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Technology for monitoring the concentration of high-concentration hydrogen gas, which is used as a fuel for hydrogen fuel cell vehicles, is urgently needed to be developed to maximize vehicle fuel efficiency. To improve the detection performance of the proton conductor-based hydrogen sensor, a membrane electrode assembly (MEA) consisting of a Nafion membrane and a Pt-C composite electrode was manufactured and applied to the hydrogen sensor. The hot press method was used to manufacture the MEA, and the junction characteristics were optimized by changing pressure, temperature, and time. The MEA was manufactured at a pressure range of 2–5 MPa, a temperature range of 40–80 °C, and a time range of 60–120 s, and the sheet resistance of the MEA was measured to investigate its dependence on the bonding process conditions. When the electrode-Nafion junction temperature and pressure were high, the MEA was stuck to the substrate or paper sheet and could not be separated into a discrete MEA. Additionally, when the temperature was low, the junction strength was insufficient, causing the Nafion and electrode to separate from each other. Through this study, it was confirmed that a robust and conductive MEA was obtained under optimal bonding conditions of 2 MPa, 60 °C, and 60 s, and the sensitivity of the hydrogen sensor was significantly improved. [ABSTRACT FROM AUTHOR]

In this study, we introduce the world's first development of a full‐color micro‐LED display utilizing a Simultaneous Transfer and Bonding (SITRAB) process and a novel SITRAB film. Developed micro‐LED display involves R/G/B micro‐LED chips measuring 35 × 20 µm 2, arranged into a display resolution of 32 × 32, with a pixel pitch of 324 µm and a subpixel pitch of 50 µm. The micro‐LED display utilizes a glass substrate and aluminum wiring. A key innovation in our process is the use of indium solder for low‐temperature bonding, significantly enhancing the assembly process's efficiency and reliability. The SITRAB film, a specially developed material by ourselves, removes the surface oxide of indium solders, facilitating effective bonding between the micro‐LEDs and the display electrodes. Post‐curing of this SITRAB film further enhances the shear strength of the micro‐LEDs. An average shear strength of approximately 5.45 gf (about 32 MPa), significantly surpassing the tensile strength of indium. These advancements not only demonstrate the feasibility of the SITRAB process and the new film material in creating high‐quality micro‐LED displays but also significantly boost the reliability of these displays. [ABSTRACT FROM AUTHOR]

Micro light‐emitting diodes (µLEDs) have been considered as next‐generation display technologies, but they suffer from low productivity due to poor heat dissipation, high electrical resistance, and repair difficulty of conventional µLED bonding methods. Simultaneous transfer and bonding (SITRAB) technology enables electrically/thermally conductive soldering for high‐resolution µLED displays. In this study, the transfer, bonding, and repair of InGaN/GaN µLEDs via the SITRAB method are reported. µLEDs grown on sapphire substrates are assembled on a backplane via the SITRAB process. The SITRAB‐based repair of defective pixels is demonstrated by transferring redundant LEDs to the display substrates. [ABSTRACT FROM AUTHOR]

The alloying behavior of Li‐alloy‐forming metals in the anode of all‐solid‐state batteries (ASSBs) critically affects the viscoplastic flow and deposition of Li, determining cell performance. Herein, an ultra‐stable breathing Mg anode for Li‐free ASSBs is reported with changes in the inter‐particle distance of the Mg particles during operation. It is proposed that this unique Li deposition between Mg particles is derived from the Li concentration gradient (LCG) from the surface to the core of the Mg particle, creating a driving force that attracts Li toward the low‐concentration side and Li accumulation followed by deposition on the Mg surface. Based on a comparative study of Li‐alloy‐forming metals with different alloying and diffusion kinetics, this study ascribes the LCG to the slow alloying kinetics of Mg with Li and slow Li diffusion through the Mg–Li alloys. Interfacial stability is secured by accommodating Li deposits uniformly inside the anode. A full cell with a LiNi0.8Mn0.1Co0.1O2 cathode exhibits ultrahigh stability and reversibility with Coulombic efficiency over 99.9% for 1000 cycles at 30 °C. [ABSTRACT FROM AUTHOR]

This paper presents a study of methods for reducing the erosion of SiO2 in a high-power density (10–40 W/cm3), purely inductive H2/Ar plasma, using a toroidal transformer-coupled plasma source operated at 0.5 Torr. Quartz samples were exposed to plasma densities of 1–3 × 1013 cm−3 and H atom temperatures of 4000–8000 K [electron densities and H translational temperatures were measured by Stark and Doppler broadening of H Balmer-β (Hβ) emission at 486.1 nm]. Laser interferometry was employed to monitor time-resolved temperatures of the quartz substrate. Etching rates were measured by stylus profilometry, and roughness was quantified by atomic force microscopy (AFM). For 5 min discontinuous H2/Ar plasma exposure (0.5 Torr, 16 W/cm3, 1 min plasma-on, 9 min plasma-off per cycle with five cycles), the etching rate during the plasma-on time was 224 nm/min. This was much higher than the 16 nm/min rate observed for a continuous 1 h H2/Ar plasma exposure. This trend was ascribed to the higher substrate temperatures reached with continuous plasma operation and a negative dependence of the etching rate on temperature, described by an activation energy of roughly −5 kcal/mol. When exposure to 1 min H2/Ar plasmas was alternated with 1 min O2/Ar plasma treatments and 12 min plasma-off periods, the etching rate was reduced to near-zero and the extent of surface roughness was reduced by at least fivefold. N2/Ar plasma treatments were less effective in reducing the etching rate (to 57 nm/min), while the roughness to the surface caused by exposure to the H2/Ar 1 min plasmas was nearly eliminated. A mechanism for the erosion process is proposed, involving the penetration of H atoms below the surface where they insert into Si–O–Si linkages to form SiH and SiOH groups. This opening of the SiO2 network allows easier penetration of H, further bond breakage, and crack propagation that eventually leads to the shedding of small silica particles. Periodic exposure to O atoms hydroxalizes these subsurface regions and subsequently reforms Si–O–Si linkages, accompanied by the formation of H2O that presumably diffuses to the surface and desorbs. [ABSTRACT FROM AUTHOR]