Electrochemical synthesis and electrochromic application of a novel polymer based on carbazole

The compound containing carbazole and thiophene, named as B1 was synthesized with 4-(9H-carbazol-9-yl) phenol and 3,4-dibromo thiophene. Additionally, the electrochemical polymer of B1 was synthesized and coated onto an ITO-glass surface via electrochemical oxidative polymerization. The electrochemical synthesis of the polymer was performed both in 0.05 M LiClO₄ supporting electrolyte in AN/BF₃EtE (1:1, v/v) and an AN/LiClO₄ solvent/electrolyte solution. The compounds were characterized by FT-IR and NMR techniques. The spectroelectrochemical and electrochromic properties of this polymer were also investigated for two electrolyte solution systems. The switching ability of this polymer was measured as the percent transmittance (%T) at its point of maximum contrast. According to the electrochromic measurements, the synthesized polymer had a blue color when it was oxidized, and also when it was reduced, it had a transparent color. Additionally, redox stability measurements indicates that the polymer had a high stability and it could be used to produce new polymeric electrochromic devices and also, it was a good candidate for electrochromic devices (ECDs) applications.     

Both p- and n-type dopable polymer toward electrochromic applications

Synthesis and electrochemical polymerization of 8,11-bis(4-hexylthiophen-2-yl)acenaphtho[1,2-b]quinoxaline (HTAQ) were performed. The polymer was characterized by cyclic voltammetry, UV–Vis-NIR spectroscopy and colorimetry. Cyclic voltammetry studies revealed that the polymer was susceptible to both p- and n-doping. The electroactive polymer has fast switching time and high optical contrast. Spectroelectrochemistry also showed that the polymer is capable of being switched from bluish-green and a highly transmissive green upon p-type doping. Highly fused nitrogen containing acceptor group was utilized in the polymer backbone which was resulted in a polymer that has a significant potential for n-type doping. The existence of a true n-type doping process was proven by the results of both cyclic voltammetry and spectroelectrochemistry studies.     

A new electrochromic copolymer based on dithienylpyrrole and EDOT

A new compound, namely diethyl 2,5-di(thiophen-2-yl)-1H-pyrrole-3,4-dicarboxylate (1), was copolymerized with 3,4-ethylenedioxythiophene (EDOT) via electrochemical method. The copolymer exhibits multicolor electrochromic property: It is found that the copolymer, poly(1-co-EDOT), has a specific optical band gap (1.71 eV) to reflect and/or transmit reddish brown color in the neutral state, and it can be switched to reddish orange, orange, yellowish green and blue colors upon oxidation in a low switching time (1.0 s). Importantly, these colors are essential for camouflage and/or full color electrochromic device/display applications. In addition to these, the obtained copolymer has a coloration efficiency of 173 cm²/C at 500 nm.     

反射型聚苯胺基柔性电致变色器件的研制

采用循环扫描伏安法在Au/Cr/PET复合基底上聚合出聚苯胺(PAN)膜,设计并制备了基于PAN的反射型柔性电致变色器件(ECD)。研究了该ECD反射光谱的电压响应特性。结果显示,所得PAN具有晶体结构,微观上呈直径约60nm的纤维网形态,与Au/Cr/PET基底结合良好;该ECD的反射光谱曲线的波长选择性,在-0.4～+1.8V电压范围内随电压增加而逐渐明显,反射率峰值出现的位置由476nm移至584nm,表现出良好的电致变色响应特性。     

全固态聚苯胺-二氧化钛电致变色器件的制备

以聚苯胺(PANI)为电致变色材料,分别制备了对称结构(SSECD,ITO‖PANI‖解质‖PANI‖lTO)和非对称结构(ASECD,ITO‖PANI‖电解质‖TiO<,2>‖ITO)的全固态电致变色器件.TO<,2>薄膜的制备采用提拉法.经500℃处理后得到锐钛矿结构,所得薄膜由粒径10-20 nm的TiO<,2>...     

聚苯胺基柔性电致变色器件的设计与研制

采用循环扫描伏安法在导电聚酯薄膜上聚合出聚苯胺(PAN)膜,考察了PAN膜的聚合过程及其表现出的电致变色行为;设计并制备了基于PAN膜的反射型柔性电致变色器件,考察了该器件反射光谱的电压响应特性.结果表明,电聚合过程中,在-0.2～2.0V电压范围内,PAN膜的颜色在黄绿-绿-深蓝之间循环变化;在-0.4v～1.8v电压范围内,研制的基于PAN膜的反射型柔性电致变色器件的反射率及其峰值随着外加电压的改变而变化,表现出较好的电压响应特性.     

Highly contrasted and stable electrochromic device based on well-matched viologen and triphenylamine

An electrochromic device (ECD) can change color absorption when subjected to an appropriate voltage. Such a device includes three components: a working electrode, a counter electrode and an electrolyte. Compatibility of these three components is important for ECD’s stability. In this study, two novel compatible electrochromic materials, cathodic 1-(9-hexyl-9H-carbazole)-1′-(propylphosphonic acid)-4,4′-bipyridilium dichloride and anodic (4-(diphenylamino)phenyl)methylphosphonic acid were designed, synthesized and fabricated into electrochromic electrodes using a chemisorption method. We characterized the electrochromic performance of these two electrodes, including the degree of color change, color changing voltage and charge capacity; the results indicated that they matched each other very well. An electrochromic device fabricated using these two electrodes, as expected, exhibited rapid, vivid color changes and proved highly stable for up to 100,000 cycles.     

Design of highly stable and solution-processable electrochromic devices based on PEDOT:PSS

This study aimed to improve the repeatability of electrochromic devices(ECD) based on Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS); therefore, ferrocene was introduced as an anodic species. When 0.05 wt% ferrocene as compared to that of the electrolyte was contained in the electrolyte layer, the bleaching time significantly reduced from 110 s to 25 s without changing ΔT; consequently, repeatability markedly improved. However, ferrocenium cations, generated when ferrocene undergoes a reversible redox reaction, have high reactivity with oxygen, and hence, the stability of ECD is lowered over time. To overcome this problem, l-ascorbic acid, commonly known as vitamin C, was introduced as an antioxidant in the electrolyte layer. The repeatability of the ECD and the storage stability of the electrolyte solution were improved without side effects at an l-ascorbic acid ratio of 0.025 wt% as compared to that of the electrolyte. In addition, using cyclic voltammetry, it was confirmed that l-ascorbic acid did not affect the electrochemical properties of the ECD, and played only the role of an antioxidant for ferrocene. Furthermore, regarding encapsulated ECD, high repeatability could be maintained by preventing solvent evaporation and oxygen penetration into the electrolyte layer. When ECD of size 4 cm × 5 cm was glass encapsulated, there was no change in ΔT even after 5000 cycles for 139 h. We observed day-to-day changes in the response time and ΔT for 30 d; it maintained almost constant values from the beginning. Repeatability tests of 15 cm × 15 cm size large-area ECD for applications, such as smart windows, were conducted.     

Electrochromic properties as a function of electrolyte on the performance of electrochromic devices consisting of a single-layer polymer

Herein, a study on varying salts and their composition used in the gel electrolyte for a one-step lamination assembly procedure for electrochromic devices was carried out to explore their effects on various electrochromic performance parameters, such as color uniformity, photopic contrast, switching speed, and optical memory. Electrochromic polymers formed in different gel electrolyte compositions are highly dependent on the type, amount, and composition of salt used. The following groups of salts were investigated: ionic liquids, ammonium salts, and lithium salts. The lithium salts yielded devices with the best color uniformity, photopic contrast as high as 48%, and switching response speeds as low as 1 s for 5.5 cm² devices using the electroactive monomer 2,2-dimethyl-3,4-propylenedioxythiophene (ProDOT-Me₂) to generate the electrochromic polymer. Hermetically sealed electrochromic devices exhibited optical memory of 27 h for a 2% photopic transmittance loss under normal laboratory conditions, and a 171 cm² electrochromic device was demonstrated.     

Hybrid electrochromic film based on polyaniline and TiO2 nanorods array

Titanium dioxide (TiO₂) nanorods (NRs) array was successfully prepared via hydrothermal method on fluorine doped tinoxide (FTO) coated transparent conductive glass substrate. The hybrid film of polyaniline (PANI)/TiO₂ NRs was achieved through electrochemical polymerization of aniline onto the TiO₂ NRs array film. The electrochromic and optical properties of the hybrid film were investigated by cyclic voltammetry (CV), amperometric i–t and UV–vis spectroscopy. The results indicate that the hybrid film has long term stability and reversible color changes after cyclic voltammetry scans for 200 circles. The PANI/TiO₂ NRs hybrid film can show three different colors. Response time of PANI/TiO₂ NRs hybrid film is about 0.7 s and 2.6 s at different states, respectively. The TiO₂ NRs array and the loose, porous surface among the hybrid film facilitate charge transmission and also provide large surface area for electrochemical reaction.     

Switchable diffractive optics using patterned PEDOT:PSS based electrochromic thin-films

We demonstrate switchable, thin film diffractive optical gratings and Fresnel zone plate lenses fabricated using a micro-patterned electrochromic polymer and gel electrolyte. Electrochemically switching the conductive polymer PEDOT:PSS causes the patterned layer to change between a low-absorption to high absorption state, acting as an amplitude diffractive optical element. The switchable lens and gratings were fabricated using a lithographically patterned electrochromic polymer, a gel electrolyte, and an ITO-coated glass substrate. Within an applied voltage of −1 V to 1 V, the diffraction efficiency of the switchable lens can be varied 4.1-fold between the ‘on’ and ‘off’ states. Due to their low actuation voltage and biocompatibility, electrochemically actuated diffractive optics have potential applications in low power and implantable biomedical devices.     

基于聚合物电介质的并五苯场效应晶体管

采用顶接触结构分别在SiO2、聚甲基丙烯酸甲酯(PMMA)绝缘层上制备了以并五苯为有源层的两种有机场效应晶体管(OFET),其中SiO2绝缘层采用热生长法制备,PMMA绝缘层采用溶液旋涂法制备。与常规基于无机绝缘层的器件相比,采用聚合物为绝缘层后,不但器件的制作工艺简化和成本降低,而且器件性能大幅提高,经测试,器件的迁移率提到0.153cm2/Vs,而阈值电压降低6V。采用原子力显微镜(AFM)、X射线衍射(XRD)等对器件性能提高的原因进行了详细分析。     

聚合物分散型液晶结构紫外光稳定性分析

聚合物分散型液晶组件技术是市面上常用的散射式光开关系统,且常常应用于具隐私保护性之电控切换窗户中。然而对于室外的应用,属于有机高分子材料的液晶材料与聚合物结构对于照射紫外光之稳定性与耐受性值得被讨论,尤其是较少被讨论之高分子聚合物结构的影响。本研究主要探讨不同聚合物结构之聚合物分散型液晶组件在紫外光照射下光电特性的变化,期待可以了解聚合物结构特性随曝光时间的变化并提出适当之改善方法。本实验藉由选择具有高紫外光稳定性之主体液晶搭配紫外固化胶调配聚合物分散型液晶预聚物,分别探讨不同固化胶比例与光强度等固化条件下,组件照射紫外光后对于光电特性造成的影响,以此了解各种聚合物形貌照射紫外光后之光电特性变化。实验结果显示,照射紫外光后,各种聚合物分散型液晶组件之临界电压仅仅些微提升,但下降时间剧烈地提高,以聚合物比例35%、固化强度2mW/cm~2为例,临界电压从15.57V些微提升至18.18V,下降时间从195.12ms大幅提升至925.26ms。此外,本研究亦发现相对于照射前,照射紫外光后之组件的下降时间对于电压施加时间长短相当敏感,且此现象可藉由调整固化光强度与固化胶浓度有抑制之趋势。本研究呈现了各种聚合物分散型液晶组件在照射紫外光后光电特性的变化,并了解聚合物结构的特性变化的影响。     

A new multicolored and near-infrared electrochromic material based on triphenylamine-containing poly(3,4-dithienylpyrrole)

A new compound containing both 3,4-dithienylpyrrole (DTP) and triphenylamine (TPA) groups, namely, 4′-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)-N,N-diphenylbiphenyl-4-amine (DTP-Ph-TPA), was designed and synthesized. The polymer poly-DTP-Ph-TPA (PDTP-Ph-TPA) was prepared by electropolymerization from DTP-Ph-TPA. When the applied potential circulates from 0.0 V to 1.4 V, the polymer not only exhibits reversible multicolor in the visible region (yellow, light green, magenta and blue), but also shows excellent electrochromic properties in the NIR region with high contrast ratio (ΔT = 70.5% in 1550 nm, ΔT = 67.9% in 1310 nm) and a very short response time (about 1.4 s for 1550 nm, 0.9 s for 1310 nm). A single layer electrochromic device (ECD) based on polymer PDTP-Ph-TPA was constructed and characterized.     

Towards the design of ideal electrochromic materials with low driving voltage based on phthalate derivatives

Small molecular organic electrochromic materials have gradually attracted the attention from academia. Although ester organic electrochromic materials show unique advantages such as significant color change, wide color adjustment range and low cost, their electrochromic mechanisms are still unclear, keeping their driving voltage and stability issues unsolved. In this article, the absorption spectra of phthalate derivatives under different conditions are calculated with time-dependent density functional theory to understand the influences on the electrochromic properties by the electronic and steric effects. By the increased conjugation and reduced steric hindrance, carbonyl linking group is found capable to enhance the absorption in the visible region and exhibit low driving voltages. Further, a new electrochromic compound is designed to improve the luminous effect and lower the driving voltage.     

Second-order distributed feedback polymer laser based on holographic polymer dispersed liquid crystal grating

We report on the fabrication and characterization of a second-order distributed feedback (DFB) polymer laser based on a holographic polymer dispersed liquid crystal (HPDLC) transmission grating. The fine organic grating is fabricated on top of the homogeneous conjugated polymer layer in a one-step process. The device shows surface-emitting, single mode laser emission with a threshold of 13.3 μJ/cm², and the working characteristics merely degrade after 10 months of storage in ambient atmosphere. We further explain the dependence of threshold on pumping length, and demonstrate the small refractive index modulation of this all-organic grating is sufficient to maintain efficient DFB laser action. This simple working structure, combined with large processing area provided by the holographic polymerization technique, is extremely promising in realizing ultra-low cost plastic lasers.     

用限制性群盲签名构造电子现金系统

本文提出一个新的称为限制性群盲签名的概念,并且指出了如何利用限制性群盲签名来构造多个银行参与发行的、公正的电子现金系统。一方面,系统保证了发币银行的匿名性,在必要时,可以由中央银行识别出发币银行的身份;另一方面,系统也保证合法用户的匿名性,在特定的情况下,银行在可信方的帮助下,能够撤消用户的匿名性。     

Polarizing polymer solar cells based on the self-organization of a liquid crystalline polymer

We manufactured polarizing polymer solar cells (PSCs) utilizing a liquid crystalline polymer (i.e., poly(2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT)) as an electron donor material and a material that selectively absorbs polarized light. The oriented PBTTT films prepared using a self-organization process exhibited a high dichroic ratio of ca. 6.35 at the absorption peak. The polarizing PSCs based on oriented PBTTT–PC₇₁BM photoactive layers exhibit an anisotropic photovoltaic effect under polarized illumination along the two orthogonal axes. The polarizing PSCs have a larger power conversion efficiency under parallel-polarized illumination than that of isotropic PV devices under unpolarized illumination. Based on picosecond fluorescent spectra, the parallel excitation produces a slower ground state recovery and a longer exciton lifetime than perpendicular excitation for PBTTT molecules in a uniaxially oriented arrangement.     

一种基于MZI的聚合物光波导加速度计

提出了一种基于马赫增德尔干涉仪（MZI）的聚合物光学波导加速度计。理论推导了MZI结构的传输函数,仿真分析了悬臂梁结构参数与器件灵敏度的关系,制备和测试了基于聚合物材料和柔性衬底的加速度传感芯片。制备得到了4 μm×4 μm单模传输芯层波导的传感芯片。搭建了集成光学加速度测试系统,采用比较校准法对探测器输出电压信号进行标定,实现了传感芯片因施加加速度后输出光强变化的测试,完成了加速度测量。该加速度传感芯片分辨率为10-2 g,动态范围为±2 g。