Electrochromic multilayer films of tunable color by combination of copper or iron complex and monolacunary dawson-type polyoxometalate

Electrochromic multilayer films consisting of polyoxometalate (POM) cluster alpha-K(10)[P(2)W(17)O(61)].17H(2)O (P(2)W(17)), copper(II) complex [Cu(II)(phen)(2)](NO(3))(2) (phen = 1,10-phenithroline), and iron complex [Fe(II)(phen)(3)](ClO(4))(2) were fabricated on silicon, quartz and ITO substrates by layer-by-layer self-assembly method. The multilayer films, PSS/Cu(II)(phen)(2)/[(P(2)W(17)/Cu(II)(phen)(2))](n) and PSS/Fe(II)(phen)(3)/[(P(2)W(17)/Fe(II) (phen)(3))](n) were characterized by UV-vis spectra, X-ray photoelectron spectra, cyclic voltammetry (CV), chronoamperometric (CA) and in-situ spectral electrochemical measurements. The interesting feature of the electrochromic film is its adjustable color by reduction of both transition metal complex and polyoxometalate at different potentials. The multilayer films also exhibit high optical contrast, suitable response time and low operation potential due to the presence of mono-lacunary-substituted polyoxometalate and transition metal complex. This is the first example that the color of electrochromic film can be adjustable, which gives valuable information for exploring new electrochromic materials with tunable colors.     

Effects of film structure on electrochromic properties of the multilayer films containing polyoxometalates

Multilayer films of tungstophosphate anion (P₂W₁₈) and poly(allylamine hydrochloride) (PAH) were fabricated on quartz and ITO substrates by layer-by-layer self-assembly method. These films were characterized by UV–vis spectroscopy, cyclic voltammetry (CV), chronoamperometric (CA), chronocoulometry (CC) and atomic force microscopy (AFM). The effects of film structure on multilayer electrochromic properties were investigated. The electrochromic responses of the composite films were related to the surface coverage of anion and multilayer thickness. It was found that higher concentration of polycation and anion, or adding salt to the polycation solution used for multilayer film preparation led to thicker and denser film structure which improved optical contrast and coloration efficiency whereas prolonged response time.     

Near infrared electrochromic variable optical attenuator fabricated by layer-by-layer assembly

An electrochromic variable optical attenuator（ECVOA） was fabricated by layer-by-layer（LBL） assembly of disodium N,N-bis（p-sulfonatophenyl）naphthalenedicarboximide（Naph-SO₃Na） and common cationic polymer poly（diallyldimethylammonium） chloride（PDDA）.The UV-Vis absorption spectra of the multilayer films revealed that approximately an equal amount of Naph-SO₃Na was assembled in each deposition cycle.Upon one-electron reduction, multilayer films exhibited intense absorption around 452 nm and also a broad absorption band from 1200 nm to 1900 nm. Owing to the improved ionic conductivity,the optical attenuation at 1550 nm of the films showed rapid response time and reached 1.3 dB/μm within 5 s.These results indicate that layer-by-layer assembly could be an effective method for the preparation of ECVOA operating in near infrared region.     

Mineralization and osteoblast behavior of multilayered films on TiO2 nanotube surfaces assembled by the layer-by-layer technique

In this paper, the multilayer films of poly-L-lysine (PLL) and DNA were created on TiO₂ nanotube surfaces using the layer-by-layer (LBL) self-assembly technique. Chemical compositions of the assembled multilayered films were investigated by X-ray photoelectron spectroscopy. Biological properties of the multilayered films were evaluated by the biomimetic mineralization and osteoblast cell culture experiments. The results indicated that PLL and DNA were successfully assembled onto TiO₂ nanotube surfaces by electrostatic attraction. Moreover, the samples of assembled PLL or/and DNA had better bioactivity in inducing HA formation and promoting osteoblast cells adhesion, proliferation and early differentiation.     

钒钨酸盐-CdS纳米粒子复合膜的制备与电致变色性能

通过层-层自组装方法制备了由Dawson结构三钒取代型钨酸盐1-K₉P₂W₁₅V₃O₆₂·18H₂O(P₂W₁₅V₃)与CdS纳米粒子构筑的复合膜材料, 研究了CdS纳米粒子添加和复合膜层数对P₂W₁₅V₃多酸复合膜材料电致变色性能的影响. 采用UV, XRD, SEM和循环伏安等测试手段对复合材料的结构和性能进行了表征; 将电化学工作站和紫外-可见吸收光谱联用, 在-1.0~+1.0 V的电压范围内, 对不同层数、 有无CdS纳米粒子复合的的膜材料的电致变色性能进行研究. 研究结果表明, 20层的复合膜材料性能最佳, 光反差为38.05%, 着色时间为3.57 s, 褪色时间为6.94 s, 最大着色效率达到94.04 cm²/C, 实现了从无色、 蓝色到蓝紫色, 再到无色的可逆颜色变化, 相对于单独P₂W₁₅V₃膜, 光反差提高46.07%, 着色效率提高96.53%, 电致变色性能显著提高.     

TiO2-PTPAT纳米核/壳结构复合膜的制备及电致变色性能

通过水热法在氟掺杂氧化锡(FTO)导电玻璃基底上制备了垂直生长的二氧化钛(TiO₂)纳米棒阵列, 以TiO₂纳米棒阵列为模板采用电化学聚合法, 原位制备了TiO₂-聚三[2-(4-噻吩)苯]胺(PTPAT)纳米核/壳结构的复合薄膜, 相比于纯PTPAT薄膜, TiO₂-PTPAT复合薄膜显示出更好的电致变色(EC)性能. PTPAT薄膜在600 nm波长下的对比度为28%, 在1100 nm波长下的对比度为60%, 其褪色时间为3.86 s, 着色时间为5.52 s; TiO₂- PTPAT复合薄膜在600 nm波长下的对比度为43%, 在1100 nm波长下的对比度为79%, 其褪色时间为3.35 s, 着色时间为4.43 s, 表明核/壳复合结构薄膜的光学对比度和响应时间性能更加优异. 将PTPAT薄膜和TiO₂-PTPAT复合薄膜作为电致变色层组装成固态EC器件, 基于复合薄膜的器件具有更好的循环稳定性和更高的耐受电压. 复合薄膜在保持PTPAT薄膜原有的EC性能的基础上, 由于有序生长的纳米阵列结构的引入增加了薄膜的比表面积, 为电致变色过程中离子的掺杂和脱掺杂提供了更多有序通道, 从而加快了离子扩散速度. TiO₂阵列的引入也改善了聚合物薄膜与透明导电电极之间的界面结合情况, 从而提升了器件的稳定性.     

Self assembly and optical properties of dendrimer nanocomposite multilayers

Ultrathin multilayers are important for electrical and optical devices, as well as for immunoassays, artificial organs, and for controlling surface properties. The construction of ultrathin multilayer films by electrostatic layer-by-layer deposition proved to be a popular and successful method to create films with a range of electrical, optical, and biological properties. Dendrimer nanocomposites (DNCs) form highly uniform hybrid (inorganic-organic) nanoparticles with controlled composition and architecture. In this work, the fabrication, characterization, and optical properties of ultrathin dendrimer/poly(styrene sulfonate) (PSS) and silver-DNC/PSS nanocomposite multilayers using layer-by-layer (LbL) electrostatic assembly techniques are described. UV-vis spectra of the multilayers were found to be a combination of electronic transitions of the surface plasmon peaks, and the regular frequency modulations attributable to the multilayered film structure. The modulations appeared as the consequence of the highly regular and non-intermixed multilayer growth as a function of the resulting structure. A simple model to explain the experimental data is presented. Use of DNCs in multilayers results in abrupt, flat, and uniform interfaces.     

新型非线性光学杂化材料结构与性能的研究

由硅烷染料ASD与钛酸四正丁酯在酸性条件下共水解、缩合得到杂化材料,利用透射电镜(TEM)和X射线能量色散谱仪(EDS)进行分析,结果表明,杂化溶胶粒子是由硅和钛的化合物组成的球形纳米粒子.由一维刚性取向气体模型计算杂化材料膜再极化后的二阶非线性光学系数χ⁽²⁾为1.43×10^-7esu.差示扫描量热法(DSC)测得杂化材料的玻璃化温度可达469K;用紫外-可见光谱对杂化膜在极化前后的取向及取向稳定性进行了研究.用原子力显微镜(AFM)和X射线衍射(XRD)研究了材料在极化过程中的结晶行为和微观结构对生色团取向稳定性的影响,初次在这种极化后的膜中观察到了介观结构.     

耦联剂辅助吸附法制备CuInS2量子点敏化太阳电池

分别以CuI 和InAc3 作为铜源和铟源, 十二硫醇(DDT)作为硫源, 采用直接加热法合成不同尺寸的CuInS₂ (CIS)量子点. 运用X射线衍射(XRD), 拉曼光谱(Raman), 高分辨率透射电镜(HRTEM), 紫外-可见(UVVis)吸收光谱表征其相结构、形貌及光学性能. 结果表明: 制备的CIS量子点为黄铜矿结构, 且随着时间的延长, 量子点逐渐长大, 吸收光谱的激子吸收峰逐渐红移, 表现出量子尺寸效应. 采用巯基乙酸为双功能耦联剂辅助吸附法制备CIS敏化的TiO₂薄膜. 通过衰减全反射红外光谱(ATR-FTIR)分析得出, 巯基乙酸上的羧基与TiO₂表面羟基连接, 另一端上的巯基代替长链的DDT与CIS 耦联, 将CIS 成功锚定在TiO₂表面. 该方法不仅操作简单, 而且容易实现CIS在TiO₂表面的吸附. 太阳电池光电性能测试表明, 粒径大小约为3.6 nm的CIS量子点表现出最优的吸附能力以及光电转换性能. 进一步采用连续离子吸附层法对CIS敏化的TiO₂薄膜进行CdS包覆, 光电转换性能大大提高, 其效率达到2.83%, 这主要源于CdS的包覆钝化了CIS 的表面缺陷, 有效地降低了电子复合.     

Label-free Detection of Biotin Using Nanoporous TiO2/DNA Thin-film Coated Wavelength Interrogated Surface Plasmon Resonance Sensors

The sensing sensitivity of the wavelength interrogated surface plasmon resonance（WISPR） biosensor could be improved by self-assembly of nanoporous thin-film of TiO2 nanoparticles/DNA（TiO2/DNA）n（n is the number of bilayer） on wavelength interrogated surface plasmon resonance（WISPR） chips.The growth behavior and surface structure of the nanoporous thin-film were investigated by UV-Vis spectroscopy and scanning electron microscopy,respectively.The home-made WISPR sensor with Krestchmann configuration consisted of a tungsten-halogen lamp as a photon source and a CCD camera as the detector.After the deposition of （DNA/TiO2）n thin film on WISPR chips,the resonance peak of the reflection spectra appeared in air.With the increases of n,the resonance wavelength gradually red shifted,which is consistent with the simulated results.After the optimization of the porous film,the WISPR biosensor was utilized to detect low-molecular-weight analytes,such as biotin.The result demonstrates that the sensitivity of [poly（styrene sulfonate）/polyally lamine hydrochlorides]5（PSS/PAH）5 could be 4 times higher than that of polyelectrolyte multilayer modified WISPR sensor.     

制备二氧化钛分枝纳米棒阵列结构以提高聚合物杂化太阳电池的性能

分别采用一步水热法和两步水热法在导电玻璃(FTO)上制备了二氧化钛(TiO₂)纳米棒(NR)阵列和TiO₂分枝纳米棒(B-NR)阵列。 利用低温化学浴沉积法(CBD)在TiO₂纳米棒阵列(NRA)和TiO₂分枝纳米棒阵列(B-NRA)基底上沉积Sb₂S₃纳米粒子(NPs)。 接着分别旋涂聚-3已基噻吩(P3HT)和2,2'7,7'-四-(二甲氧基二苯胺)螺芴(Spiro-OMeTAD)组装成TiO₂(NRA)/Sb₂S₃/P3HT/Spiro-OMeTAD和TiO₂(B-NRA)/Sb₂S₃/P3HT/ Spiro-OMeTAD为光活性层的杂化太阳电池。 结果表明,由TiO₂(NRA)/Sb₂S₃/P3HT/Spiro-OMeTAD复合膜结构组装的杂化太阳电池的光电转换效率(PCE)是2.92%,而由TiO₂(B-NRA)/Sb₂S₃/P3HT/Spiro-OMeTAD复合膜结构组装的杂化太阳电池的PCE提高到了4.67%。     

盘状多酸P_5W_(30)/阳离子聚电解质/氧化石墨烯杂化多层膜的电致变色性能

为了提高薄膜[PEI/P_5W_(30)]_(30)的电致变色性能,将具有大的二维尺寸和良好导电性的氧化石墨烯引入该薄膜中。通过层层自组装(LBL)技术构筑了基于盘状多酸K12.5Nal.5[Na P_5W_(30)O_(110)]·15H_2O(P_5W_(30))、氧化石墨烯(GO)的复合薄膜[PEI/P_5W_(30)/PEI/GO]_(30)(PEI:聚乙烯亚胺),并利用UV-Vis光谱对薄膜的组成及增长进行监测;通过原子力显微镜对薄膜的表面形貌进行考察,利用循环伏安法对薄膜电化学氧化还原性质进行研究;薄膜在外加氧化还原电位下呈现出无色/蓝色的可逆变化,电致变色响应时间在10 s以内;此外,薄膜在阶跃电位0.75 V/-0.75 V下循环150次,电致变色性能没有明显减弱,体现了薄膜良好的电致变色可逆性。氧化石墨烯的引入使薄膜[PEI/P_5W_(30)/PEI/GO]_(30)呈现出响应速度快、抗电疲劳强的电致变色性能,将在电致变色器件领域有广阔的应用前景。     

Electrochromic properties of a metallo-supramolecular polymer derived from tetra(2-pyridyl-1,4-pyrazine) ligands integrated in thin multilayer films

The electrochromic behavior of iron complexes derived from tetra-2-pyridyl-1,4-pyrazine (TPPZ) and a hexacyanoferrate species in polyelectrolytic multilayer adsorbed films is described for the first time. This complex macromolecule was deposited onto indium-tin oxide (ITO) substrates via self-assembly, and the morphology of the modified electrodes was studied using atomic force microscopy (AFM), which indicated that the hybrid film containing the polyelectrolyte multilayer and the iron complex was highly homogeneous and was approximately 50 nm thick. The modified electrodes exhibited excellent electrochromic behavior with both intense and persistent coloration as well as a chromatic contrast of approximately 70%. In addition, this system achieved high electrochromic efficiency (over 70 cm(2) C(-1) at 630 nm) and a response time that could be measured in milliseconds. The electrode was cycled more than 10(3) times, indicating excellent stability.     

Layer-by-layer assembled microgel films with high loading capacity: reversible loading and release of dyes and nanoparticles

Multilayer films containing microgels of chemically cross-linked poly(allylamine hydrochloride) (PAH) and dextran (named PAH-D) were fabricated by layer-by-layer deposition of PAH-D and poly(styrene sulfonate) (PSS). The successful fabrication of PAH-D/PSS multilayer films was verified by quartz crystal microbalance measurements and cross-sectional scanning electron microscopy. The as-prepared PAH-D/PSS multilayer films can reversibly load and release negatively charged dyes such as methyl orange (MO) and fluorescein sodium and mercaptoacetic acid-stabilized CdTe nanoparticles. The loading capacity of the film for MO can be as large as approximately 3.0 microg/cm2 per bilayer, which corresponds to a MO density of 0.75 g/cm3 in the film. The high loading capacity of the PAH-D/PSS films originates from the cross-linked film structure with sufficient binding groups of protonated amine groups, as well as their high swelling capability by solvent. The loaded material can be released slowly when immersing the films in 0.9% normal saline. Meanwhile, the PAH-D/PSS multilayer films could deposit directly on either hydrophilic or hydrophobic substrates such as quartz, polytetrafluoroethylene, polystyrene, poly(ethylene terephthalate), and polypropylene. The microgel films of PAH-D/PSS are expected to be widely useful as matrixes for loading functional guest materials and even for controlled release.     

Dye-sensitized solar cells made from BaTiO3-coated TiO2 nanoporous electrodes

We reported on the preparation of a thin BaTiO₃-coated layer (2.27 nm) on the surface of TiO₂ and its further application in the dye-sensitized solar cells (DSCs). The as-prepared BaTiO₃–TiO₂ films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The performances of the DSCs with and without BaTiO₃ coating were analyzed by cyclic voltammograms (CVs), electrochemical impedance spectroscopy (EIS), and current–voltage measurements. It was found that the BaTiO₃–TiO₂ films with about 12 μm thickness increased the dye adsorption, resulting in increased J_sc. In the meantime, the BaTiO₃ modification on the TiO₂ surface is beneficial to the formation of an energy barrier against the electron transfer from TiO₂ to I₃⁻, providing the increase of V_oc due to the increased electron density in the TiO₂ that is caused by the increased electron lifetime.     

用MO-CVD技术制备金属氧化物薄膜及其光电化学行为

有机金属化学汽相沉积(MO-CVD)技术是一种新型薄膜材料制备技术,它优于目前通常采用的一般CVD和物理方法^[1]。主要优点:采用金属有机化合物为物质源,选择的范围比较大,其中含有易断裂的M-C键,易发生气相热分解氧化反应,成膜温度比较低,反应副产物仅有易挥发的碳氢化合物,使成膜环境无污染,易获得优质膜。因该技术是化学成膜,排除了物理方法中固有的不易控制化学计量的问题,易获得优质膜层。     

引入应力的锐钛矿TiO_2(001)薄膜的外延生长

锐钛矿TiO_2(001)(anataseTiO_2(001),简记为ATO)表面因其优异的催化活性受到了广泛的关注。理论计算结果表明,ATO表面应力导致的晶格畸变可能会增强该表面的催化活性。因此有必要研究应力对ATO表面结构的影响。本文利用BaTiO_3(001)(简记为BTO)与ATO之间存在较大的晶格失配度,将ATO薄膜外延生长在BTO衬底上从而引入应力,研究了存在应力情况下的ATO薄膜的结构特征。实验中,利用脉冲激光沉积方法在Nb掺杂的SrTi O_3(001)(简记为STO)单晶衬底上制备了ATO/BTO/STO外延薄膜。X射线衍射(XRD)和扫描透射电子显微术(STEM)结果表明,作为应力引入层的BTO薄膜厚度约为4–6nm时,能够部分地将应力引入到ATO薄膜中。X射线光电子能谱(XPS)结果显示,ATO薄膜合适的厚度应大于15 nm,从而降低从衬底反向扩散至表面的Sr和Ba原子的浓度;Ti 2p的高分辨XPS谱仅呈现出Ti~(4+)峰,表明ATO表面Ti原子为完全氧化的价态。ATO外延薄膜表面的扫描隧道显微术(STM)图像仍然呈现为(1×4)重构的结构,但在(1×4)重构的脊上存在明暗交替并具有一定周期性的特征。根据完全氧化的"增氧原子模型"(ad-oxygen model,AOM),脊上观察到的明暗交替特征可归因于表面应力导致的"TiO_2"空位缺陷结构。     

Fabrication of free-standing multilayer films by using pH-responsive microgels as sacrificial layers

A facile way to prepare free-standing polyelectrolyte multilayer films of poly(sodium 4-styrenesulfonate)(PSS)/poly(diallyldimethylammonium)(PDDA) was developed by applying a new pH-dependent sacrificial system based on cross-linked poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) microgels. The tertiary amine groups of PDMAEMA microgels can be protonated in acidic environment, and the protonated microgels were deposited by layer-by-layer (LbL) technique with PSS. PSS/PDDA multilayer films were constructed on the top of the PSS/microgels sacrificial layers. The LbL assembly process was investigated by UV–vis spectroscopy. Further study shows that the free-standing PSS/PDDA multilayer films can be obtained within 3 min by treating the as-prepared films in alkali aqueous solution with a pH of 12.0. The pH-triggered exfoliation of PSS/PDDA multilayer films provides a simple and facile way to prepare LbL assembled free-standing multilayer films.     

钒钨酸盐/刚果红电致变色复合膜及器件研究

应用Layer-by-Layer自组装技术, 采用聚乙烯亚胺(PEI)阳离子将无机电致变色材料[P₂W₁₅V₃O₆₂]^8?(P₂W₁₅V₃)阴离子与刚果红(CR)阴离子通过静电引力复合, 构筑了复合膜[PEI/P₂W₁₅V₃/PEI/CR]₂₀及对比膜 [PEI/P₂W₁₅V₃]₂₀. 利用扫描电子显微镜、 紫外-可见吸收光谱和电化学工作站研究了复合膜的形貌与电致变色性能. 对比研究表明, 复合膜可实现浅红色-蓝紫色-浅红色的可逆颜色调变, 且保持了[P₂W₁₅V₃O₆₂]^8?阴离子的电致变色性能, 光反差22.55%, 着色效率122.67 cm²/C.复合膜循环测试400圈后透过率(500 nm)处损耗仅为6.94%, 稳定性良好; 由复合膜组装的电致变色器件也实现了由浅红色到蓝紫色的颜色变化. 本研究可为解决多酸电致变色材料颜色变化单一的问题提供参考.     

柔性不锈钢基底上一维TiO_2纳米线薄膜的制备及表征

采用直流磁控溅射的方法在柔性不锈钢基底(50μm)上沉积纯钛薄膜,后在NaOH碱溶液中经水热法制备了非钛基大长径比的一维TiO2纳米线薄膜,并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、透射电子显微镜(TEM)以及光电化学的方法对不锈钢基一维TiO2纳米线薄膜进行了表征.结果表明,纯钛薄膜的致密度、结晶性能以及与基底的结合强度均随衬底温度的升高而加强;在10mol·L-1NaOH浓度下,生长一维TiO2纳米线结构的适宜温度为130-150℃;TiO2纳米线长度达到几个微米,直径在10-30nm之间,并且相互交叉生长,构成一个三维网络结构.此外,在Na2SO4溶液中对TiO2纳米线薄膜进行了线性扫描和瞬态光电流测试,结果表明,一维TiO2纳米线薄膜电极较TiO2纳米颗粒电极表现出更优异的光电化学性能.这种磁控溅射与水热反应相结合的方法,为非钛异质基底上制备一维TiO2纳米线薄膜提供了新的思路.