Organic solar cells using plasmonics of Ag nanoprisms

We demonstrate plasmonic effects in bulk heterojunction organic solar cells (OSCs) consisting of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) by incorporating silver (Ag) triangular shaped nanoparticles (nanoprisms; NPSs) into a poly(3,4-ethylenedioxythiophene) buffer layer. The optical absorption and geometric characteristics of the Ag NPSs were investigated in terms of their tunable in-plane dipole local surface plasmon resonance (LSPR) bands. The photovoltaic characteristics showed that the power conversion efficiency (PCE) of the plasmonic OSCs was enhanced by an increase of short circuit current (J_sc) compared to that of the reference cells without any variation in electrical properties. The enhanced J_sc is directly related to the enhancement of optical absorption efficiency by the LSPR of the Ag NPSs. We measured the photovoltaic characteristics of the plasmonic OSCs with various distances between the Ag NPSs and the P3HT:PCBM active layer, in which the PCEs of the plasmonic OSCs decreased with increasing distance. This suggests that the increase of photocurrent and optical absorption was due to near field enhancement (i.e., intensified incident light on the active layer) by the LSPR of the Ag NPSs.     

Printed,Flexible, Organic Nano‐Floating‐Gate Memory: Effects of Metal Nanoparticles and Blocking Dielectrics on Memory Characteristics

The effects of using a blocking dielectric layer and metal nanoparticles (NPs) as charge‐trapping sites on the characteristics of organic nano‐floating‐gate memory (NFGM) devices are investigated. High‐performance NFGM devices are fabricated using the n‐type polymer semiconductor, poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (P(NDI2OD‐T2)), and various metal NPs. These NPs are embedded within bilayers of various polymer dielectrics (polystyrene (PS)/poly(4‐vinyl phenol) (PVP) and PS/poly(methyl methacrylate) (PMMA)). The P(NDI2OD‐T2) organic field‐effect transistor (OFET)‐based NFGM devices exhibit high electron mobilities (0.4–0.5 cm² V^?1 s^?1) and reliable non‐volatile memory characteristics, which include a wide memory window (≈52 V), a high on/off‐current ratio (I_on/I_off ≈ 10⁵), and a long extrapolated retention time (>10⁷ s), depending on the choice of the blocking dielectric (PVP or PMMA) and the metal (Au, Ag, Cu, or Al) NPs. The best memory characteristics are achieved in the ones fabricated using PMMA and Au or Ag NPs. The NFGM devices with PMMA and spatially well‐distributed Cu NPs show quasi‐permanent retention characteristics. An inkjet‐printed flexible P(NDI2OD‐T2) 256‐bit transistor memory array (16 × 16 transistors) with Au‐NPs on a polyethylene naphthalate substrate is also fabricated. These memory devices in array exhibit a high I_on/I_off (≈10^{4 ± 0.85}), wide memory window (≈43.5 V ± 8.3 V), and a high degree of reliability.     

Multiwavelength switchable SOA-fibre ring laser using digital micromirrors

A novel multiwavelength switchable SOA-fibre ring laser incorporating digital micromirrors is demonstrated. By controlling the states of micromirrors, the flexible allocation of the wavelength channels and the multiwavelength switching operations is achieved. Up to 12 wavelength channels with 0.8 nm spacing at room temperature are generated.     

Effect of surface finish material on printed circuit board for electrochemical migration

This study investigates whether the electrochemical migration (ECM) is affected by factors such as the printed circuit board (PCB) surface finish, distance between the electrodes and bias voltage under water drop (WD) and polarization tests. The main element of the dendrite structure for ENIG (electroless nickel and immersion gold), electroless Ag and electroplate Sn was nickel, silver and tin, respectively. The order of speed in which the dendrite structure was formed from the cathode electrode to the anode electrode on the PCB with various surface finishes was electroless Ag, electroplate Sn and ENIG, irrespective of the distance between the electrodes and the bias voltage. The ECM rate was increased by decreasing the distance between conductors of the opposite polarity and increasing the bias voltage. The order of corrosion rate in distilled water with pH 6.5 and NaCl 1.0 wt% solution was electroless Ag, electroplate Sn and ENIG. This trend was corresponded with the tendency for ECM rate.     

Laser-Induced Surface Reconstruction of Nanoporous Au-Modified TiO2 Nanowires for In Situ Performance Enhancement in Desorption and Ionization Mass Spectrometry

The physicochemical properties of nanostructured substrates significantly impact laser desorption/ionization mass spectrometry (LDI-MS) performance. Fundamental understanding of the substrate properties can provide insights into the design and development of an efficient LDI matrix. Herein, a hybrid matrix of nanoporous Au-modified TiO₂ nanowires (npAu-TNW) is developed to achieve enhanced LDI-MS performance. Its origin is investigated based on hybrid matrix properties including photo–thermal conversion and electronic band structure. Notably, further improvement is obtained in the npAu-TNW than in the pristine TNW and non-porous Au nanoisland-modified TNW (Au-TNW) hybrid, which is attributed to the laser-induced surface restructuring/melting phenomenon. Noticeable surface restructuring/melting occurs in the npAu by laser exposure through efficient photo–thermal conversion of the highly porous npAu. At this instant of npAu structural changes, internal energy transfer from the npAu to the adsorbed analyte is promoted, which facilitates desorption. Moreover, strain is developed in situ in the TNW adjacent to the restructuring npAu, which distorts the TNW lattice. The strain development reduces recombination rates of charge carriers by introducing shallow trap levels in the bandgap, which enhances the ionization process. Ultimately, the high LDI-MS performance based on the npAu-TNW hybrid matrix is demonstrated by analyzing neurotransmitter.     

Model of Knowledge-Based Process Management System Using Big Data in the Wireless Communication Environment

For any small and medium-sized manufacturer, delivery deadline compliance and quality assurance are the most important factors for their survival. And, for the compliance to delivery deadline, the SCM system that integrates the manufacturing process covering from the material purchase to the product release and the demand process covering from the logistics to the sales process is required. To guarantee the manufacturing quality, a system that maintains the optimized rate-of-production by responding in advance to any fault occurrence in the process and/or the facility is required. The big data analysis technology that is required to provide the decision support system optimized for the analysis based manufacturing management for small and medium-sized manufacturers greatly in need for their survival and competition has been introduced. This study aims to develop a model of knowledge-based system for manufacturing facilities optimization specialized for small and medium-sized manufacturers by collecting and analyzing data generated in the supply chain networks and manufacturing facilities of small and medium-sized manufacturers. This study proposes the development of knowledge-based process management system for the survival and the competitiveness improvement for small and medium-sized manufacturers in very weak business conditions. Specifically, the proposal is on the development of system and its service model to support the decision on the manufacturing process management by providing high level knowledge through the data analysis on manufacturing facilities of small and medium-sized manufacturers.     

An intelligent power amplifier MMIC using a new adaptive bias control circuit for W-CDMA applications

A high-linearity and high-efficiency MMIC power amplifier is proposed that adopts a new on-chip adaptive bias control circuit, which simultaneously improves efficiency at the low output power level and linearity at the high output power level. The adaptive bias control circuit detects the input power level and supplies a low quiescent current of 16 mA at the low output power level and an increased current up to 90 mA according to the increased power level adaptively. The intelligent W-CDMA power amplifier using the adaptive bias circuit exhibits an improvement of average power usage efficiency of more than 1.93 times, and an adjacent channel leakage ratio by 4 dB at the output power of 28.3 dBm.     

Novel Clock Phase Offset and Skew Estimation Using Two-Way Timing Message Exchanges for Wireless Sensor Networks

Recently, a few efficient timing synchronization protocols for wireless sensor networks (WSNs) have been proposed with the goal of maximizing the accuracy and minimizing the power utilization. This paper proposes novel clock skew estimators assuming different delay environments to achieve energy-efficient network-wide synchronization for WSNs. The proposed clock skew correction mechanism significantly increases the re-synchronization period, which is a critical factor in reducing the overall power consumption. The proposed synchronization scheme can be applied to the conventional protocols without additional overheads. Moreover, this paper derives the Cramer-Rao lower bounds and the maximum likelihood estimators under different delay models and assumptions. These analytical metrics serves as good benchmarks for the thus far reported experimental results     

A Large Bandgap Organic Salt Dopant for Sn-Based Perovskite Thin-Film Transistor

Metal halide perovskite optoelectronic devices have made significant progress over the past few years, but precise control of charge carrier density through doping is essential for optimizing these devices. In this study, the potential of using an organic salt, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, as a dopant for Sn-based perovskite devices, is explored. Under optimized conditions, the thin film transistors based on the doped 2D/3D perovskite PEAFASnI₃ demonstrate remarkable improvement in hole mobility, reaching 7.45 cm²V⁻¹s⁻¹ with a low subthreshold swing and the smallest sweep hysteresis (ΔV_hysteresis = 2.27 V) and exceptional bias stability with the lowest contact resistance (2.2 kΩ cm). The bulky chemical structure of the dopant prevents it from penetrating the perovskite lattice and also surface passivation against Sn oxidation due to its hydrophobic nature surface. This improvement is attributed to the bifunctional effect of the dopant, which simultaneously passivates defects and improves crystal orientation. These findings provide new insights into potential molecular dopants that can be used in metal halide perovskite devices.     

Improved channel assignment scheme with access control for thecommon packet channel in WCDMA systems

We propose a channel assignment scheme with access control for obtaining better system performance within the common packet channel (CPCH) access procedure of wideband code-division multiple-access (WCDMA) systems. The proposed scheme is analyzed taking multiple access interference into consideration and is compared with other schemes in the 3rd Generation Partnership Project (3GPP): the basic scheme, the channel monitoring scheme, and the channel assignment scheme without access control. The results show that the proposed scheme provides high throughput, even under high-loading conditions, since the access control algorithm based on channel load prohibits excessive interference