低质量Si材料制备太阳电池

通过对比不同硼-磷(B-P)补偿程度的低成本、高杂质含量硅材料制备的太阳电池的性能,发现在含B和其它杂质含量都比较高的Si材料中通过掺入P补偿过多的B可以提高低质量Si片的电阻率、增加少数载流子寿命从而提高电池效率同时还能够减少电池性能的衰减.利用低质量Si材料(B含量2*10-6wt)制作出了效率达到14%左右的大面...     

改进的混合MAP-POCS超分辨率图像复原算法研究

超分辨率图像复原技术在不改变硬件的条件下可提高成像系统获取图像的分辨率。研究了图像退化机理,建立了精确的图像退化过程模型,提出一种改进的混合MAP-POCS复原算法,将POCS的凸集约束条件加入到MAP估计过程中。运用峰值信噪比(PSNR)等评价手段对复原图像进行质量评价。仿真结果表明,改进的混合复原算法能够有效地保证复原求解的收敛性并保持复原图像的边缘细节,提升了超分辨率的复原效果。     

一种镍基单晶高温合金中碳化物热稳定性研究

利用SEM、TEM研究了一种镍基单晶高温合金中碳化物在950℃时效不同时间的退化规律。固溶处理过程中形成的MC碳化物随时效时间的增加而逐渐退化为M6 C和M23 C6碳化物。同时,由于在时效处理过程中Re元素进入M6 C碳化物中,破坏了其结构稳定性,促使M6 C碳化物也可以退化为M23 C6碳化物。至时效3000 h时,没有观察到碳化物退化的逆反应。本研究可以为高温合金高温下服役的稳定性提供实验参考。     

Stability of Flip-Chip Interconnects Assembled with Al/Ni(V)/Cu-UBM and Eutectic Pb-Sn Solder During Exposure to High-Temperature Storage

The thermal stability of flip-chip solder joints made with trilayer Al/Ni(V)/Cu underbump metalization (UBM) and eutectic Pb-Sn solder connected to substrates with either electroless Ni(P)-immersion gold (ENIG) or Pb-Sn solder on Cu pad (Cu-SOP) surface finish was determined. The ENIG devices degraded more than 50 times faster than the Cu-SOP devices. Microstructural characterization of these joints using scanning and transmission electron microscopy and ion beam microscopy showed that electrical degradation of the ENIG devices was a direct result of the conversion of the as-deposited Ni(V) barrier UBM layer into a porous fine-grained V₃Sn-intermetallic compound (IMC). This conversion was driven by the Au layer in the ENIG surface finish. No such conversion was observed for the devices assembled on Cu-SOP surface finish substrates. A resistance degradation model is proposed. The model captures changes from a combination of phenomena including increased (1) intrinsic resistivity, (2) porosity, and (3) electron scattering at grain boundaries and surfaces. Finally, the results from this study were compared with results found in a number of published electromigration studies. This comparison indicates that degradation during current stressing in the Pb-Sn bump/ENIG system is in part due to current-crowding-induced Joule heating and the thermal gradients that result from localized Joule heating.     

RBF网络用于性能退化的可靠性评估

针对无法用数学式准确描述退化量与环境因子间复杂非线性关系的问题,提出了一种基于RBF网络的退化轨迹建模方法.利用RBF网络能够逼近任意非线性函数的特性,进行退化轨迹的建模,并结合失效值预测产品寿命.将所有估计寿命作为完全失效数据进行可靠性评估,有效地解决了失效数据少的问题.通过对疲劳裂纹增长数据的RBF网络建模分析,证明RBF网络具有很好的函数逼近能力,寿命预测结果非常理想.经验证,在更少的退化数据下,RBF网络仍能够较好地模拟退化轨迹,寿命预测精度较高.     

Gaining Insight into the Effect of Organic Interface Layer on Suppressing Ion Migration Induced Interfacial Degradation in Perovskite Solar Cells

Ion migration induced interfacial degradation is a detrimental factor for the stability of perovskite solar cells (PSCs) and hence requires special attention to address this issue for the development of efficient PSCs with improved stability. Here, an “S‐shaped, hook‐like” organic small molecule, naphthalene diimide derivative (NDI‐BN), is employed as a cathode interface layer (CIL) to tailor the [6,6]‐phenylC61‐butyric acid methylester (PCBM)/Ag interface in inverted PSCs. By realizing enhanced electron extraction capability via the incorporation of NDI‐BN, a peak power conversion efficiency of 21.32% is achieved. Capacitance–voltage measurements and X‐ray photoelectron spectroscopy analysis confirmed an obvious role of this new organic CIL in successfully blocking ionic diffusion pathways toward the Ag cathode, thereby preventing interfacial degradation and improving device stability. The molecular packing motif of NDI‐BN further unveils its densely packed structure with π–π stacking force which has the ability to effectually hinder ion migration. Furthermore, theoretical calculations reveal that intercalation of decomposed perovskite species into the NDI clusters is considerably more difficult compared with the PCBM counterparts. This substantial contrast between NDI‐BN and PCBM molecules in terms of their structures and packing fashion determines the different tendencies of ion migration and unveils the superior potential of NDI‐BN in curtailing interfacial degradation.     

一种基于退化数据的元器件可靠性定量检验方法研究

针对高可靠元器件可靠性鉴定中缺乏可靠性级别定量评价的问题,基于失效物理,分析了键合强度参数退化及失效判据,并给出了退化模型的数学表达和参数估计方法,研究基于退化量分布的可靠性定量检验方法,并采用AD厂家的AD524SD作为试验器件,进行了相应的试验分析和验证。结果表明,提出的高可靠性级别器件鉴定检验方法具有很好的工程适用性和应用价值。     

Kinetics of light-induced degradation in compensated boron-doped silicon investigated using photoluminescence and numerical simulation

We use photoluminescence to observe light-induced degradation in silicon in real time. Numerical simulations are used to match our results and lifetime decay data from the literature with theoretical models for the generation of the light-induced boron–oxygen defects. It is found that the existing model of the slowly generated defect SRC, where its saturated concentration is a function of the majority carrier concentration, does not explain certain results in both p- and n-type samples. A new model is proposed in which the saturated SRC concentration is controlled by the total hole concentration under illumination.     

Bottom‐Up Preparation of Fully sp2‐Bonded Porous Carbons with High Photoactivities

Porous carbons, possessing exceptional stability, high surface area, and electric conductivity, are broadly used as superior adsorbent, supporter, or electrode material for environmental protection, industrial catalysis, and energy storage and conversion. The construction of such kinds of materials with designable structures and properties will extremely extend their potential applications, but remains a huge synthetic challenge. Herein, a bottom‐up approach is presented to synthesize one type of fully sp² carbon–bonded frameworks by transition metal–catalyzed cross‐coupling of different polyphenylenes with electron‐withdrawing 9,9′‐bifluorenylidene (9,9′‐BF) through its 2,7‐position. The resulting porous polymeric carbons exhibit substantial semiconducting properties, such as strong light‐harvesting capabilities in the visible light region, likely due to their π‐extended backbones with donor–acceptor characters. Their electronic and porous structures can be finely tuned via the polyphenylene spacers. The intriguing properties allow these porous carbons to efficiently catalyze dye degradation under visible light or even natural sunlight with high reusability. Meanwhile, associated with their intrinsic structures, these porous carbons also exhibit highly selective degradation activities toward different dyes. In particular, the photodegradation mechanism involving oxygen and electron is elucidated for the first time for such kinds of materials, related to the presence of specific 9,9′‐BF units in their π‐conjugated skeletons.