碳纳米管薄膜的制备及其在柔性电子器件中的应用

近年来,柔性电子器件的发展日新月异。以碳纳米管为代表的碳纳米材料,尤其是其组装成的宏观结构碳纳米管薄膜具有良好的柔性和优异的导电性,且具有化学稳定、热稳定、光学透明性等优点,在柔性电子领域展现了极大的应用潜力。本文简要综述了近年来碳纳米管薄膜在柔性电子器件领域的研究进展。首先详细介绍了碳纳米管薄膜的两类主要制备方法,分别为干法制备和湿法制备;继而介绍了碳纳米管薄膜在多种柔性电子器件的组装、性能与应用方面的最新研究进展;最后总结了碳纳米管薄膜基柔性电子领域的发展现状,并讨论了该领域所面临的挑战及其未来前景。     

Fabrication of flexible light shutter using liquid crystals with polymer structure

We fabricated a light shutter using plastic substrates for high visibility of a flexible see-through display. To achieve a flexible light shutter using liquid crystals (LC), it is essential to maintain the cell gap when the light shutter is bent. We studied methods to fabricate flexible LC light shutters using plastic substrates. We demonstrated light shutters that are initially transparent and flexible with or without polymer walls. We have elucidated that polymer walls and networks provide mechanical stability against the bending of an LC light shutter without any degradation in the electro-optic characteristics. We predict that a flexible light shutter provides not only high visibility but also mechanical stability to a flexible see-through display by positioning it at the back of a flexible see-through display panel.     

柔性硅纳米线阵列的制备及光催化性能研究

硅纳米线阵列是利用太阳能解决能源和环境问题的重要材料,然而,可用于柔性器件和生物相容性器件的柔性硅纳米线阵列的制备方法非常有限。本文通过化学气相沉积,以及高分子转移的方法,成功制备了具有不同高分子层厚度的柔性硅纳米线阵列,并研究了高分子层厚度对柔性硅纳米线阵列光催化性能的影响。结果表明,高分子层厚度越小,柔性硅纳米线阵列的光催化性能越强。因此,利用本文提出的制备方法得到的高分子层厚度低至5 μm的柔性硅纳米线阵列,具有作为高效柔性太阳能电池和全光解水系统光电极的潜力。同时,该研究结果也为设计具有高效光能转换能力的柔性纳米线阵列提供了重要依据。     

Structural design and impact resistance of three-dimensional structure-reinforced flexible polymer composites

Three-dimensional (3D) structure-reinforced flexible polymer composites have great potential as personal protective materials. These composites exhibit excellent mechanical properties and failure mechanisms than typical rigid composites because of the complex dynamic reaction processes caused by the 3D structure in response to impact. This paper comprehensively reviews the impact resistance mechanism of 3D structure-reinforced flexible polymer composites by combining current results with relevant investigations. 3D woven fabric reinforcements and flexible matrix materials of flexible polymer composites systems are presented in this paper. The classification for 3D woven fabric reinforcements is reviewed, as well as the effect of reinforcement structures on the impact resistance of the flexible composites. Furthermore, several flexible matrix are introduced. Several external factors affecting the impact resistance of composites are then discussed. Finally, the impact damage mechanism of 3D structure-reinforced flexible polymer composites is summarized and analyzed.     

Shape-specific detection based on fluorescence resonance energy transfer using a flexible water-soluble conjugated polymer

We present the detection of the shape-specific conformation of DNA based on the fluorescence resonance energy transfer (FRET) by using a novel flexible water-soluble cationic conjugated polymer (CCP). The flexible backbone of CCP has more conformational freedom with the potential to be responsive to analyte shape by electrostatic interaction between flexible CCP and negatively charged DNA. The analyte shape dependent recognition is accomplished by structural changes that compressed or extended the flexible CCP. The morphology-dependent spectral properties of the novel flexible polymer related to the analyte shapes are investigated in detail, where two types of chromophores, referred to as "isolated" segment and "packed" segment aggregates, within the flexible polymer are identified by means of ensemble and single molecule measurements upon binding with different geometric DNA. The change in fluorescence intensity upon binding with shape-specific DNA without obvious color shifts makes this novel flexible polymer a suitable CCP donor for FRET measurements. The results provide insights for understanding the spectral properties of flexible water-soluble CCP and CCP/DNA interaction related to the geometry of target analyte.     

Free energy calculations using flexible-constrained, hard-constrained and non-constrained molecular dynamics simulations.

A comparison of different treatments of bond-stretching interactions in molecular dynamics simulation is presented. Relative free energies from simulations using rigid bonds maintained with the SHAKE algorithm, using partially rigid bonds maintained with a recently introduced flexible constraints algorithm, and using fully flexible bonds are compared in a multi-configurational thermodynamic integration calculation of changing liquid water into liquid methanol. The formula for the free energy change due to a changing flexible constraint in a flexible constraint simulation is derived. To allow for a more direct comparison between these three methods, three different pairs of models for water and methanol were used: a flexible model (simulated without constraints and with flexible constraints), a rigid model (simulated with standard hard constraints), and an alternative flexible model (simulated with flexible constraints and standard hard constraints) in which the ideal or constrained bond lengths correspond to the average bond lengths obtained from a short simulation of the unconstrained flexible model. The particular treatment of the bonds induces differences of up to 2 % in the liquid densities, whereas (excess) free energy differences of up to 5.7 (4.3) kJ mol(-1) are observed. These values are smaller than the differences observed between the three different pairs of methanol/water models: up to 5 % in density and up to 8.5 kJ mol(-1) in (excess) free energy.     

纳米碳材料在可穿戴柔性导电材料中的应用研究进展

可穿戴设备的兴起使得对柔性器件的需求日益提高,柔性导电材料作为可穿戴器件的重要组成部分而成为研究的热点。传统的电极材料主要是金属,因金属材料本身不具有柔性,一般通过降低金属层厚度以及设计波纹结构等策略实现其在柔性器件中的应用,其加工程序复杂,成本较高。以碳纳米管和石墨烯为代表的纳米碳材料兼具良好的柔性和优异的导电性,且具有化学稳定、热稳定、光学透明性等优点,在柔性导电材料领域展现了极大的应用潜力。本文简要综述了近年来纳米碳材料在柔性导电材料领域的研究进展,首先介绍了碳纳米管基柔性导电材料,分别包括基于碳纳米管水平阵列、碳纳米管垂直阵列、碳纳米管薄膜、碳纳米管纤维的柔性导电材料;继而介绍了石墨烯基柔性导电材料,包括基于剥离法制备的石墨烯和化学气相沉积法制备的石墨烯以及石墨烯纤维基柔性导电材料;并简述了碳纳米管/石墨烯复合柔性导电材料;最后论述了纳米碳材料基柔性导电材料所面临的挑战并展望了其未来发展方向。     

Critical importance of current collector property to the performance of flexible electrochemical power sources

The property of current collector is significant to the performance of flexible power supply.     

可穿戴柔性触觉传感器的研究进展

可穿戴柔性触觉传感器是用来模仿人类触觉的器件, 可以感知人体以及外界环境的运动、 形变和压力等信息, 在智慧医疗和智能机器人等领域具有广泛的应用前景. 近年来, 大量柔性触觉传感器的研究使其性能得到了巨大的提升, 并在很多领域得到了应用. 本文首先简述了柔性触觉传感器的结构和基本性能; 然后重点介绍了具有自愈合、 自驱动以及可视化等新型高性能触觉传感器的研究进展; 接下来讨论了柔性触觉传感器在可穿戴电子技术、 医疗保健以及人机交互界面等方面的应用; 最后展望了柔性触觉传感器未来所面临的机遇与挑战.     

Freestanding Carbon Nanotube Film for Flexible Straplike Lithium/Sulfur Batteries

Flexible lithium/sulfur (Li/S) batteries are promising to meet the emerging power demand for flexible electronic devices. The key challenge for a flexible Li/S battery is to design a cathode with excellent electrochemical performance and mechanical flexibility. In this work, a flexible strap-like Li/S battery based on a S@carbon nanotube/Pt@carbon nanotube hybrid film cathode was designed. It delivers a specific capacity of 1145 mAh g⁻¹ at the first cycle and retains a specific capacity of 822 mAh g⁻¹ after 100 cycles. Moreover, the flexible Li/S battery retains stabile specific capacity and Coulombic efficiency even under severe bending conditions. As a demonstration of practical applications, an LED array is shown stably powered by the flexible Li/S battery under flattened and bent states. We also use the strap-like flexible Li/S battery as a real strap for a watch, which at the same time provides a reliable power supply to the watch.     

Flexible Glass‐based Amperometric Sensors for Hydrogen Peroxide

The development of flexible sensors could enable significant advances in clinical diagnosis, defense, and environmental monitoring. Flexible glass provides the flexibility and possesses stable chemical and physical properties. Here, we show that carbon graphite and silver/silver chloride inks can be printed onto flexible glass to construct amperometric sensors, and the sensors show sensitive and rapid detections of hydrogen peroxide. We anticipate that these results could provide exciting avenues for fundamental studies of flexible electronics and flexible bioelectronics, as well as a variety of applications in fields ranging from medical diagnosis to defense.     

Chemistry Aspects and Designing Strategies of Flexible Materials for High-Performance Flexible Lithium-Ion Batteries

In recent years, flexible and wearable electronics such as smart cards, smart fabrics, bio-sensors, soft robotics, and internet-linked electronics have impacted our lives. In order to meet the requirements of more flexible and adaptable paradigm shifts, wearable products may need to be seamlessly integrated. A great deal of effort has been made in the last two decades to develop flexible lithium-ion batteries (FLIBs). The selection of suitable flexible materials is important for the development of flexible electrolytes self-supported and supported electrodes. This review is focused on the critical discussion of the factors that evaluate the flexibility of the materials and their potential path toward achieving the FLIBs. Following this analysis, we present how to evaluate the flexibility of the battery materials and FLIBs. We describe the chemistry of carbon-based materials, covalent-organic frameworks (COFs), metal-organic frameworks (MOFs), and MXene-based materials and their flexible cell design that represented excellent electrochemical performances during bending. Furthermore, the application of state-of-the-art solid polymer and solid electrolytes to accelerate the development of FLIBs is introduced. Analyzing the contributions and developments of different countries has also been highlighted in the past decade. In addition, the prospects and potential of flexible materials and their engineering are also discussed, providing the roadmap for further developments in this fast-evolving field of FLIB research.     

Recent progress in 2D materials for flexible supercapacitors

High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional (2D) materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure–property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.     

A non-wetting and conductive polyethylene dioxothiophene hole transport layer for scalable and flexible perovskite solar cells

The regulated crystallization of perovskite and highly repeatable preparation are decisive challenges for large-scale flexible perovskite solar cells(PSCs). Herein, we synthesize an oil-soluble poly(3,4-ethylenedioxythiophene)(Oil-PEDOT) as a hole transport layer(HTL). The non-wetting Oil-PEDOT HTL can promote the quality of large-area flexible perovskite films because of its optimized crystallinity and printability. The Oil-PEDOT layer also delivers desirable conductivity and charge transport without a complex doping. Consequently, the flexible PSCs with Oil-PEDOT HTL achieve an efficiency of 19.51% and 16.70%based on 1.05 and 22.50 cm~2, respectively. Moreover, these large-scale flexible PSCs demonstrate remarkable mechanical robustness, and the efficiency exhibits 93% retention after 7,000 bending cycles. These results show that the Oil-PEDOT is a potentially efficient HTL for fabricating efficient large-scale flexible PSCs.     

Two-dimensional Raman study of the submolecular, electric field-induced reorientation of a nematic liquid crystal

Two-dimensional Raman scattering is presented as a technique for the monitoring of electric field-induced, submolecular reorientation in liquid crystals. The motions of the flexible part and the rigid core of 4-pentyl-(4-cyanophenyl)cyclohexane (PCH5) are independently monitored in response to both step and oscillatory electric fields. Step voltage experiments show that the flexible group reorients before the rigid core. Also, oscillatory electric field experiments demonstrate that the flexible and rigid groups reorient asynchronously. In fact, at periodicities that are shorter than the bulk reorientation times, it is observed that the reorientation of the flexible part is amplified, while the motion of the rigid core is inhibited. The data suggest that the flexible group possesses a small, local dielectric anisotropy that can couple with the electric field to induce an independent, cooperative reorientation when the mobility of the rigid core is restricted.     

高分子柔性电极的制备与保护能力测定

应用乙烯基共聚物加导电填料制备可任意改变形状的柔性电极,对电极的电阻进行了测定。并在几种溶液中,以柔性电极为辅助阳极,对碳钢进行外加电流的阴极保护,测定了柔性电极的保护能力。     

Ejection dynamics of semiflexible polymers out of a nanochannel

Using theoretical analysis and three-dimensional Langevin dynamics simulations, we investigate the influence of chain rigidity on the ejection dynamics of polymers from a nanochannel. We find that there exist two distinct dynamical regimes divided by a critical chain length for both flexible and semiflexible chains. At the short chain regime, semiflexible chains eject faster than flexible chains of the same chain length due to the longer occupying length. In contrast, at the long chain regime, semiflexible chains eject slower than flexible ones as the effective entropic driving force decreases. Based on these results, we propose that the nanochannels could be used to separate flexible and semiflexible chains effectively.     

Recent Advances in Flexible Perovskite Solar Cells: Fabrication and Applications

Flexible perovskite solar cells have attracted widespread research effort because of their potential in portable electronics. The efficiency has exceeded 18 % owing to the high‐quality perovskite film achieved by various low‐temperature fabrication methods and matching of the interface and electrode materials. This Review focuses on recent progress in flexible perovskite solar cells concerning low‐temperature fabrication methods to improve the properties of perovskite films, such as full coverage, uniform morphology, and good crystallinity; demonstrated interface layers used in flexible perovskite solar cells, considering key figures‐of‐merit such as high transmittance, high carrier mobility, suitable band gap, and easy fabrication via low‐temperature methods; flexible transparent electrode materials developed to enhance the mechanical stability of the devices; mechanical and long‐term environmental stability; an outlook of flexible perovskite solar cells in portable electronic devices; and perspectives of commercialization for flexible perovskite solar cells based on cost.     

Activated carbon felts with exfoliated graphene nanosheets for flexible all-solid-state supercapacitors

Porous activated carbon felts (ACFs) with exfoliated graphene nanosheets were prepared by a simple thermal treatment strategy. They exhibit high gravimetric and areal specific capacitances as well as long-term cycling stability. Impressively, the all-solid-state supercapacitors based on ACFs electrodes deliver stable electrochemical performance even under different bending states.     

SYNTHESIS AND CHARACTERIZATION OF SOME THERMOTROPIC LIQUID CRYSTALLINE POLYAMIDES

A series of novel mesogenic polyamides containing a flexible pendent side group wassynthesized by solution condensation polymerization. The new monomers, diacids and di-amines containing flexible elements of diferent lengths, were also synthesized and character-ized by ~1HNMR, mass spectroscopy and elemental analysis. The polymers were character-ized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffiactionand polarizing optical microscopy These studies revealed that polyamides containingflexible elements of a sufficient length exhibited thermotropic liquid crystalline(LC) pro-perties. The melting temperatures of this series of polymers were particularly sensitive tothe length of the flexible segment on the main chain and that of the flexible pendent esterside chain. Lyotropic LC behaviours were also observed in solution.