Tuning the Intermolecular Electrostatic Interaction toward High-Efficiency and Low-Cost Organic Solar Cells

Organic solar cells (OSCs) have achieved much progress with rapidly increasing power conversion efficiencies (PCEs). It should be noted that the top-performance OSCs are generally consisted of active materials with complex chemical structures, resulting in high costs. Here, combining the material design and morphology control, high-efficiency OSCs are fabricated by a low-cost donor: acceptor blend. A completely non-fused electron acceptor named Tz is designed and synthesized via introducing thiazole units on both sides of a bithiophene core, which shows an outstanding PCE of 13.3% with a typical polythiophene donor. More importantly, optimization guidelines are presented to get excellent morphology for low-cost donor:acceptor systems. Three polythiophenes are selected, poly(3-hexylthiophene) and its two derivatives with electron-withdrawing substitutions (PDCBT and PDCBT-2F), as donors to fabricate the cell devices. The computational and experimental data reveal that decreasing the electrostatic interaction between polythiophene and Tz is the key to getting a suppressed miscibility and thus a high phase purity. This study provides insight into the molecular design and donor:acceptor matching requirements for high-efficiency and low-cost OSCs.     

Simultaneous CO2 and H2O Activation via Integrated Cu Single Atom and N Vacancy Dual-Site for Enhanced CO Photo-Production

Photocatalytic conversion of CO₂ into fuels using pure water as the proton source is of immense potential in simultaneously addressing the climate-change crisis and realizing a carbon-neutral economy. Single-atom photocatalysts with tunable local atomic configurations and unique electronic properties have exhibited outstanding catalytic performance in the past decade. However, given their single-site features they are usually only amenable to activations involving single molecules. For CO₂ photoreduction entailing complex activation and dissociation process, designing multiple active sites on a photocatalyst for both CO₂ reduction and H₂O dissociation simultaneously is still a daunting challenge. Herein, it is precisely construct Cu single-atom centers and two-coordinated N vacancies as dual active sites on CN (Cu₁/N_2CV-CN). Experimental and theoretical results show that Cu single-atom centers promote CO₂ chemisorption and activation via accumulating photogenerated electrons, and the N_2CV sites enhance the dissociation of H₂O, thereby facilitating the conversion from COO* to COOH*. Benefiting from the dual-functional sites, the Cu₁/N_2CV-CN exhibits a high selectivity (98.50%) and decent CO production rate of 11.12 µmol g⁻¹ h⁻¹. An ingenious atomic-level design provides a platform for precisely integrating the modified catalyst with the deterministic identification of the electronic property during CO₂ photoreduction process.     

基于BSO的液晶空间光调制器

紫外光敏材料硅酸铋(BSO)在短波长的蓝紫光激励下电阻率会急剧降低,可作为良好的光信息写入材料,用作光寻址的液晶空间光调制器(LC-SLM)的感光层.介绍了以BSO为基的光寻址透射式液晶空间光调制器的结构和工作原理,从BSO晶体产生光电导效应的机理出发,得到了光电流和光照功率的关系.实验测量了BSO晶体片在不同频率和不同强度的光照下的光电响应.通过对液晶分子指向矢分布随电压变化的理论计算,得到了在不同光照强度下BSO基的液晶空间光调制器产生的光程差,与实验中液晶盒在不同电压下产生的光程差有相同的变化趋势.     

一种基于HVS的多重水印技术

提出一种新的算法,利用混沌对水印图像进行置乱,并且在图像的低频分量和高频分量中同时嵌入水印,这样在图像处理后,可以使一个水印较好的保存下来.低频分量集中图像的大部分能量,修改系数容易引起失真,所以在低频分量嵌入水印时利用人眼视觉特性(HVS),经过实验证明这种算法具有较强不可见性和鲁棒性.     

基于E型双模谐振器的源负载耦合带通滤波器设计

为实现滤波器的小型化和高性能,提出了两款中心加载的E型双模谐振器,并对其进行了奇偶模分析。在此基础上通过引入源负载耦合,采用ADS与HFSS软件进行了仿真与优化。开路支节加载与短路支节加载的E型双模谐振器分别比方环谐振器减少42.8%与52.6%。实测结果表明,设计的滤波器中心频率分别为4.22 GHz和3.75 GHz,相对带宽分别为33.6%和9.1%,带内插损分别为-0.9 dB和-1.9 dB,带外零点位置与计算仿真结果吻合良好。这两款滤波器不仅尺寸小、插损低,并且具有宽阻带、传输零点可调的优点,短路支节加载的双模滤波器在选择性与带外抑制方面性能更好,可以广泛应用于各种微波电路中。     

基于互信息的MIMO雷达通信一体化系统的性能分析

该文讨论共存式多输入多输出(Multiple-input multiple-output,MIMO)雷达通信一体化系统的性能.雷达端和通信端采用合作的方式共享信息,使得一体化系统的通信端可以利用雷达信号来辅助完成通信任务,而雷达端则可利用被动的通信信号来完成雷达任务.该文推导合作情况下共存一体化MIMO系统的雷达互信息...     

宽带信号的失真分析与改善

高分辨雷达需要高质量的宽带信号,工程中的发射激励信号由于存在宽带失真,大大限制了信号处理的脉冲压缩性能。本文从一种宽带波形产生器的研制入手,分析了信号产生中出现宽带失真的原因及表现形式,并通过预失真等数字校正的方法,改善了宽带发射激励信号的质量,获得了满意的脉压效果。     

热挤压AZ91D镁合金线材的组织与性能研究

对铸态AZ91D合金进行400~460℃不同温度下的正挤压,制备出直径为3~4 mm的线材。利用光学显微镜分析线材的组织,测试其拉伸力学性能和热膨胀系数。结果表明,在不同挤压温度下均可制备出AZ91D镁合金线材,挤压温度越低,线材晶粒越细小。线材具有优异的力学性能,经400℃热挤压成形的线材抗拉强度和伸长率高达285.6 MPa和5.3%,明显高于同牌号铸态合金的性能。线材的平均线膨胀系数为(21.3~27.4)×10-6K-1。较低挤压温度下制备的线材具有较高的力学性能与较小的线膨胀系数。     

鱼雷战斗部技术研究现状及发展趋势

鉴于鱼雷战斗部技术的研究现状,通过以下5方面分析并展望了提高鱼雷战斗部爆炸威力的途径：研究新型战斗部结构,实现定向聚能爆破;研究新型高能炸药,提高战斗部的毁伤威力;加大鱼雷口径,大幅度增加装药量;采用先进工艺,提高炸药的装填密度;在必要情况下,采用核装药。提出了改进建议：在逐步提高研究手段和加强条件保障建设基础上重点开展鱼雷战斗部数值仿真研究和水下爆炸试验研究。     

新一代网络体系--智能光网络

首先介绍了传统的电信网络架构,指出其存在的问题并引出了新一代网络体系-智能光网络;然后说明了智能光网络的基本原理和它带来的巨大影响;最后描述了智能光网络的演进过程,并指出ASON的出现,将深刻地改变了光传输网的体系和功能。