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).     

A Fully Transparent and Flexible Ultraviolet–Visible Photodetector Based on Controlled Electrospun ZnO‐CdO Heterojunction Nanofiber Arrays

It is essential for novel photodetectors to show good photoresponses, high stability, and have facile fabrication methods. Herein, an optimized electrospinning method to fabricate a photodetector based on nanowire arrays that has a wide spectral response range is demonstrated. Arrays of ZnO‐CdO hybrid nanowires are carefully fabricated fusing ZnO and CdO portions into the same nanowires and subsequently assembling those nanowires into a regular structure. Compared to pure ZnO or CdO nanowire arrays, the hybrid arrays show comparable photocurrent/dark current ratios and response speeds, but they possess a much wider spectral response range from ultraviolet to visible light. The optoelectronic and electronic properties of the ZnO‐CdO hybrid nanowire arrays are systematically explored. Based on this, a transparent and flexible photodetector made of ZnO‐CdO hybrid nanowire arrays is fabricated. It shows a high transparency of around 95% in the spectral range of 400–800 nm and maintains its properties even after 200 bending cycles. Importantly, the developed, simple method can be directly applied to many types of substrates and a transfer of the nanowires becomes unnecessary, which guarantees a high quality of the devices.     

Highly Flexible Transparent Electrodes Containing Ultrathin Silver for Efficient Polymer Solar Cells

Transparent electrodes (TEs) having electrooptical trade‐offs better than state‐of‐the‐art indium tin oxide (ITO) are continuously sought as they are essential to enable flexible electronic and optoelectronic devices. In this work, a TiO₂‐Ag‐ITO (TAI)‐based TE is introduced and its use is demonstrated in an inverted polymer solar cell (I‐PSCs). Thanks to the favorable nucleation and wetting conditions provided by the TiO₂, the ultrathin silver film percolates and becomes continuous with high smoothness at very low thicknesses (3–4 nm), much lower than those required when it is directly deposited on a plastic or glass substrate. Compared to conventional ITO‐TE, the proposed TAI‐TE exhibits exceptionally lower electrical sheet resistance (6.2 Ω sq^?1), higher optical transmittance, a figure‐of‐merit two times larger, and mechanical flexibility, the latter confirmed by the fact that the resistance increases only 6.6% after 10³ tensile bending cycles. The I‐PSCs incorporating the TAI‐TE show record power conversion efficiency (8.34%), maintained at 96% even after 400 bending cycles.     

具有Parylene 涂层的WLAN 平面柔性天线*

设计了一种用于无线局域网(WLAN)的平面柔性天线。该天线的设计采用厚度为127μm 的聚酰亚 胺薄膜作为天线的印制板,利用电容加载的单极子天线结构,使其获得了柔性和双频宽带的性能。整个天线被 10μm 厚度的Parylene-C 保护涂层所覆盖,使天线具备了良好的防潮、防水等性能。对天线在平面和各种弯曲状态下 的性能进行了测试,测试结果表明,该天线在工作频带内的回波损耗优于10dB,具有较好的全向辐射特性,实验结果 表明该天线可以应用于柔性通信设备中。     

Metal‐Organic Framework Nanofilm for Mechanically Flexible Information Storage Applications

Metal‐organic frameworks (MOFs), which are formed by association of metal cations or clusters of cations (“nodes”) with soft organic bridging ligands (“linkers”), are a fascinating class of flexible crystalline hybrid materials offering potential strategy for the construction of flexible electronics. In this study, a high‐quality MOF nanofilm, HKUST‐1, on flexible gold‐coated polyethylene terephthalate substrates is fabricated using liquid phase epitaxy approach. Uniform and reproducible resistive switching effect, which can be sustained under the strain of as high as 2.8%, and over the wide temperature range of –70 to +70 °C, is observed for the first time in the all solid‐state Au/HKUST‐1/Au/thin film structures. Through conductive atomic force microscopic and depth‐profiling X‐ray photoelectron spectroscopicanalysis, it is proposed that the electric field‐induced migration of the Cu_­²⁺ ions, which may lead to subsequent pyrolysis of the trimesic acid linkers and thus the formation of highly conducting filaments, could be the possible origin for the observed uniform resistance switching in HKUST‐1 nanofilms.     

基于滑模变结构的柔性倒立摆控制研究

针对柔性倒立摆稳摆控制比较困难且传统指数趋近率的滑模变结构控制易对系统造成抖振,基于机理建模方法建立柔性倒立摆数学模型,提出变指数趋近率的滑模变结构控制方法,设计了滑模变结构控制器,使系统具有较好的稳摆控制和鲁棒性。仿真结果表明,基于变指数趋近率的滑模变结构控制方法能够更好的实现倒立摆稳定控制,相比于传统指数趋近率的滑模控制器输出更加平滑,进而减小了控制器的负担。     

基于无网格点插值法的旋转悬臂梁的动力学分析

将基于多项式点插值的无网格方法用于旋转悬臂梁的动力学分析. 利用无网格点插值方法对柔性梁的变形场进行离散, 考虑梁的纵向拉伸变形和横向弯曲变形, 并计入横向弯曲变形引起的纵向缩短, 即非线性耦合项, 运用第二类Lagrange方程推导得到系统刚柔耦合动力学方程. 与有限元法相比, 该方法只需节点信息, 无需定义单元, 具有前处理简单的优势; 构造的形函数采用更多的节点插值, 具有高阶连续性. 将无网格点插值方法的仿真结果与有限元和假设模态法进行比较分析, 验证了该方法的正确性, 并表明其作为一种柔性体离散方法在刚柔耦合多体系统动力学的研究中具有可推广性.     

还原石墨烯氧化物-银纳米线柔性复合电极的制备与性能研究

制备了一种具有高导电性、高透过率以及良好的柔性和机械稳定性的还原石墨烯氧化物(RGO)-银纳米线(AgNW)复合电极.将低浓度的AgNW旋涂在制备的RGO薄膜上,使AgNW搭接在RGO的晶界、褶皱处,提高了RGO薄膜的载流子迁移能力.在保证透过率的前提下,提高复合薄膜的导电性能.结合薄膜转写工艺,制备了电阻为420 Ω/口且透过率达62％的RGO-AgNW柔性复合电极.该复合电极具有良好的柔性以及机械稳定性,随着弯折次数的增加,电阻没有明显变化.     

Fabrication of transparent and flexible carbon‐doped ZnO field emission display on plastic substrate

Transparent and flexible carbon doped ZnO (C:ZnO) field emission device was successfully fabricated on an arylite substrate. Excellent adhesion of deposited C:ZnO on the flexible substrate was achieved with low sputtering power and Ar flow rate. In the fabricated device, nanostructured C:ZnO and as‐deposited thin films were used as field emitter and phosphor screen, respectively. The C:ZnO thin film showed a transparency of about 80% at 550 nm wavelength and average sheet resistance of 1.96 kΩ/□. The C:ZnO phosphor screen emitted red light during the field emission measurement, correlating the dominant cathodoluminescence peak at 646 nm. Thus, a promising transparent and flexible field emission display can be realized with C:ZnO based material.

Transparent and flexible C:ZnO film phosphor screen (anode) and nanocone emitters (cathode) for field emission device.