纳米间隙电极的制备及应用

综述了国内外纳米间隙电极的制备方法,其中主要包括扫描隧道显微镜法、Hg滴法、机械断裂法、微加工法、电迁移法、电化学法等,对每种方法的制备过程及原理进行了较详细的介绍;对每种纳米间隙电极在分子电子学方面的应用,特别是对利用纳米间隙电极测定单分子的I-V性质、制作分子整流器和分子晶体管等工作做了简单介绍。突出了纳米间隙电极在分子器件研究中的重要作用;最后讨论了分子电子学所面临的一些问题并对该领域的发展方向作出了展望。     

石墨烯-ZnO复合纳米材料中的电荷转移

为研究石墨烯-ZnO复合纳米材料中的电荷转移情况,将化学气相沉积法生长的石墨烯转移到SiO2/Si衬底上,用电子束曝光的方法制备金电极后,再通过热蒸发的方法生长了ZnO纳米颗粒,得到G-ZnO复合纳米材料的场效应管器件。通过研究紫外光照对该器件转移曲线的影响,探究了该复合材料中的电荷转移机理,观察到电子从ZnO纳米颗粒到石墨烯的转移。     

分子组装及其应用

在对分子组装及其应用于功能纳米结构或器件的研究进展进行了较系统分析的同时,介绍了东南大学纳米科学与技术研究中心在这方面所开展的一些工作,包括基于微细加工结合分子组装制备纳米间隙电极,金属纳米微粒的二维有序排列,单电子原型器件的研制与仿真,以及采用分子组装进行核壳结构复合材料制备等方面的研究.     

分子组装及其应用

在对分子组装及其应用于功能纳米结构或器件的研究进展进行了较系统分析的同时,介绍了东南大学纳米科学与技术研究中心在这方面所开展的一些工作,包括基于微细加工结合分子组装制备纳米间隙电极,金属纳米微粒的二维有序排列,单电子原型器件的研制与仿真,以及采用分子组装进行核壳结构复合材料制备等方面的研究.     

分子组装及其应用

在对分子组装及其应用于功能纳米结构或器件的研究进展进行了较系统分析的同时，介绍了东南大学纳米科学与技术研究中心在这方面所开展的一些工作，包括基于微细加工结合分子组装制备纳米间隙电极，金属纳米微粒的二维有序排列，单电子原型器件的研制与仿真，以及采用分子组装进行核壳结构复合材料制备等方面的研究。     

电化学剥离制备石墨烯及其光电特性研究进展

石墨烯是一种新型的二维纳米碳材料,具有优良的物理、化学和机械性能,在储能器件、电子器件以及复合材料等诸多领域有广阔的应用前景。石墨烯的产业化生产一直是现在国际上材料科学研究的热点。在石墨烯的诸多制备方法中,电化学剥离方法具有快速高效、绿色环保等特点,有望实现产业化。首先综述了最近国内外电化学剥离法制备石墨烯和类石墨烯材料(BN和MoS2)的研究进展,并对其反应机理进行了探讨,然后简单介绍了石墨烯在光电子器件领域的研究现状和应用,最后对石墨烯前景进行了展望。     

石墨烯异质结及其光电器件的研究进展

石墨烯是具有高迁移率、高热导率、高比表面积、高透过率及良好的机械强度等特性的二维材料,在光电子器件领域被广泛用作透明电极及电荷传输层等。但由于石墨烯是零带隙材料,为半金属性,限制了其在半导体光电子器件领域的应用。为更加切合半导体产业应用的要求,构建异质结已经成为相关领域实现应用的重要途径。国际上已有较多团队开展了石墨烯异质结相关研究,目前已有较多报道。本文从石墨烯的性质出发,讲述了石墨烯异质结的发展历程,制备方法,并从材料制备与器件结构的角度总结了基于石墨烯异质结光电子器件的研究进展。最后,对石墨烯异质结在光电子器件领域的发展进行了展望。     

提高硅纳米墙光电器件背部欧姆接触的超声修饰方法

提供了一种硅纳米墙结构器件的背面电极接触改善方法。通过利用超声的方法修饰金属催化法制备的硅纳米墙结构,并制备了AZO／硅纳米墙异质结光电器件。研究发现超声波可以对金属催化法制备的纳米硅墙进行单面修饰,与未经超声修饰的样品制备的器件相比,超声修饰能够改善硅纳米墙器件的背面电极欧姆接触,2 min的超声修饰可以将器件的串联电阻从587 Ω下降到082 Ω,填充因子提高86％,光电转换效率提高762％,提高了光电器件的载流子收集效率。     

用化学镀方法在不同衬底上制备纳米尺度金属插塞电极的研究

纳米尺度金属插塞电极在现代纳米电子学中有很重要的应用价值。本文研究了用化学镀方法制备纳米尺度金属插塞电极,具有简单、低成本和自选择性的优点。化学镀甚至可以分别在硅衬底、钨衬底和氮化钛衬底上制备出直径小于50纳米的镍插塞电极。用能量色散X射线微量分析仪（EDXM）测定出用化学镀在硅衬底上制备出的纳米尺度插塞电极的主要成分是镍。最后,采用化学镀方法,制备了直径为9微米的插塞电极的垂直结构相变存储器器件。通过研究器件的电流-电压特性表明,化学镀方法可以满足器件应用要求。因此,用简单、低成本的化学镀方法来制备纳米尺度金属插塞电极,对器件的应用有重要意义。     

贵金属纳米颗粒/石墨烯复合基底SERS研究进展

由于贵金属纳米颗粒/石墨烯复合基底可为喇曼光谱分析技术提供灵敏度高、稳定性好、生物相容性好的基底而备受关注。首先从电磁原理和化学原理两个角度出发,系统地探讨了贵金属纳米颗粒/石墨烯复合基底表面增强喇曼散射(SERS)的机理,进而概述了石墨烯及贵金属纳米颗粒的制备方法及其性能特征,并详细介绍了化学气相沉积法制备石墨烯和物理法制备贵金属纳米颗粒的过程。在此基础上,对不同贵金属纳米颗粒/石墨烯复合基底SERS的国内外研究进展进行了综合的阐述和分析,主要介绍了贵金属Ag,Au和Pt的纳米颗粒复合体系,最后对贵金属纳米颗粒/石墨烯复合基底SERS技术在各个领域的应用及其发展前景进行了展望。     

Stretchable Supercapacitor with Adjustable Volumetric Capacitance Based on 3D Interdigital Electrodes

Reduced graphene oxide (rGO)‐based materials have shown good performance as electrodes in flexible energy storage devices owing to their physical properties, high specific surface area, and excellent electrical conductivity. Here, a novel road is reported for fabricating high‐performance supercapacitors based on 3D rGO electrodes and solid electrolyte multilayers via pressure spray printing and machine coating. These supercapacitors demonstrate high and adjustable volumetric capacitance, excellent flexibility, and stretchability. The results show that this commercial strategy has its essential merits such as low‐cost, inexpensive, and simple fabrication for large area production. These properties are in the favor of fabricating high‐performance supercapacitor to meet the practical energy demands in devices, especially flexible electronic devices. Furthermore, this novel 3D interdigital electrode concept can be widely applied to other energy devices for enhancing performances and to other micro devices for reducing cost.     

Reversible Switching Phenomenon in Diarylethene Molecular Devices with Reduced Graphene Oxide Electrodes on Flexible Substrates

Photoswitching molecular electronic devices with reduced graphene oxide (rGO) top electrodes on flexible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly‐(3,4‐ethylenedioxythiophene) stabilized with poly‐(4‐styrenesulfonic acid)/Au top electrodes can hold two stable electrical conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices change their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stresses (bending radius down to 5 mm and bending cycle over 10⁴).     

Systematic Doping Control of CVD Graphene Transistors with Functionalized Aromatic Self‐Assembled Monolayers

Recent reports have shown that self‐assembled monolayers (SAMs) can induce doping effects in graphene transistors. However, a lack of understanding persists surrounding the quantitative relationship between SAM molecular design and its effects on graphene. In order to facilitate the fabrication of next‐generation graphene‐based devices it is important to reliably and predictably control the properties of graphene without negatively impacting its intrinsic high performance. In this study, SAMs with varying dipole magnitudes/directions are utilized and these values are directly correlated to changes in performance seen in graphene transistors. It is found that, by knowing the z‐component of the SAM dipole, one can reliably predict the shift in graphene charge neutrality point after taking into account the influence of the metal electrodes (which also play a role in doping graphene). This relationship is verified through density functional theory and comprehensive device studies utilizing atomic force microscopy, X‐ray photoelectron spectroscopy, Raman spectroscopy, and electrical characterization of graphene transistors. It is shown that properties of graphene transistors can be predictably controlled with SAMs when considering the total doping environment. Additionally, it is found that methylthio‐terminated SAMs strongly interact with graphene allowing for a cleaner graphene transfer and enhanced charge mobility.     

A Graphene‐Based Coaxial Fibrous Photofuel Cell Powered by Mine Gas

Flexible photofuel cells (PFCs) have triggered strong scientific interest as promising emerging energy conversion devices for clean power generation due to their potential advantages in low‐cost, simple fabrication, room‐temperature operation, and high conversion efficiency, etc. However, how to enable a PFC with excellent structural flexibility and robustness, and meanwhile with sufficient fuel fed onto electrodes and therefore high power generation remains a significant challenge. Herein, a high‐performance coaxial cable‐shaped PFC device is successfully designed and integrated by employing wet‐spun graphene fiber as the inner cathode, TiO₂ nanoparticle‐intercalated graphene spring as the outer photoanode, and a robust polymer gel coated in‐between as the electrolyte separator. The as‐fabricated fiber‐shaped PFC demonstrates effective adsorption of fuel, essential light penetration, and rapid electron/ion transport. Importantly, the fiber cells are sensitive to methane‐based mine gas under sunlight, exhibiting a photocurrent density nearly three orders of magnitude higher than that in air, and excellent and reliable photovoltaic performance with a maximum power density of 0.04 W cm^?2 at 0.35 V. This work has shed light not only in using cheap mine gas for efficient power generation, but also on new strategies for design and fabrication of high‐performance PFCs in flexible electronic devices.     

An Interface‐Induced Co‐Assembly Approach Towards Ordered Mesoporous Carbon/Graphene Aerogel for High‐Performance Supercapacitors

Hierarchically porous composites with mesoporous carbon wrapping around the macroporous graphene aerogel can combine the advantages of both components and are expected to show excellent performance in electrochemical energy devices. However, the fabrication of such composites is challenging due to the lack of an effective strategy to control the porosity of the mesostructured carbon layers. Here an interface‐induced co‐assembly approach towards hierarchically mesoporous carbon/graphene aerogel composites, possessing interconnected macroporous graphene networks covered by highly ordered mesoporous carbon with a diameter of ≈9.6 nm, is reported. And the orientation of the mesopores (vertical or horizontal to the surface of the composites) can be tuned by the ratio of the components. As the electrodes in supercapacitors, the resulting composites demonstrate outstanding electrochemical performances. More importantly, the synthesis strategy provides an ideal platform for hierarchically porous graphene composites with potential for energy storage and conversion applications.     

Large‐Area Schottky Barrier Transistors Based on Vertically Stacked Graphene–Metal Oxide Heterostructures

The fabrication of all‐transparent flexible vertical Schottky barrier (SB) transistors and logic gates based on graphene–metal oxide–metal heterostructures and ion gel gate dielectrics is demonstrated. The vertical SB transistor structure is formed by (i) vertically sandwiching a solution‐processed indium‐gallium‐zinc‐oxide (IGZO) semiconductor layer between graphene (source) and metallic (drain) electrodes and (ii) employing a separate coplanar gate electrode bridged with a vertical channel through an ion gel. The channel current is modulated by tuning the Schottky barrier height across the graphene–IGZO junction under an applied external gate bias. The ion gel gate dielectric with high specific capacitance enables modulation of the Schottky barrier height at the graphene–IGZO junction over 0.87 eV using a voltage below 2 V. The resulting vertical devices show high current densities (18.9 A cm^?2) and on–off current ratios (>10⁴) at low voltages. The simple structure of the unit transistor enables the successful fabrication of low‐power logic gates based on device assemblies, such as the NOT, NAND, and NOR gates, prepared on a flexible substrate. The facile, large‐area, and room‐temperature deposition of both semiconducting metal oxide and gate insulators integrates with transparent and flexible graphene opens up new opportunities for realizing graphene‐based future electronics.     

Development of Graphene Oxide/Polyaniline Inks for High Performance Flexible Microsupercapacitors via Extrusion Printing

Extrusion printing of interdigitated electrodes for flexible microsupercapacitors (fMSCs) offers an attractive route to the fabrication of flexible devices where cost, scalability, and processability of ink formulations are critical. In this work, highly concentrated, viscous, and water‐dispersible inks are developed based on graphene oxide (GO)/polyaniline (PANi) composite for extrusion printing. The optimized GO/PANi‐based all‐solid‐state symmetric fMSCs obtained by extrusion printing interdigitated microelectrodes can deliver outstanding areal capacitance of 153.6 mF cm^?2 and volumetric capacitance of 19.2 F cm^?3 at 5 mV s^?1. It is shown that by fabricating asymmetric fMSCs using the GO/PANi as positive electrode and a graphene‐based negative electrode, the voltage window can be widened from 0.8 to 1.2 V and improvements can be achieved in energy density (from 3.36 to 4.83 mWh cm^?3), power density (from 9.82 to 25.3 W cm^?3), and cycling stability (from 75% to 100% capacitance retention over 5000 cycles) compared with the symmetric counterpart. The simple ink preparation and facile device fabrication protocols reported here make the scalable fabrication of extrusion printed fMSCs a promising technology.     

High‐Performance Dopamine Sensors Based on Whole‐Graphene Solution‐Gated Transistors

Solution‐gated graphene transistors with graphene as both channel and gate electrodes are fabricated for the first time and used as dopamine sensors with the detection limit down to 1 nM, which is three orders of magnitude better than that of conventional electrochemical measurements. The sensing mechanism is attributed to the change of effective gate voltage applied on the transistors induced by the electro‐oxidation of dopamine at the graphene gate electrodes. The interference from glucose, uric acid, and ascorbic acid on the dopamine sensor is characterized. The selectivity of the dopamine sensor is dramatically improved by modifying the gate electrode with a thin Nafion film by solution process. This work paves the way for developing many other biosensors based on the solution‐gated graphene transistors by specifically functionalizing the gate electrodes. Because the devices are mainly made of graphene, they are potentially low cost and ideal for high‐density integration as multifunctional sensor arrays.     

Superelastic and Arbitrary‐Shaped Graphene Aerogels with Sacrificial Skeleton of Melamine Foam for Varied Applications

Elastic graphene aerogels are lightweight and offer excellent and electrical performance, expanding their significance in many applications. Recently, elastic graphene aerogels have been fabricated via various methods. However, for most reported elastic graphene aerogels, the fabrication processes are complicated and the applications are usually limited by the brittle mechanical properties. Thus, it still remains a challenge to explore facile processes for the fabrication of graphene aerogels with low density and high compressibility. Herein, arbitrary‐shaped, superelastic, and durable graphene aerogels are fabricated using melamine foam as sacrificial skeleton. The resulting graphene aerogels possess high elasticity under compressive stress of 0.556 MPa and compressive strain of 95%. Thanks to the superelasticity, high strength, excellent flexibility, outstanding thermal stability, and good electrical conductivity of graphene aerogels, they can be applied in sorbents and pressure/strain sensors. The as‐assembled graphene aerogels can adsorb various organic solvents at 176–513 g g^?1 depending on the solvent type and density. Moreover, both the squeezing and combustion methods can be adopted for reusing the graphene aerogels. Finally, the graphene aerogels exhibit stable and sensitive current responses, making them the ideal candidates for applications as multifunctional pressure/strain sensors such as wearable devices.     

High-Conductivity–Dispersibility Graphene Made by Catalytic Exfoliation of Graphite for Lithium-Ion Battery

Despite the progress made on the production of graphene using liquid-phase exfoliation methods, the fabrication of graphene with both high conductivity and dispersibility remains challenging. Through catalytic exfoliation of graphite, an effective synthesis method for graphene with large lateral size (≈10 µm), high conductivity (926 S cm^–1), and excellent water solubility (≈10 mg mL^–1) is reported herein. Such graphene can be used broadly for applications such as lithium ion batteries, where both high conductivity and dispersibility are required. As an example, the synthesis of graphene and lithium-iron-phosphate composites is demonstrated, which leads to electrodes with dramatically improved cycling stability and rate performance. Adaption of such material leads to electrodes with volumetric energy density as high as 658.7 and 287.6 W h L^–1 under 0.5 and 20 C, respectively, which is significantly higher than that of commercial LiFePO₄ (394.7 and 13.5 W h L^–1 at 0.5 and 20 C, respectively). This work provides a new method of making high-conductivity–dispersibility graphene for various applications.