Enhanced Performance of I2‐Free Solid‐State Dye‐Sensitized Solar Cells with Conductive Polymer up to 6.8%

An iodine‐free solid‐state dye‐sensitized solar cell (ssDSSC) is reported here, with 6.8% energy conversion efficiency—one of the highest yet reported for N719 dye—as a result of enhanced light harvesting from the increased transmittance of an organized mesoporous TiO₂ interfacial layer and the good hole conductivity of the solid‐state‐polymerized material. The organized mesoporous TiO₂ (OM‐TiO₂) interfacial layer is prepared on large‐area substrates by a sol‐gel process, and is confirmed by scanning electron microscopy (SEM) and grazing incidence small‐angle X‐ray scattering (GISAXS). A 550‐nm‐thick OM‐TiO₂ film coated on fluorine‐doped tin oxide (FTO) glass is highly transparent, resulting in transmittance increases of 8 and 4% compared to those of the bare FTO and conventional compact TiO₂ film on FTO, respectively. The high cell performance is achieved through careful control of the electrode/hole transport material (HTM) and nanocrystalline TiO₂/conductive glass interfaces, which affect the interfacial resistance of the cell. Furthermore, the transparent OM‐TiO₂ film, with its high porosity and good connectivity, exhibits improved cell performance due to increased transmittance in the visible light region, decreased interfacial resistance ( Ω ), and enhanced electron lifetime ( τ ). The cell performance also depends on the conductivity of HTMs, which indicates that both highly conductive HTM and the transparent OM‐TiO₂ film interface are crucial for obtaining high‐energy conversion efficiencies in I₂‐free ssDSSCs.     

Reactive Sintering of Copper Nanoparticles Using Intense Pulsed Light for Printed Electronics

Most commercial copper nanoparticles are covered with an oxide shell and cannot be sintered into conducting lines/films by conventional thermal sintering. To address this issue, past efforts have utilized complex reduction schemes and sophisticated chambers to prevent oxidation, thereby rendering the process cost ineffective. To alleviate these problems, we demonstrate a reactive sintering process using intense pulsed light (IPL) in the present study. The IPL process successfully removed the oxide shells of copper nanoparticles, leaving a conductive, pure copper film in a short period of time (2 ms) under ambient conditions. The in situ copper oxide reduction mechanism was studied using several different experiments and analyses. We observed instant copper oxide reduction and sintering through poly(N-vinylpyrrolidone) functionalization of copper nanoparticles, followed by IPL irradiation. This phenomenon may be explained by oxide reduction either via an intermediate acid created by ultraviolet (UV) light irradiation or by hydroxyl (-OH) end groups, which act like long-chain alcohol reductants.     

Impact of node distance on selfish replica allocation in a mobile ad-hoc network

Many data replication techniques have been proposed to minimize performance degradation caused by network partitioning in a mobile ad-hoc network. Most of them assume that all mobile nodes collaborate fully in terms of sharing their memory space. However, in reality, some nodes may selfishly decide to only cooperate partially, or not at all, with other nodes. Recently, a new approach to selfish replica allocation has been proposed to handle node selfishness. However, there is still much room for improvement. We empirically observe that the previous selfish replica allocation strategy suffers from long query delay and poor data accessibility, because it utilizes only non-selfish nodes that may be faraway nodes. In this paper, we propose a novel replica allocation strategy in the presence of selfish nodes, that takes into account both selfish behavior and node distance. Moreover, through a novel node leveling technique, we utilize the memory space of all connected nodes, including selfish nodes. The conducted simulations demonstrate that the proposed strategy outperforms existing replica allocation techniques in terms of data accessibility, query delay, and communication cost.     

Fluorobenzotriazole (FTAZ)‐Based Polymer Donor Enables Organic Solar Cells Exceeding 12% Efficiency

The fluorobenzotriazole (FTAZ)‐based copolymer donors are promising candidates for nonfullerene polymer solar cells (PSCs), but suffer from relatively low photovoltaic performance due to their unsuitable energy levels and unfavorable morphology. Herein, three polymer donors, L24 , L68 , and L810 , based on a chlorinated‐thienyl benzodithiophene (BDT‐2Cl) unit and FTAZ with different branched alkyl side chain, are synthesized. Incorporation of a chlorine (Cl) atom into the BDT unit is found to distinctly optimize the molecular planarity, energy levels, and improve the polymerization activity. Impressively, subtle side chain length of FTAZ realizes a dramatic improvement in all the device parameters, as revealed by the short‐current density (J_sc) improved from 7.41 to 20.76 mA cm^?2, fill‐factor from 36.3 to 73.5%, and even the open‐circuit voltage (V_oc) from 0.495 to 0.790 V. The best power conversion efficiency (PCE) of 12.1% is obtained from the L810‐based device, which is one of the highest values reported for FTAZ‐based PSCs so far. Notably, the corresponding external quantum efficiency curve keeps a very prominent value up to 80% from 500 to 800 nm. The notable performance is discovered from the reduced energy loss, improved molecular face‐on orientation, the down‐shifted energy levels, and optimized absorption coefficient regulated by side‐chain engineering.     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

A moving-actuator type electromechanical total artificial heart.II. Circular type and animal experiment

A new type of electromechanical total artificial heart (TAH) based on circular rolling-cylinder mechanism was developed to overcome critical problems in motor-driven artificial hearts such as large size and difficulties in fitting the heart to atrial remnants and arterial vessels. Its performance and reliability were evaluated in mock circulation and in an animal implant experiment. The total weight and volume of the pump is 650 g and 600 mL, respectively. This new pump was implanted in a calf for total heart replacement and 96 h of survival was achieved. The whole system, including pump, controller, and control algorithm performed well enough to improve the prospect of eventual clinical application of our TAH system.     

Construction of a haptic-enabled broadcasting system based on the MPEG-V standard

With rapid developments in communications technology and digital multimedia, there has been increasing demand in recent years for realistic broadcasting technology beyond conventional audio-visual media. In response to this demand, this paper presents an example of the construction of a haptic-enabled broadcasting system based on the MPEG-V standard that was established recently. The construction processes of the proposed haptic-enabled broadcasting system include various types of media acquisition, haptic content creation by modeling and authoring, transmission, rendering, and interaction. This paper illustrates the data flow within the system, from the creation of haptic contents to the rendering of these contents to the end user, and explains a method of building the system with the MPEG-V standard. The constructed haptic-enabled broadcasting system allows users to have more immersive interaction with the synthesized haptic multimedia, which is closely synchronized with audio-visual data.     

ESPAR array design for the UHF RFID wireless sensor communication system

In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.     

Impedance matching by series condensers for power receivers of in vivo robotic capsules

An impedance matching technique using series condensers for the power receivers of in vivo robotic capsules is proposed. The power delivery function of the condenser ratio and its optimal ratio are derived. Experimental results validate the derived function.     

Regulated Breathing Effect of Silicon Negative Electrode for Dramatically Enhanced Performance of Li‐Ion Battery

Si is an attractive negative electrode material for lithium ion batteries due to its high specific capacity (≈3600 mAh g^–1). However, the huge volume swelling and shrinking during cycling, which mimics a breathing effect at the material/electrode/cell level, leads to several coupled issues including fracture of Si particles, unstable solid electrolyte interphase, and low Coulombic efficiency. In this work, the regulation of the breathing effect is reported by using Si–C yolk–shell nanocomposite which has been well‐developed by other researchers. The focus is on understanding how the nanoscaled materials design impacts the mechanical and electrochemical response at electrode level. For the first time, it is possible to observe one order of magnitude of reduction on breathing effect at the electrode level during cycling: the electrode thickness variation reduced down to 10%, comparing with 100% in the electrode with Si nanoparticles as active materials. The Si–C yolk–shell nanocomposite electrode exhibits excellent capacity retention and high cycle efficiency. In situ transmission electron microscopy and finite element simulations consistently reveals that the dramatically enhanced performance is associated with the regulated breathing of the Si in the new composite, therefore the suppression of the overall electrode expansion.