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.     

Novel viologen derivatives for electrochromic ion gels showing a green-colored state with improved stability

We successfully synthesized a novel viologen derivative (1,1′-bis(3-fluoro-4-(trifluoromethyl)phenyl)-4,4′-bipyridinium bis(trifluoromethylsulfonyl)imide, TFMFPhV(TFSI)₂) exhibiting a green-colored state. We selected cyanophenyl viologen (CNPhV²⁺), a conventional electrochromic (EC) chromophore with a green color indication, to compare EC performance. Ion gels consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) were employed as a solid-state electrolyte for EC devices (ECDs). In comparison to CNPhV²⁺-containing devices, the ECDs with TFMFPhV²⁺ showed higher transmittance contrast, larger coloration efficiency, faster coloration and bleaching responses, and better coloration/bleaching operational stability. Cyclic voltammetry revealed that the more stable redox behavior of TFMFPhV²⁺ is the origin of the outstanding ECD performance.     

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.     

Novel electrochromic and infrared emissivity modulation films based on poly(carbazoyltriphenylamine) and poly(carbazoyltriphenylamine-thiophene)

Synthesis and characterizations of novel conducting polymer film based on poly(carbazoyltriphenylamine) (poly(CBZ-TPA)) were studied. Additionally, copolymer film based on CBZ-TPA and thiophene (Th) was also obtained by electrochemical polymerization. Electrochromic properties of poly(CBZ-TPA) and poly(CBZ-TPA-Th) films were investigated by cyclic voltammetry and double step potential chronoamperometry. Optical properties of the two films were characterized by UV–vis spectrophotometer and FT-IR spectrometer. Different colors of poly(CBZ-TPA) film were achieved, which exhibits as camel gray (at −0.5 V), light gray (at 0 V) and army green (at 1.6 V). The maximum UV–vis absorption difference of poly(CBZ-TPA) film is about 15.83% in the visible region when applied with the voltage between 0 V and 1.6 V, and the coloring and bleaching time are 1.8 s and 1.0 s, respectively. The biggest different average IR-emissivity modulation of poly(CBZ-TPA) film is 0.37 in the wavelength regions of 8–14 μm. The copolymerization film of thiophene with CBZ-TPA has a distinct effect on the electrochromic performance of poly(CBZ-TPA) film. Compared with poly(CBZ-TPA) film, poly(CBZ-TPA-Th) film shows different colors, which exhibits as maize-yellow (at −0.5 V), milk white (at 0 V) and dark green (at 1.4 V). The maximum UV–vis absorption difference of poly(CBZ-TPA-Th) film is about 23.30% in the visible region between 0 V and 1.4 V, but it has a slower response speed (coloring and bleaching time are 3.0 s and 4.0 s, respectively). However, the biggest different average IR-emissivity modulation of poly(CBZ-TPA-Th) film reaches up to 0.41 in the wavelength regions of 8–14 μm compared to that of poly(CBZ-TPA) film.     

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.     

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>...     

Thiophene-2,5-diesters as electrochromic materials: The effect of ester groups on the device performance and stability

A series of thiophene-2,5-dicarboxylic acid diesters (R–Th, compounds 3–9) with linear and branched alkyl (3–7) and benzyl (8,9) ester groups have been synthesized and characterized by ¹H/¹³C NMR and MS. Their electrochemical reduction in cyclic voltammetry experiments proceed as two-step single-electron transfer process to form radical anions R–Th^•– (at −1.87 … −2.00 V vs Ag/Ag⁺) and dianions R–Th^2– (at −2.48 … −2.68 V vs Ag/Ag⁺). In spectroelectrochemical experiments in Bu₄NClO₄/N,N-dimethylformamide electrolyte solution, all compounds exhibit reversible color changes from colorless in their neutral state to blue colors in the reduced state, with two characteristic absorptions of radical anions R–Th^•– in the short-wavelength (ca. 406–420 nm) and long-wavelength regions (ca. 610–655 nm). The L*a*b* CIE color coordinates of th e sandwich-type electrochromic devices have been evaluated by colorimetry measurements and the devices demonstrated good coloration efficiency of up to 512 cm² C⁻¹. The cycling stability of the materials on electrochromic coloring/bleaching substantially depends on the structure of the R ester groups and increased with increasing the steric hindrances in the R. In the series of seven studies compounds, the best cycling stability was observed for R = 2-ethylhexyl and benzyl. The degradation mechanism during electrochromic cycling in an inert atmosphere (under nitrogen) and in air is discussed.     

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.     

A dual electrochromic film based on nanocomposite of aniline and o-toluidine copolymer with tungsten oxide nanoparticles

A dual electrochromic (EC) film was prepared based on composite of tungsten oxide nanoparticles and copolymer of aniline and o-toluidine, by electrochemical polymerization method. In this method, aniline and o-toluidine monomers were dispersed in the solution containing tungsten oxide (WO₃) nanoparticles and the final mixture was used for electrodeposition of film on fluorine doped tin oxide (FTO) coated glass. WO₃ nanoparticles were incorporated in the copolymer matrix structure, and a dual EC film was constructed. EC properties of WO₃, copolymer and WO₃-copolymer nanocomposite films were evaluated by cyclic voltammetry (CV) and the UV–Vis spectrophotometry. Also, the optical response and coloration efficiency (CE) of samples were investigated. The composition of organic-inorganic EC materials have improved properties in application of the EC film such as significant optical modulation (37.35% at 633 nm) and high switching speed and high coloration efficiency (116.6 cm² C⁻¹ at 633 nm). These achievements were better than WO₃ or copolymer films. The improved EC properties were appertained to the mixture of prominences of both materials.     

Effects of substitution position on electrochemical,electrochromic, optical,and photoresponsive properties of azobenzenecarboxylic acid alkyl ester derivatives

This study aimed to investigate the effects of substitution position on the electrochemical, electrochromic, optical, and photoresponsive properties of azobenzenecarboxylic acid alkyl ester derivatives. Therefore, a series of azobenzenen ester derivatives, including azobenzene-4,4′-dicarboxylic acid dialkyl ester derivatives (ADDEDs), azobenzene-3,3′-dicarboxylic acid dialkyl ester derivatives (ADADEs), and azobenzene-3,3′,5,5′-tetracarboxylic acid four alkyl ester derivatives (ATFAEDs), was synthesized in this work, and their electrochemical, electrochromic, optical, and photoresponsive properties were characterized. Substitution position significantly influenced the electrochemical, electrochromic, and optical properties but not the photoresponsive properties of azobenzenecarboxylic acid alkyl ester derivatives. With regard to stability and response time, the electrochromic properties of azobenzenecarboxylic acid alkyl ester derivatives decreased in the following order: ADDEDs > ATFAEDs > ADADEs. However, ADDEDs, ADADEs, and ATFAEDs can all be reversibly and efficiently photoswitched between trans and cis states upon alternate irradiation at 365 and 440 nm under electrochromic conditions.     

基于几何规划的模拟器件建模与电路性能优化

基于分段线性函数,提出一种新的对模拟器件进行建模的方法,并提出乐观、悲观两种数据拟合算法,两种算法均能较好地拟合MOS管参数。模型建立之后,利用几何规划对电路性能进行优化。乐观算法会得到较好的电路性能,但可能不满足约束条件;悲观算法能够严格满足约束条件,但是得到的电路性能未必最优。在此基础上,提出一种基于响应曲面方法的折衷优化算法,能够得到综合考虑电路性能和约束条件的电路设计参数。最后,以两级放大器为优化实例,证明该方法的有效性。     

微镜阵列激光成像技术及其性能分析

提出了一种激光三维成像技术,该方法以推扫方式工作,采用数字微镜器件(Digital Mirror Device,DMD)来进行激光回波脉冲飞行时间(Time of Flight,TOF)的空间转换。由于目标上不同距离点回波脉冲的飞行时间不同,当脉冲到达时微透镜阵列将从一个状态转换到另一个状态,在接收端传感器焦平面上显示不同相对位置的条纹,利用条纹相对距离可以重建目标的剖面轮廓距离像。相比于其他三维成像技术,该技术具有成像速率高、探测视场角大、结构简单、体积小易于集成化等优点。     

基于ARM的嵌入式汽车检测装置的设计与实现

结合基于ARM的嵌入式汽车安全性能检测装置的设计，对整个嵌入式系统开发过程，包括硬件平台，操作系统的选择，开发环境与开发工具以及软／硬件的协同设计方法进行了探讨。     

高效率磷光与荧光相结合的白色有机发光器件

制作了一种白色有机电致发光器件(WOLED)。将红光[Ir(piq)2(acac)]及绿光[Ir(ppy)3]磷光掺杂染料分别掺入到母体CBP中,在2种磷光发光层间插入蓝光材料DPVBi,引入电子传输能力强的BPhen作为电子注入层和空穴阻挡层,通过改变蓝光发光层的厚度,得到了高效率的WOLED,最大电流效率可达17.6cd/A,最大功率效率达13.7lm/W,最大亮度达27525cd/m2,当电压从4V变化到12V时,色坐标从(0.54,0.35)变化到(0.30,0.31),基本处于白光区。器件的特点在于DPVBi的存在阻挡了2种磷光材料间的能量转移,色度可以通过简单地调整DPVBi的厚度,避免使用稀有的蓝光磷光材料和与其相匹配的母体材料,同时又可以保持较高的发光效率。     

Solution-processable star-shaped photovoltaic organic molecules based on triphenylamine and benzothiadiazole with longer pi-bridge

Two solution-processable star-shaped D-π-A organic molecules with triphenylamine (TPA) as donor unit, benzothiadiazole (BT) as acceptor unit and 4-hexyl-thienylenevinylene as pi conjugated bridge, S(TPA-TBTT) and S(TPA-TBTT-TPA), have been designed and synthesized for the application as donor materials in bulk-heterojunction organic solar cells (OSCs). The two molecules possess broader absorption from 350 to 700 nm benefitted from the longer pi-bridge in the molecules but weaker absorbance and poorer solubility in comparison with their corresponding organic molecules with shorter vinylene pi-bridge. The OSC based on S(TPA-TBTT): PC₇₀BM (1:3, w/w) exhibited J_sc of 6.41 mA/cm², V_oc of 0.75 V, FF of 39.0% and power conversion efficiency of 1.90%, under the illumination of AM 1.5, 100 mW/cm².     

基于单片机的智能化多媒体电脑遥控装置的设计

为了解决无法远离计算机多媒体设备进行操作的现象。本文提出一种基于STC89C51单片机控制的智能化多媒体电脑遥控装置的设计。在设计中结合红外遥控器、红外接收电路、串口转USB模块,有效地克服了其不足问题。结果表明,该装置能够自动识别遥控信号并解码,可以智能学习自定义按键功能,利用身边任意一款遥控器结合本装置就可以脱离计算机有线的束缚,使用灵活,操作简便,性价比极高,可广泛应用于教室、会议室、家庭、娱乐等场合。     

基于硅基微结构高性能太赫兹波电控调制器

通过硅基微结构与二氧化钒(VO2)相变薄膜相结合,设计并实现了一种电控太赫兹幅度调制器件。该调制器具有很高的太赫兹波透射率与极低的器件插损,同时具有大的工作带宽和调制深度。仿真和实验测试结果表明,该调制器对太赫兹波的增透响应带宽为0.25~0.95 THz波段。在0.4~0.85 THz频段内(约450 GHz宽带)的透射率超过80%,相较于硅衬底的透射率增加了10%以上,且透射率最高可达85%。对该器件电调控后,调制深度可达76%以上,器件透射率变化幅度可达65%。因低插损、大调制幅度以及宽工作带宽,该太赫兹调制器在太赫兹成像和通信系统中具有重要的应用价值。     

Efficient and economical dye-sensitized solar cells based on graphene/TiO2 nanocomposite as a photoanode and graphene as a Pt-free catalyst for counter electrode

Dye-sensitized solar cells have been fabricated by employing graphene/TiO₂ nanocomposites as photoanodes and graphene as a counter electrode. The mixing technique is used to prepare graphene/TiO₂ nanocomposites. The dispersion of graphene in TiO₂ is affirmed by transmission electron microscopy analysis. X-ray photoelectron spectroscopy is carried out to confirm the interstitial incorporation of carbon atoms in the TiO₂ matrix through O TiC and TiOC surface states. The electrochemical activity and stability of graphene as a catalyst for counter electrode are investigated by cyclic voltammetry and chronoamperometry measurements. Solar cells fabricated are characterized by photocurrent–voltage characteristic, Incident photon-to-current efficiency, and electrochemical impedance spectroscopy analyses. The solar cell assembled with 0.08%GR-TiO₂/N3/GR shows power conversion efficiency of 7.70%. This efficiency is superior to that of TiO₂/N3/Pt based solar cell (7.28%). The improvement in efficiency can be attributed to a fast electron transport, improved light harvesting efficiency, and enhanced electron collection at photoanodes.     

基于射频传输的多媒体教学辅助装置研究设计

采用射频无线数据传输技术、USB接口技术、加速度传感技术以及PCM编码压缩技术,研究并设计了由手持端和接收端两部分构成的多媒体教学辅助装置。手持端具有无线话筒和鼠标左、右键功能,并利用教师手势和摇杆来实现操作屏幕光标的移动,采集到的声音数据和操作指令通过射频无线传送给接收端;接收端通过USB接口将数据和指令上传到PC机,驱动课堂多媒体设备来实现声音播放、课件演示以及教学软件操作,从而实现教师在课堂范围内远距离操作多媒体设备进行教学的功能。     

High efficiency OLEDs based on anthracene derivatives: The impact of electron donating and withdrawing group on the performance of OLED

New well-defined bulky anthracene derivatives with side groups having electron donating or withdrawing properties 8a-d were synthesized. The compounds contain substituted anthracene as the central core attaching 2-(4-(2-pyridinyl)- phenyl)vinyl and 4-R-phenyl [R: H (a), OMe (b) and CF₃ (c), N(Ph)₂ (d)] groups at 9- and 10- positions. The impact of electron donating, withdrawing and neutral groups and their influence on the molecules photophysical, charge transfer (CT), triplet transfer (TT) and triplet–triplet annihilation (TTA) properties has been investigated. Based on the photophysical studies the most promising molecule (8d) has been selected and high efficiency fluorescent OLEDs with EQE at very low current efficiency reaching 7% were obtained. The value at low current density implies a Triplet Fusion (TF) contribution of 45%, very close to the maximum theoretical value of 50% when only the singlet decay channel is open to TTA, however we believe that in this case both TTA and TADF contribute to the triplet harvesting to yield high EQE values, and this mixed triplet harvesting arises through the heterogeneity of the films. At high current density a brightness of 20000 cd/m² was achieved and it is assigned partially to the material crystallisation.