Incorporating Graphitic Carbon Nitride (g‐C3N4) Quantum Dots into Bulk‐Heterojunction Polymer Solar Cells Leads to Efficiency Enhancement

Graphitic carbon nitride (g‐C₃N₄) has been commonly used as photocatalyst with promising applications in visible‐light photocatalytic water‐splitting. Rare studies are reported in applying g‐C₃N₄ in polymer solar cells. Here g‐C₃N₄ is applied in bulk heterojunction (BHJ) polymer solar cells (PSCs) for the first time by doping solution‐processable g‐C₃N₄ quantum dots (C₃N₄ QDs) in the active layer, leading to a dramatic efficiency enhancement. Upon C₃N₄ QDs doping, power conversion efficiencies (PCEs) of the inverted BHJ‐PSC devices based on different active layers including poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61‐butyric acid methyl ester (P3HT:PC₆₁BM), poly(4,8‐bis‐alkyloxybenzo(l,2‐b:4,5‐b′)dithiophene‐2,6‐diylalt‐(alkyl thieno(3,4‐b)thiophene‐2‐carboxylate)‐2,6‐diyl):[6,6]‐phenyl C₇₁‐butyric acid methyl ester (PBDTTT‐C:PC₇₁BM), and poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐co‐3‐fluorothieno [3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th):PC₇₁BM reach 4.23%, 6.36%, and 9.18%, which are enhanced by ≈17.5%, 11.6%, and 11.8%, respectively, compared to that of the reference (undoped) devices. The PCE enhancement of the C₃N₄ QDs doped BHJ‐PSC device is found to be primarily attributed to the increase of short‐circuit current (J_sc), and this is confirmed by external quantum efficiency (EQE) measurements. The effects of C₃N₄ QDs on the surface morphology, optical absorption and photoluminescence (PL) properties of the active layer film as well as the charge transport property of the device are investigated, revealing that the efficiency enhancement of the BHJ‐PSC devices upon C₃N₄ QDs doping is due to the conjunct effects including the improved interfacial contact between the active layer and the hole transport layer due to the increase of the roughness of the active layer film, the facilitated photoinduced electron transfer from the conducting polymer donor to fullerene acceptor, the improved conductivity of the active layer, and the improved charge (hole and electron) transport.     

Tunable Optical Mode Ferromagnetic Resonance in FeCoB/Ru/FeCoB Synthetic Antiferromagnetic Trilayers under Uniaxial Magnetic Anisotropy

Ferromagnetic resonance (FMR) is one of the most important characteristics of soft magnetic materials, which practically sets the maximum operation speed of these materials. There are two FMR modes in exchange coupled ferromagnet/nonmagnet/ferromagnet sandwich films. The acoustic mode has relatively lower frequency and is widely used in radio‐frequency/microwave devices, while the optical mode is largely neglected due to its tiny permeability even though it supports much higher frequency. Here, a realistic method is reported to enhance the permeability in the optical mode to an applicable level. FeCoB/Ru/FeCoB trilayers are carefully engineered with both uniaxial magnetic anisotropy and antiferromagnetic interlayer exchange coupling. This special magnetic structure exhibits a high optical mode frequency up to 11.28 GHz and a maximum permeability of 200 at resonance. An abnormally low inverse switch field (<200 Oe, less than 1/5 of the single layer) is observed which can effectively switch the system from optical mode with higher frequency into acoustic mode with lower frequency. The optical mode frequency and inverse switch field can be controlled by tailoring the interlayer coupling strengths and the uniaxial anisotropy fields, respectively. The tunable optical mode resonance thus can increase operation frequency while reduce operation field overhead in FMR based devices.     

以铜包铝线为内导体的CATV同轴电缆的特性

铜包铝线是 CATV同轴电缆纯铜线内导体的“更新换代”产品。本文阐述了铜包铝线的规格及对铜包铝线质量和性能的要求 ,介绍了国内用包覆焊接法生产的铜包铝线的特性 ,以及用国产铜包铝线制成的同轴电缆的特性。     

一种新颖的多功能低相移DC-50 GHz单片可变衰减器

Ga As MMIC控制电路开关由于其体积小、重量轻、开关速度快、抗辐射、可靠性高等显著优点在许多电子系统和电子设备中得到广泛应用 ,南京电子器件研究所最近研究出一种新颖的多功能低相移 DC- 5 0 GHz高性能单片压控可变衰减器 ,获得了优异电性能。据了解 ,这是世界上第一次报道这种具有低相移功能的 DC- 5 0 GHz单片压控可变衰减器 ,国外的类似产品不具备这种低相移功能 ,同时还采用了直流参考电路和 MBE外延材料及相关工艺技术制造 ,不仅电路复杂 ,给工艺成品率、可靠性和成本带来不利 ,同时还会带来功耗(标称最大直流功耗 1 5 2 m…     

基于UWB的Ad hoc无线网络

介绍了采用超宽带(UWB)技术的Ad hoc无线网络,重点阐述了网络的两个关键技术MAC协议和路由算法协议.     

Slow-Scale and Fast-Scale Instabilities in Voltage-Mode Controlled Full-Bridge Inverter

This paper discusses the slow-scale and fast-scale instabilities of a voltage-mode controlled full-bridge inverter which is widely used in AC power supply applications. The main results are illustrated by exact cycle-by-cycle simulations. It is shown that the slow-scale instability is a type of low-frequency instability which manifests itself as a Hopf-type low-frequency oscillation in the whole line cycle, whereas the fast-scale instability is a type of local instability which manifests itself as a period-doubling bifurcation in some intervals of a line cycle. An averaged model and an improved discrete-time model are used to theoretically analyze the slow-scale and fast-scale instabilities, respectively. Finally, experimental results are presented to verify the results from simulations and analysis. Our work has revealed more instabilities which are likely to occur in the inverter, and has provided a convenient means of predicting stability boundaries to facilitate the design of the inverter.     

Vesicle‐Assisted Assembly of Mesoporous Ce‐Doped Pd Nanospheres with a Hollow Chamber and Enhanced Catalytic Efficiency

Mesoporous Ce‐doped Pd nanospheres with a hollow chamber are synthesized by chemical reduction of PdCl₂ with KBH₄ in an aqueous solution containing Ce(NO₃)₃ and Bu₄PBr. The later acts as a template for the hollow chamber via forming organic vesicles. During the liquid‐phase phenol hydrogenation to cyclohexanone, the as‐prepared catalyst exhibits a much‐higher activity than the corresponding solid nanoparticle catalyst prepared in the absence of Bu₄PBr. Meanwhile, the Ce dopants greatly enhance the activity and selectivity to cyclohexanone. The hollow chamber is quite stable against heating in solution and the catalyst could be used repetitively many times. Such a catalyst shows a good potential in industrial applications.     

双股射流壁面脉动压强与近壁紊动流速相关与频谱特性

本文用多通道动态压力检测系统和二维激光测速仪对在单股和双股射流作用下,水垫塘底板脉动压强与近壁脉动流速的相关,功率谱和紊动比尺进行了测试研究。实测表明,双股射流形成的动水扩建在塘底水平方向的脉动使得双股射流在第二冲击点下游的脉动量特性与单股射流不同：前者的水平脉动速度与脉动压强的互相关系数较后者明显增大,且水平脉动速度和脉动压强的功率谱具有大致相同的优势频率。单股和双股射流塘底脉动压强系数与近壁紊     

颗粒与高频感应热等离子体流相互作用的数值研究

通过颗粒对等离子体反影响的研究，可以有效控制颗粒在等离子体中的运动轨迹及其在高温区的停留时间，达到对颗粒有效加工的目的。本文通过对高频感应热等离子体流温度场与速度场和颗粒运动轨迹与加热过程进行选代计算，给出了颗粒加热与加速对高频感应热等离子体流反影响的一些数值模拟结果     

三峡二期上游围堰防渗工程若干问题的研究

二期上游围堰施工直接关系到三峡工程的总工期，工程量大，工期紧、施工强度高、防渗基础复杂是影响三峡工程施工成败的关键性项目之一。二期上游围堰在设计洪水时，库内蓄洪容积达２０亿ｍ＾３，万一失事，将造成工程及下游生命财产的重大损失，其重要性物技术复杂不是一般围堰工程所能比拟的，许多专家都指出：“二期围堰关键在防渗工程”。