基于MEH-PPV:PCBM体异质结的有机人工光电突触

在识别与处理视觉信息、完成复杂的学习和记忆方面,集光学传感和突触功能于一体的人工光电突触表现出巨大的优势.目前已报道的光突触器件功能实现形式相对单一且不稳定,因此需要探索更多基于新材料和新结构的突触器件,以处理复杂多变的视觉信息.本研究采用了有机半导体材料聚[2-甲氧基-5-(2-乙基己氧基)-1,4-苯乙炔](MEH-PPV)和[6,6]-苯基C61丁酸甲酯(PCBM)构建垂直型光调控忆阻器,展现了其在处理视觉信息和模拟神经形态行为方面的优异性能.该器件通过体异质结实现了稳定、缓变的阻值变化,成功模拟了电压调控的长时程增强/抑制,呈现多种光电协同调控的突触可塑性.此外,该器件还成功模拟了人类视觉神经系统中的图案识别与记忆功能,证明了其在开发下一代人工视觉系统方面的应用潜力.     

稀土基氧化物忆阻器的研究进展

忆阻器是一种将电荷和磁通量关联起来的电路学基本元器件，在量纲上它与电阻相同，表现为随电压电流变换的非线性电阻变换行为。作为一种新型的非易失性存储器件，忆阻器具有结构简单、存储密度高和能够模拟生物神经突触等特性。因其独特的“记忆特性”，在阻变存储器、人工神经网络和非线性运算电路设计等领域被广泛的研究。其中，稀土基氧化物忆阻器因其更加稳定的性能和多元的应用前景，成为忆阻器研究关注的热门材料。但目前对于稀土氧化物材料，尤其对重稀土元素并没有较为全面的总结和归纳。因此，文章从忆阻器的结构、组成和电阻转换机理进行了论述。以元素为分类标准，系统地梳理从Y元素到Lu元素，国内外每种稀土氧化物以及稀土掺杂氧化物忆阻器在阻变存储器，人工神经网络等方面应用的重点工作。最后，对目前稀土基忆阻器研究遇到的问题和挑战进行了分析，总结了稀土基氧化物忆阻器优缺点，提出了目前可行的方法，并展望了发展趋势和应用潜力。     

新型Ti3C2 MXene的化学制备及基于MXene忆阻器特性与机理

阻变器件是一种微电子器件,具有阻值可在两个甚至两个以上的阻态之间重复变化的特点。忆阻器作为新型的阻变器件,具有可连续变化的丰富阻态。近年来因其具备简单的二端结构、高集成度以及低工作电压等特性,在新型非易失性存储以及构建神经形态系统等方面被广泛研究。但其在实现应用的过程中仍存在着稳定性较差等问题。近期一些工作证明了二维材料如氧化石墨烯在优化忆阻器性能方面具备良好的应用潜力。MXene是一种具备类似石墨烯结构的新型二维过渡金属碳/氮化物,因其具备二维层状结构显现出特殊的力学以及电学特性,有望应用于忆阻器中以提高器件的电学性能。在本文中,我们通过化学湿法刻蚀制备了Ti₃C₂粉末,通过旋涂工艺在忆阻器结构中引入Ti₃C₂薄膜。Ti₃C₂ MXene与SiO₂同时作为忆阻器阻变层,制备了Cu/Ti₃C₂/SiO₂/W结构的忆阻器,并且对其相关电学特性进行了探究。在该器件上,通过实验测得忆阻器典型的开关特性曲线并在双向直流电压下针对高、低阻态的可重复性、稳定性进行了实验。结果表明该器件能够在100个扫描循环过程中保持稳定的高、低阻态达到10⁴ s以上。同时,该器件状态能够受脉冲电压调节,实现突触间典型的双脉冲易化行为。实验结果表明基于Ti₃C₂ MXene的忆阻器将有望应用于构建新兴存储设备以及人工神经形态系统。     

基于氧化铟锡电极的透明忆阻器件工作机制研究进展

随着电子技术的发展,兼具透明、柔性等特性的功能电子器件得到了广泛关注。作为新型电子存储器件,忆阻器在新一代信息技术领域(包括低功耗类脑计算、非易失逻辑、数据存储等)有着广阔的应用前景,成为近年来备受关注的新型纳米器件。氧化铟锡是一种常用的透明导电材料,因其优异的光学透明度、稳定的物理、化学特性等优点,成为制备新型透明忆阻器件的理想电极。本文首先简略介绍了忆阻器件的结构,接着综述了基于氧化铟锡材料的忆阻器件的研究和应用,包括其作为存储器、电子突触和痛觉感受器等。然后针对氧化铟锡忆阻器的阻变机制,特别是近年来新发现的铟扩散机制进行了进一步介绍,最后总结展望了氧化铟锡忆阻器的发展前景。     

有机光电突触器件的研究与进展

大脑对视觉信息学习和记忆等功能的实现是通过视觉神经元调控突触权重进行的,对光响应的突触器件是实现低能耗人工视觉系统和神经形态计算的关键.因此,近年来有机光电突触器件引起了学术界的广泛关注.本文指出有机光电突触器件结合了有机光电探测器和有机忆阻器2个基本光电子器件功能,实现对光信息的传感和记忆,介绍了光电突触器件的基本性...     

三端晶体管的人工突触器件:材料、结构与系统

神经形态工程学旨在从硬件层面上构建人工仿生神经系统,模拟人脑独特高效的运行机制,进而实现神经形态感知和类脑计算功能.生物突触是人脑学习和记忆的基本结构与功能单元.因此,构建类生物突触结构、功能的电子器件是实现神经形态感知与计算的关键.相较于两端的阻变器件,三端突触晶体管在实现多态调控和降低能量消耗上都具有优势.此外,三端突触晶体管还可以将压力、温度等外界物理刺激转化为电信号,在采集视觉、听觉、嗅觉等信号来工作的人造感知神经系统方面有广阔的应用前景.本文综述了三端突触晶体管的材料选择、器件结构以及功能应用,并重点介绍了基于三端突触晶体管的人造视觉、听觉和嗅觉三种感知系统的最新进展.最后,总结了三端突触晶体管及其构建的人造感知系统面临的挑战,并对其未来发展进行了展望.     

共价有机框架薄膜的界面生长策略及其在忆阻器中的研究进展

随着大数据和物联网时代数字通信技术的飞速发展,忆阻器在高密度数据存储技术和神经形态计算等应用中扮演着越来越重要的角色.得益于共价有机框架(COF)材料优异的可设计性及独特的光电特性,同时,伴随着液体界面辅助的制备策略不断发展与完善, COF材料在存储器件中的应用得到了极大推广.为了开发更高性能的基于COF材料的存储器件,需要全面地了解从材料设计、制备到器件应用的不断发展.因此,本综述系统地总结了COF薄膜的制备策略及其在忆阻器中应用的进展.最后,我们对基于COF存储器件的当前挑战及未来发展进行了总结与展望.     

无机固体材料中的忆阻效应

缺陷调控是固体化学中的基本问题,也是决定材料性能的核心要素。基于缺陷调控的忆阻效应将给未来电子信息领域带来全新的变革。本文综述了无机固体材料中忆阻效应的研究进展,主要总结了忆阻效应的产生机制和忆阻材料的类型,结合原子级p-n结的相关工作,提出深入明确电场下缺陷迁移机制将是从无机固体化学角度研究忆阻效应的重要方向。     

无机固体材料中的忆阻效应

缺陷调控是固体化学中的基本问题,也是决定材料性能的核心要素。基于缺陷调控的忆阻效应将给未来电子信息领域带来全新的变革。本文综述了无机固体材料中忆阻效应的研究进展,主要总结了忆阻效应的产生机制和忆阻材料的类型,结合原子级p-n结的相关工作,提出深入明确电场下缺陷迁移机制将是从无机固体化学角度研究忆阻效应的重要方向。     

溶胶凝胶法制备TiO2@Cf柔性忆阻器交叉开关

以碳纤维作为柔性衬底和电极材料,通过溶胶凝胶法在其表面镀覆TiO₂阻变活性层,进而通过“十”字搭接制备成柔性纤维忆阻器（TiO₂@C_f）。采用X射线衍射、扫描电子显微镜、X射线光电子能谱等测试手段对TiO₂@C_f结构进行表征并对其忆阻特性及阻变机理进行研究。结果表明：碳纤维上的TiO₂涂层为锐钛矿型晶体结构,其氧空位的浓度约为19.5%;制备的TiO 2@C_f柔性忆阻器为突变型忆阻器,其高低阻态阻值开关比可达10⁴;经过疲劳耐受性测试,忆阻器件的高低阻态开关比稳定在2个数量级左右。TiO₂@C_f忆阻器的机理表现为：在高阻态和低阻态时是以欧姆导电为主导的载流子输运机制,其阻态转变机制与氧空位导电细丝的形成和断裂有关。制备的TiO₂@C_f柔性忆阻器在一定程度上具有柔性弯曲变形,同时满足可编织、穿戴等功能。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).