation at the FLS-LSCF cathode/YSZ electrolyte interface. Remarkable performance of 0.9 W cm–2 power density at 750 °C is achieved for a cell incorporating the rapidly fabricated LSCF cathode on the interlayer-free YSZ electrolyte owing to suppression of the insulating secondary phases and significantly reduced polarization resistance. Hence, rapid LSCF cathode fabrication via the novel FLS method effectively suppresses secondary phase formation at the LSCF/YSZ interface and greatly simplifies SOFC fabrication by eliminating the doped-ceria-based interlayer. Moreover, this novel method could help overcome interfacial chemical reaction problems in various solid-state devices, while also providing new application opportunities for high-performance electrolyte/electrode materials.

(Invited) Studies on Fabrication Process Cost Reduction for LT-/IT-SOFCs

Solid oxide fuel cells (SOFCs) have attracted many attentions as a next-generation energy conversion device because of their high efficiency and the ability to use a variety of fuels. However, conventional manufacturing processes cause high manufacturing cost and therefore impedes commercialization of SOFCs. SOFC components are mainly produced by non-vacuum powder based process to improve productivity. To achieve desired material properties high-temperature post-heat treatment process usually above 1400oC is required for a long time for ceramic electrolyte and electrode fabrication. This long and high temperature sintering process significantly increases production costs and becomes a hurdle for widespread usage. Therefore, in order to reduce the manufacturing cost of the SOFCs, it is essential to improve the fabrication process especially the high temperature sintering process. Accordingly, to lower the high sintering temperature, a bilayer sintering process using a sintering aid was designed, and it successfully lower the sintering temperature while maintaining the material properties. The fabricated YSZ electrolyte by the developed low temperature sintering process showed a relatively high performance. In addition, through the applying an innovative flash light sintering process, the rapid sintering process of powder based ceramic electrolyte and electrode are successfully demonstrated for the first time. Therefore, a long process time of several tens of hours in thermal sintering process can be significantly reduced within tens of seconds through the development of flash light sintering process.

Coating 1-Octanethiol-Coated Copper Nano-Ink on a Paper Substrate via Multi-Pulse Flash Light Sintering for Application in Disposable Devices

Inkjet-printed patterns were formed on a paper substrate using anti-oxidant copper nano-ink for application to disposable electronic devices. To prevent substrate damage, the pattern was flash light sintered under ambient conditions using the multi-pulse technique. Pure copper nanoparticles were coated with 1-octanethiol for oxidation resistance using the dry-coating method. Mixing these with 1-octanol solvent at a concentration of 30 wt% produced the copper nano-ink. Photo paper was used as the substrate. The contact angle between the photo paper and copper nano-ink was 37.2° and the optimal energy density for the multi-pulse flash light sintering technique was 15.6 J/cm2. Using this energy density, the optimal conditions were an on-time of 2 ms (duty cycle of 80%) for three pulses. The resistivity of the resulting pattern was 2.8 × 10−7 Ω∙m. After bending 500 times to a radius of curvature of 30 mm, the relative resistance (ΔR/R0) of the multi-pulse flash light-sintered pattern hardly changed compared to that of the unbent pattern, while the single-pulse-sintered pattern showed dramatic increase by 8-fold compared to the unbent pattern. Therefore, the multi-pulse light sintering technique is a promising approach to produce an inkjet-printed pattern that can be applied to disposable electronic devices.

Understanding the role of Nanomorphology on Resistance Evolution in the Hybrid Form-Fuse Process for Conformal Electronics

Manufacturing conformal electrically conductive circuits on rigid freeform surfaces currently require compromises between process scalability, cost, and thermal tolerance and geometric complexity of the object material. The Form-Fuse process operates by printing silver nanoparticle interconnects on planar polymer sheets followed by sequential vacuum forming and Flash Light Sintering (FLS) and can overcome the above issues. We investigate the role of nanoparticle morphology on this process by using nanowires (NW) in combination with nanoflakes (NF) and nanospheres (NS) as the printed nanoparticles. The characterization of FLS temperature, electrical resistance, morphology, and optical absorption along with electromagnetic and molecular dynamics modeling yields the following insights. The forming-induced resistivity rise is greater for higher NS and NF content due to localized embedding of NWs into the polymer. This embedding also reduces blowoff defects during FLS to create an expanded defect-free FLS window. The resistance reduction due to FLS is also greater for the mixed NW-NF and NW-NS cases, thanks to the change in localized optical absorption and interparticle fusion kinetics upon the introduction of NFs and NSs into a NW ensemble. The change in fusion kinetics is driven by enhanced dislocation growth between nanoparticles, despite surface and grain boundary diffusion trends contrary to the neck growth trends. We show that Form-Fuse can achieve similar or lesser electrical resistivity than state-of-the-art conformal 3D printing while enabling greater scalability and structural material capability and retaining the capability to handle complex shapes. We discuss the impact of our findings on the nanoparticle material cost and capabilities of Form-Fuse compared to other conformal electronics manufacturing processes.

Highly transparent and conductive electrodes enabled by scalable printing-and-sintering of silver nanowires

Silver nanowires (Ag NWs) have good promised for flexible and transparent electronics. However, It remains an open question on how to achieve large-scale printing of Ag NWs with high optical transparency, electrical conductivity, and mechanical durability for practical applications, though extensive research has been conducted for more than a decade. In this work, we propose a possible solution that integrates screen printing of Ag NWs with flash-light sintering (FLS). We demonstrate that the use of low-concentration, screen-printable Ag NW ink enables large-area and high-resolution patterning of Ag NWs. A critical advantage comes from the FLS process that allows low-temperature processing, short operational time, and high output rate—characteristics that fit the scalable manufacturing. Importantly, we show that the resultant Ag NW patterns feature low sheet resistance (1.1–9.2 Ohm sq−1), high transparency (75.2–92.6%), and thus a remarkable figure of merit comparable to state of the art. These outstanding properties of Ag NW patterns, together with the scalable fabrication method we propose, would facilitate many Ag NW-based applications, such as transparent heaters, stretchable displays, and wearable devices; here, we demonstrate the novel design of flexible and transparent radio frequency 5G antennas.

Effect of Flash Light Sintering on Silver Nanowire Electrode Networks.

We investigated the flash light sintering process to effectively reduce electrical resistance in silver nanowire networks. The optimum condition of the flash light sintering process reduces the electrical resistance by ~20%, while the effect of the conventional thermal annealing processes is rather limited for silver nanowire networks. After flash light sintering, the morphology of the junction between the silver nanowires changes to a mixed-phase structure of the two individual nanowires. This facile and fast process for silver nanowire welding could be highly advantageous to the mass production of silver nanowire networks.

Effect of Nanomaterial Shape on Fabrication of Conformal Circuits

This paper investigates how the change in nanomaterial (NM) shape influences resistance evolution during conformal interconnect fabrication via sequential Vacuum-forming and Flash Light Sintering (FLS) approach. The NM shape in the conformal circuit is tuned by mixing nanowires (NW) with nanoflakes (NF) or nanospheres (NS) at different mixing ratios. The change in line resistance post-forming and post-sintering for any given mixing ratio is studied in greater depth using SEM characterization, UV-Vis spectrophotometry and thermal measurements. For optimal NM mixing ratio and process parameters, the fabricated circuit achieves electrical resistivity of 55.4 µΩ-cm within 30 seconds on a wall inclined at 60⁰ to the horizontal with a width to height aspect ratio of 2.5:1.

Ultra-fast fabrication of lanthanum strontium manganese thin films using intense pulsed light irradiation

Commercialization of thin film manufacturing is limited due to the long process time and fabrication cost. To solve these problems, the intense pulsed light sintering method was proposed in this paper. This novel sintering process using xenon lamp irradiation accomplished sintering in milliseconds in ambient air. For evaluation of the sintering effects, wide ranges of irradiation energy densities and substrate temperatures were investigated. The additional thermal energy from bottom-heating results in reducing the required photonic energy density. A flash light sintering process was applied to fabricate a lanthanum strontium manganese (La0.8Sr0.2Mn1O3-δ) perovskite structure used in energy and memory devices. The La0.8Sr0.2Mn1O3-δ thin film was coated by an electrostatic spray deposition (ESD) technique, using chemical deposition. This ESD technique is suitable for the flash light sintering process because a wet chemical method facilitates rapid and low-cost commercial fabrication. After the LSMO thin films were coated, the conventional thermal and flash light sintering processes were conducted, and the properties of the LSMO thin film were evaluated for remnant organics, electrical conductivity, crystallinity, and surface morphology. Flash light sintering delivers a complete sintering process in under 1 s, eliminating the frequent obstacles inherent in thermal sintering.

Rapid Fabrication of Chemical Solution-Deposited Lanthanum Nickelate Thin Films via Intense Pulsed-Light Process

In this paper, we demonstrate the practicality and feasibility of the flash light-sintering method to fabricate the ceramic material perovskite structure for lanthanum nickel oxide (LaNiO3; LNO) thin films using flash light irradiation equipment. LNO thin films are deposited on an Si wafer and Al2O3 substrate via the chemical solution deposition (CSD) method and sintered by a thermal and flash light-irradiation process with a bottom heater. The properties of flash light-sintered LNO thin films are compared with those of thermally sintered films. The surface morphology, crystal development, and electric conductivity of the LNO thin films are measured by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and a four-point probe, respectively. Flash light sintering was accomplished in milliseconds. Through the comparison of thermal sintering and flash light-sintering results, it was confirmed that perovskite LNO thin films deposited by the CSD method can be fabricated by flash light sintering. We show that the flash light sintering method can solve several inherent issues of the conventional thermal sintering method.