Abstract Atom transfer radical polymerization (ATRP) with dual photoredox/copper catalysis combines the advantages of photo-ATRP and photoredox-mediated ATRP, utilizing visible light and ensuring ...broad monomer scope and solvent compatibility while minimizing side reactions. Despite its popularity, challenges include high photocatalyst (PC) loadings (10 to 1000 ppm), requiring additional purification and increasing costs. In this study, we discover a PC that functions at the sub-ppm level for ATRP through mechanism-driven PC design. Through studying polymerization mechanisms, we find that the efficient polymerizations are driven by PCs whose ground state oxidation potential—responsible for PC regeneration—play a more important role than their excited state reducing power, responsible for initiation. This is verified by screening PCs with varying redox potentials and triplet excited state generation capabilities. Based on these findings, we identify a highly efficient PC, 4DCDP-IPN, featuring moderate excited state reducing power and a maximized ground state oxidation potential. Employing this PC at 50 ppb, we synthesize poly(methyl methacrylate) with high conversion, narrow molecular weight distribution, and high chain-end fidelity. This system exhibits oxygen tolerance and supports large-scale reactions under ambient conditions. Our findings, driven by the systematic PC design, offer meaningful insights for controlled radical polymerizations and metallaphotoredox-mediated syntheses beyond ATRP.
Neural interfaces have enabled significant advancements in neuroscience and paved the way for clinical applications in the diagnosis, treatment, and prevention of neurological disorders. A variety of ...device modalities, such as electrical, chemical and optical neural interfacing, are required for the comprehensive monitoring and modulation of neural activity. The development of recent devices with multimodal functionalities has been driven by innovations in materials engineering, especially the utilization of organic soft materials such as polymers, carbon allotropes, and hydrogels. A transition from rigid to soft materials has improved device performance through enhanced biocompatibility and flexibility to realize stable long-term performance. This article provides a comprehensive review of a variety of neural probes ranging from surface-type and implantable electrodes to fiber-based devices. We also highlight the influence of materials on the development of these neural interfaces and their effects on device performance and lifetime.
Abstract
The design-rule shrinkage in semiconductor devices is a challenge at every step of the integration process. In the gap-fill process for isolation, the seam and void formation cannot be ...suppressed by using a deposition process, which even has excellent step coverage. To achieve seamless gap fill in the high-aspect-ratio structure, which has a non-ideal etch profile such as a negative slope, the deposition process should be able to realize the “bottom-up growth” behavior. In this work, the bottom-up growth of a SiO
2
plasma-enhanced atomic layer deposition (PE-ALD) process in a trench structure was investigated by using a growth inhibition process employing plasma treatment. N
2
and NH
3
plasma pre-treatments were employed to suppress the growth of the SiO
2
PE-ALD process without any contamination, and the inhibition mechanism was investigated by performing surface chemistry analyses using X-ray photoelectron spectroscopy. Furthermore, the gap-fill characteristics of the SiO
2
PE-ALD process were examined, depending on the process conditions of NH
3
plasma pre-treatment, by performing cross-sectional field emission scanning electron microscopy measurements. Finally, a seamless gap-fill process in a high-aspect-ratio trench pattern was achieved by the bottom-up growth behavior of SiO
2
PE-ALD using NH
3
plasma pre-treatment.
Limiting the location where electron injection occurs at the cathode interface to a narrower region is the key factor for achieving a highly improved RS performance, which can be achieved by ...including Ru Nanodots. The development of a memory cell structure truly at the nanoscale with such a limiting factor for the electric‐field distribution can solve the non‐uniformity issue of future ReRAM.
Various array types of 1‐diode and 1‐resistor stacked crossbar array (1D1R CA) devices composed of a Schottky diode (SD) (Pt/TiO2/Ti/Pt) and a resistive switching (RS) memory cell (Pt/TiO2/Pt) are ...fabricated and their performances are investigated. The unit cell of the 1D1R CA device shows high RS resistance ratio (≈103 at 1.5 V) between low and high resistance state (LRS and HRS), and high rectification ratio (≈105) between LRS and reverse‐state SD. It also shows a short RS time of <50 ns for SET (resistance transition from HRS to LRS), and ≈600 ns for RESET (resistance transition from LRS to HRS), as well as stable RS endurance and data retention characteristics. It is experimentally confirmed that the selected unit cell in HRS (logically the “off” state) is stably readable when it is surrounded by unselected LRS (logically the “on” state) cells, in an array of up to 32 × 32 cells. The SD, as a highly non‐linear resistor, appropriately controls the conducting path formation during the switching and protects the memory element from the noise during retention.
1 diode 1 resistor (1D1R) resistive memory devices with the crossbar array configuration composed of a stacked Schottky diode (Pt/TiO2/Ti/Pt) and unipolar resistive (URS) memory (Pt/TiO2/Pt) elements are fabricated, and their fluent functionality is proven. Atomic force microscopy is used to image one memory cell and scanning electron microscopy is used to study the 32 × 32 memory array.
In developing an organic light-emitting diode (OLED) panel for a foldable smartphone (specifically, a color filter on encapsulation) aimed at reducing power consumption, the use of a new optically ...clear adhesive (OCA) that blocks UV light was crucial. However, the incorporation of a UV-blocking agent within the OCA presented a challenge, as it restricted the traditional UV-curing methods commonly used in the manufacturing process. Although a visible-light curing technique for producing UV-blocking OCA was proposed, its slow curing speed posed a barrier to commercialization. Our study introduces a highly efficient photo-initiating system (PIS) for the rapid production of UV-blocking OCAs utilizing visible light. We have carefully selected the photocatalyst (PC) to minimize electron and energy transfer to UV-blocking agents and have chosen co-initiators that allow for faster electron transfer and more rapid PC regeneration compared to previously established amine-based co-initiators. This advancement enabled a tenfold increase in the production speed of UV-blocking OCAs, while maintaining their essential protective, transparent, and flexible properties. When applied to OLED devices, this OCA demonstrated UV protection, suggesting its potential for broader application in the safeguarding of various smart devices.
The charge trapping characteristics of the high-k laminated traps with different thickness ratios were investigated in order to improve the distribution of threshold voltage and the charge loss ...problems in 3D NAND flash memories with TCAT structure. In this letter, the interfacial layers are formed between the HfO 2 /Al 2 O 3 laminated films, which increase trap sites and improve charge storage capability. In addition, due to the difference in bandgap between HfO 2 and Al 2 O 3 , the HfO 2 layer forms a deep quantum well and the Al 2 O 3 layer acts as a barrier to prevent the loss of electrons captured in the charge trapping layer. The barriers prevent trapped electrons from escaping to other layers. In other words, it reduces the loss of charges from the charge trapping layer to Si or gate electrode. Also, the number of interfaces and the ratio of appropriate laminate film thickness are important factors for obtaining good data retention characteristics. The experimental results show a higher charge storage density and a larger memory window of 11.5 V in the structure that has many interfaces and a 1/1 of HfO 2 /Al 2 O 3 thickness ratio. In this structure, the leakage current is 4.61<inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 10 −9 A/cm 2 and charge loss rate is 14.9%, which are the lowest values in tested structures. The proposed high-k laminated trap structure may be very useful in future 3D NAND flash memory device applications.
Abstract
A novel nanocomposite-based non-volatile resistance switching random access memory device introducing single-walled carbon nanotube (SWCNT)@TiO
2
core–shell wires was proposed for flexible ...electronics. The SWCNT was de-bundled by ultrasonication with sodium dodecylbenzene sulfonate (SDBS), and then the TiO
2
skin layer on the SWCNT surface was successfully introduced by adding benzyl alcohol as a weak surfactant. The nanocomposite resistance switching layer was composed of the SWCNT@TiO
2
core–shell wires and poly(vinyl alcohol) (PVA) matrix by a simple spin-coating method. The device exhibited reproducible resistance switching performance with a remarkably narrow distribution of operating parameters (V
SET
and V
RESET
were 2.63 ± 0.16 and 0.95 ± 0.11 V, respectively) with a large R
ON
/R
OFF
ratio of 10
5
for 200 consecutive switching cycles. Furthermore, the excellent resistance switching behavior in our device was maintained against mechanical stress up to 10
5
bending test. We believe that the nanocomposite memory device with SWCNT@TiO
2
core–shell wires would be a critical asset to realize practical application for a flexible non-volatile memory field.
Deformable semi-solid liquid metal particles (LMP) have emerged as a promising substitute for rigid conductive fillers due to their excellent electrical properties and stable conductance under ...strain. However, achieving a compact and robust coating of LMP on fibers remains a persistent challenge, mainly due to the incompatibility of conventional coating techniques with LMP. Additionally, the limited durability and absence of initial electrical conductivity of LMP restrict their widespread application. In this study, we propose a solution process that robustly and compactly assembles mechanically durable and initially conductive LMP on fibers. Specifically, we present a shearing-based deposition of polymer-attached LMP followed by additional coating with CNT-attached LMP to create bi-layer LMP composite with exceptional durability, electrical conductivity, stretchability, and biocompatibility on various fibers. The versatility and reliability of this manufacturing strategy for 1D electronics are demonstrated through the development of sewn electrical circuits, smart clothes, stretchable biointerfaced fiber, and multifunctional fiber probes.
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