Improved Charge Generation via Ultrafast Effective Hole‐Transfer in All‐Polymer Photovoltaic Blends with Large Highest Occupied Molecular Orbital (HOMO) Energy Offset and Proper Crystal Orientation

Improved charge generation via fast and effective hole transfer in all‐polymer solar cells (all‐PSCs) with large highest occupied molecular orbital (HOMO) energy offset (ΔE_H) is revealed utilizing ultrafast transient absorption (TA) spectroscopy. Blending the same nonfullerene acceptor poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene) (N2200) with three different donor polymers produces all‐polymer blends with different ΔE_H. The selective excitation of N2200 component in blends enables to uncover the hole transfer process from hole polaron‐induced bleaching and absorption signals probed at different wavelength. As the ΔE_H is enhanced from 0.14 to 0.37 eV, the hole transfer rate rises more than one order and the hole transfer efficiency increases from 12.9% to 86.8%, in agreement with the trend of internal quantum efficiency in the infrared region where only N2200 has absorption. Additionally, Grazing‐incidence wide‐angle X‐ray scattering measurements indicate that face‐on crystal orientation in both polymer donor and acceptor also plays an important role in facilitating the charge generation via hole transfer in all‐PSCs. Hence, large ΔE_H and proper crystal orientation should be considered in material design for efficient hole transfer in N2200‐based heterostructures. These results can provide valuable guidance for fabrication of all‐PSCs to further improve power conversion efficiency.     

Recent Progress in Applications of the Cold Sintering Process for Ceramic–Polymer Composites

Ceramic–polymer composites are of interest for designing enhanced and unique properties. However, the processing temperature windows of sintering ceramics are much higher than that of compaction, extrusion, or sintering of polymers, and thus traditionally there has been an inability to cosinter ceramic–polymer composites in a single step with high amounts of ceramics. The cold sintering process is a low‐temperature sintering technology recently developed for ceramics and ceramic‐based composites. A wide variety of ceramic materials have now been demonstrated to be densified under the cold sintering process and therefore can be all cosintered with polymers from room temperature to 300 °C. Here, the status, understanding, and application of cold cosintering, with different examples of ceramics and polymers, are discussed. One has to note that these types of cold sintering processes are yet new, and a full understanding will only emerge after more ceramic–polymer examples emerge and different research groups build upon these early observations. The general processing, property designs, and an outlook on cold sintering composites are outlined. Ultimately, the cold sintering process could open up a new multimaterial design space and impact the field of ceramic–polymer composites.     

Phenyl Selenosulfides as Cathode Materials for Rechargeable Lithium Batteries

The Se? Se bond in an organo‐diselenide (RSeSeR, R is an organic group) can break in a 2e^? reduction reaction, but it has limited capacity as a cathode material for rechargeable lithium‐ion batteries. To increase its capacity, redox active species (e.g., sulfur) can be added in the middle of the selenium atoms. Herein, phenyl diselenide (PDSe, PhSeSePh) is mixed with sulfur to form two hybrid compounds with 1:1 and 1:2 molar ratios, which almost double and triple the capacity of PDSe, respectively. Theoretical calculations suggest that phenyl selenosulfide (PDSe‐S, PhSe‐S‐SePh) and phenyl selenodisulfide (PDSe‐S₂, PhSe‐SS‐SePh) can form via addition reactions, which is supported by mass spectrometry analysis. The hybrid materials exhibit three highly reversible redox plateaus and enhanced cycling stability due to the reduced solubility of the discharge products. PDSe‐S and PDSe‐S₂ show initial capacities of 252 and 330 mAh g^?1, respectively, followed by stable cycling performance with a capacity retention of >73% after 200 cycles at C/5 rate. In addition, they show steady rate capabilities. This study reports a novel strategy to increase the electrochemical performance of organo‐diselenide by addition of sulfur.     

Electrospinning Synthesis of Self-Standing Cobalt/Nanocarbon Hybrid Membrane for Long-Life Rechargeable Zinc–Air Batteries

Integrating high-efficiency oxygen electrocatalyst directly into air electrodes is vital for zinc–air batteries to achieve higher electrochemical performance. Herein, a self-standing membrane composed of hierarchical cobalt/nanocarbon nanofibers is fabricated by the electrospinning technique. This hybrid membrane can be directly employed as the bifunctional air electrode in zinc–air batteries and can achieve a high peak power density of 304 mW cm⁻² with a long service life of 1500 h at 5 mA cm⁻². Its assembled solid-state zinc–air battery also delivers a promising power density of 176 mW cm⁻² with decent flexibility. The impressive rechargeable battery performance would be attributed to the self-standing membrane architecture integrated by oxygen electrocatalysts with abundant cobalt–nitrogen–carbon active species in the hierarchical electrode. This study may provide effective electrospinning solutions in integrating efficient electrocatalyst and electrode for energy storage and conversion technologies.     

H.264视频编码的嵌入式系统实现

H.264是ITU-T组织针对实时视频通讯应用制定的新一代视频压缩标准,开发H.264的嵌入式视频系统有重要的意义.该文在深入研究H.264标准和嵌入式系统的基础上,设计了一种以TI公司的TMS320C6416DSP为核心处理器的嵌入式视频编码系统,系统主要包括视频解码,视频转换,采集视频缓冲区管理,编码及码流输出等.对于系统实现中所涉及的视频转换,内存管理机制,代码优化等进行了详细的讨论.     

计算机软件估计技术及未来发展

计算机软件估计对项目的软件规模进行数字上的近似.从而可以制定或更新项目开发计划,指导开发过程,文中对软件估计中常用的技术进行了分析.这些技术包括Wideband Delphi,Pert Sizing以及功能点方法.最后指出了软件估计技术未来发展的趋势.     

一种新的消除VV算法载波相位模糊的方法

VV算法非常适用于PSK突发信号的载波同步。该算法需要对估计出来的相位进行后续处理,以消除由剩余频差引起的相位模糊、避免跳周现象。该文提出了一种新的相位后续处理方法,不但能够消除由剩余频差带来的相位模糊,而且对于由噪声引入的相位模糊仍然非常有效。相对于已有的方法,该方法大大降低了信号发生跳周的概率。计算机仿真表明,该方法具有良好的性能,适用于对MPSK突发信号的解调。     

大规模集成电路浮栅ROM器件总剂量辐射效应

提出了一种大规模集成电路总剂量效应测试方法:在监测器件和电路功能参数的同时,监测器件功耗电流的变化情况,分析数据错误和器件功耗电流与辐射总剂量的关系.根据该方法利用60Co γ射线进行了浮栅ROM集成电路(AT29C256)总剂量辐照实验,研究了功耗电流和出错数量在不同γ射线剂量率辐照下的总剂量效应,以及参数失效与功能失效时间随辐射剂量率的变化关系,并利用外推实验技术预估了电路在空间低剂量率环境下的失效时间.     

一种有机/金属肖特基二极管的实验研究

提出了一种简单有效的有机/金属肖特基二极管的制备方法:通过简单的真空气相沉积工艺,依次将有机材料PTCDA(C24H8O6)薄膜和金属电极Au蒸镀在透明导电玻璃ITO上.通过在室温条件下对该二极管的电流-电压(I-V)特性的测试发现,其整流系数可达104.根据标准肖特基理论以及实验所得电容-频率(C-f)和电容-电压(C-V)的测试结果,得到该有机肖特基势垒高度在0.2～0.3eV范围内.