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.     

Thermally Controlled,Active Imperceptible Artificial Skin in Visible‐to‐Infrared Range

Cephalopods’ extraordinary ability to hide into any background has inspired researchers to reproduce the intriguing ability to readily camouflage in the infrared (IR) and visible spectrum but this still remains as a conundrum. In this study, a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with a flexible bi‐functional device (active cooling and heating) is developed. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum (thus visible‐to‐IR) and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt to the background of the sophisticated pattern with higher resolution and eventually heightening the level of imperceptibility. As this proof‐of‐concept can be directly worn and conceals the human skin in multispectral ranges, the work is expected to contribute to the development of next‐generation soft covert military wearables and perhaps a multispectral cloak that belongs to cephalopods or futuristic camouflage gadgets in the movies.     

巧用MAX706

美信公司（ＭＡＸＩＭ）的ＭＡＸ７０６是目前广泛应用、功能完善的微处理器监控电路。本文总结了一些该芯片在实用中的经验。     

Transmission Characteristics of Multi-Soliton Train in Twin-Core Fiber

Transmission characteristics of multisoliton train are analyzed by numerical simulation in twin-core fiber. It is shown that stable transmission of multisoliton train requires some difference of initial relative phase and enough initial relative separation between input solitons under strong coupling between two cores.     

Evaluating the generalization ability of convolutional neural networks for built-up area extraction in different cities of China

The difficulty of build-up area extraction is due to complexity of remote sensing data in terms of heterogeneous appearance with large intra-class variations and lower inter-class variations. In order to extract the built-up area from Landsat 8-OLI images provided by Google earth engine(GEE), we propose a convolutional neural networks(CNN) utilizing spatial and spectral information synchronously, which is built in Google drive using Colaboratory-Keras. To train a CNN model with good generalization ability, we choose Beijing, Lanzhou, Chongqing, Suzhou and Guangzhou of China as the training sites, which are very different in term of natural environments. The Arc GIS-Model Builder is employed to automatically select 99 332 samples from the 38-m global built-up production of the European Space Agency(ESA) in 2014. The validate accuracy of the five experimental sites is higher than 90%. We compare the results with other existing building data products. The classification results of CNN can be very good for the details of the built-up areas, and greatly reduce the classification error and leakage error. We applied the well-trained CNN model to extract built-up areas of Chengdu, Xi’an, Zhengzhou, Harbin, Hefei, Wuhan, Kunming and Fuzhou, for the sake of evaluating the generalization ability of the CNN. The fine classification results of the eight sites indicate that the generalization ability of the well-trained CNN is pretty good. However, the extraction results of Xi’an, Zhengzhou and Hefei are poor. As for the training data, only Lanzhou is located in the northwest region, so the trained CNN has poor image classification ability in the northwest region of China.     

Demonstration of aluminum-free metamorphic InP/In0.53Ga0.47As/InP double heterojunction bipolar transistors on GaAssubstrates

We report, for the first time, the successful fabrication of aluminum-free metamorphic (MM) InP/In_0.53 Ga_0.47 As/InP double heterojunction bipolar transistors (DHBTs) on GaAs substrates with a linearly graded In_xGa_1-xP buffer grown by solid-source molecular beam epitaxy (SSMBE). Devices with 5×5 μm² emitters display a peak current gain of 40 and a common-emitter breakdown voltage (BV_CE0) higher than 9 V, a current gain cut-off frequency (f_T) of 48 GHz and a maximum oscillation frequency (f_max) of 42 GHz. A minimum noise figure of 2.9 dB and associated gain of 19.5 dB were measured at a collector current level of 2.6 mA at 2 GHz. Detailed analysis suggests that the degradation of the base-emitter heterojunction interface and the increase of bulk recombination are the most probable causes for the poorer device performance of current metamorphic HBTs compared with lattice-matched HBTs     

粉末冶金制品激光熔覆组织与性能研究

本文对常规烧结的铁基粉末冶金制品表面激光熔覆处理进行了研究,采用SEM和TEM对熔覆样品的显微组织进行了观察,测试与分析了其孔隙度和显微硬度,结果表明:熔覆层组织为γ+M7C3共晶,表层硬度显著提高而整体孔隙度降低。粉末冶金工艺特有的优越性(如制取高纯度及各种复杂形状的零件)使得粉末冶金零件在工业中得到了越来越广泛的应用,如汽车、摩托车用活塞,内燃机上的排气阀座和低压怕泵齿轮等[1]。常规烧结方法一般采用添加大量的合金元素及烧结过程中加压等处理来达到要求。激光熔覆合金覆层技术作为新兴的表面改性技术近年来得到了迅速…     

MPLS的框架及其关键技术

ＭＰＬＳ（Ｍｕｌｔｉｐｒｏｔｏｃｏｌ ａｂｅｌ Ｓｗｉｔｃｈｉｎｇ：多协议标记交换）还是一项非常不成熟的技术,它目前正在由ＩＥＴＦ进行标准化。对ＭＰＬＳ的工过程进行了回顾,然后介绍了ＭＰＬＳ的体系结构,最后论述了ＭＰＬＳ目前急需解决的一些关键技术。     

半导体量子点的电容

当电子数目很少量,用简谐势来描述量子点中电子所受的约束是一种很准确的近似。文章利用量子力学中的少体理论方法研究了二电子系统和三电子系统的行为。少体理论可以把质心运动和相对运动分离,从而得到精确的数值解。利用单个电子在量子点中的基态波函数的束缚行为,选择了量子点的束缚能。通过对ＣｄＳ、ＰｂＳ等半导体纳米粒子的充电电容的计算找到了其在室温下形成单电子器件的最大粒径。