Highly luminescent network films from electrochemical deposition of peripheral carbazole functionalized fluorene oligomer and their applications for light-emitting diodes

Highly luminescent network films on flat indium tin oxide (ITO) substrates are prepared by electropolymerization using an electroactive and fluorescent compound as precursor; the LEDs prepared using these films as a light emitting layer achieve the maximum luminance and external quantum efficiency of 4224 cd/m(2) and 0.72%, respectively, which demonstrates that electrochemical synthesis can be a new route to construct the highly luminescent films.     

循环伏安法制聚(1,5-萘二胺)膜及其对紫外可见光吸收的研究

利用循环伏安法合成了1,5-萘二胺(1,5DAN)聚合物膜.从反应的介质、膜的厚度以及掺杂酸的种类等方面,讨论了制备电活性聚1,5-萘二胺(P1,5DAN)膜的影响,结果发现,在酸性水溶液中,初始的电活性比较高,但是,随着循环的继续,聚合物膜的电量损耗比较大,而在乙腈溶液中电量损耗较小;同时还发现,P1,5DAN电活性膜的厚度并不随总电量的增加而增厚;活性聚合物膜是受扩散控制,扩散系数(D)与酸根离子有关.最后,结合电化学,讨论了不同掺杂状态下的紫外可见吸收光谱(UV-Vis),并用FT-IR对所合成的聚合物作了结构表征.     

Electrochemistry of cytochrome c incorporated in Langmuir-Blodgett films of Nafion and Eastman AQ 55

Ultrathin films of Nafion and Eastman-AQ 55 loaded with cytochrome c (cyt c) were obtained and transferred on indium tin oxide (ITO) electrodes via the Langmuir-Blodgett (LB) technique. The pressure-area isotherms for mixed ionomer-protein films indicate that the miscibility of cyt c in the interfacial layer is better for Nafion than for AQ 55. Interestingly, these composite films maintain the electroactivity of cyt c without requiring the addition of promoters or mediators. Both for AQ 55-cyt c and Nafion-cyt c films, the half-wave potential for the reversible reduction of ferricytochrome c corresponds to the value expected for the weakly adsorbed protein. The modified electrodes show electrocatalytic reaction with ascorbate anion. Comparison with previous literature reports indicate that for Nafion the LB coating procedure is unique in keeping the electroactivity of cyt c.     

A Dual Functional Electroactive and Fluorescent Probe for Coupled Measurements of Vesicular Exocytosis with High Spatial and Temporal Resolution

In this work, Fluorescent False Neurotransmitter 102 (FFN102), a synthesized analogue of biogenic neurotransmitters, was demonstrated to show both pH‐dependent fluorescence and electroactivity. To study secretory behaviors at the single‐vesicle level, FFN102 was employed as a new fluorescent/electroactive dual probe in a coupled technique (amperometry and total internal reflection fluorescence microscopy (TIRFM)). We used N13 cells, a stable clone of BON cells, to specifically accumulate FFN102 into their secretory vesicles, and then optical and electrochemical measurements of vesicular exocytosis were experimentally achieved by using indium tin oxide (ITO) transparent electrodes. Upon stimulation, FFN102 started to diffuse out from the acidic intravesicular microenvironment to the neutral extracellular space, leading to fluorescent emissions and to the electrochemical oxidation signals that were simultaneously collected from the ITO electrode surface. The correlation of fluorescence and amperometric signals resulting from the FFN102 probe allows real‐time monitoring of single exocytotic events with both high spatial and temporal resolution. This work opens new possibilities in the investigation of exocytotic mechanisms.     

Charge transport and optical properties of MOCVD-derived highly transparent and conductive Mg- and Sn-doped In2O3 thin films

Mg- and Sn-doped In2O3 (MgIn(x)Sn(y)O(z), 6.0 < x < 16.0; 3.0 < y < 8.0) thin films were grown by low-pressure metal-organic chemical vapor deposition using the volatile metal-organic precursors tris(2,2,6,6-tetramethyl-3,5-heptanedionato)indium(III) [In(dpm)3], bis(2,4-pentanedionato)tin(II) [Sn(acac)2], and bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(N,N,N',N'-tetramethylethylenediamine)magnesium(II) [Mg(dpm)2(TMEDA)]. Films in this compositional range retain the cubic In2O3 bixbyite crystal structure. The highest conductivity is found to be approximately 1000 S/cm for an as-grown film with a nominal composition MgIn14.3Sn6.93O(z). Annealing of such films in a vacuum raises the conductivity to approximately 2000 S/cm. The optical transmission window of the present films is significantly wider than that of typical indium tin oxide (ITO) films from 300 to 3300 nm, and the transmittance is also greater than or comparable to that of commercial ITO films.     

Synthesis of indium tin oxide films from ethyl acetoacetonato complexes at low temperatures

Journal of Sol-Gel Science and Technology - A novel recycling system for indium in indium tin oxide (ITO), which comprises the dissolution of indium oxide (In2O3), chlorination, chelation, and...     

Advanced surface modification of indium tin oxide for improved charge injection in organic devices

A new method is described for surface modification of ITO with an electroactive organic monolayer. This procedure was done to enhance hole injection in an electronic device and involves sequential formation of a monolayer of a pi-conjugated organic semiconductor on the indium tin oxide (ITO) surface followed by doping with a strong electron acceptor. The semiconductor monolayer is covalently bound to the ITO, which ensures strong adhesion and interface stability; reduction of the hole injection barrier in these devices is accomplished by formation of a charge-transfer complex by doping within the monolayer. This gives rise to very high current densities in simple single layer devices and double layer light emitting devices compared to those with untreated ITO anodes.     

Novel guests for porous columnar thin films: the switchable perchlorinated trityl radical derivatives

TiO(2) and SiO(2) porous thin films consisting of tilted nanocolumns prepared by glancing angle evaporation (GLAD) have been infiltrated with guest derivatives belonging to the family of perchlorinated trityl radicals, novel guest molecules presenting an open-shell electronic configuration associated with paramagnetism, fluorescence, and electroactivity. The main driving forces for infiltration from aqueous solutions of the carboxylate-substituted radical derivatives are the electrostatic interactions between their negative charge and the net positive charges induced on the film pores. Positive charges on the internal surface of the films were induced by either adjusting the radical solution pH at values lower than the point of zero charge (PZC) of the oxide or passivating the nanocolumns oxide surface with a positively charged aminosilane. The infiltrated composite thin films are robust and easy to handle thanks to the physical protection exerted by the film columns. They also keep the multifunctionality of the used guests, as confirmed by electron paramagnetic resonance (EPR), UV-vis spectroscopy, and fluorescence spectroscopy. To prove the electroactivity of the infiltrated porous films, a porous TiO(2) host layer was supported onto conductive indium tin oxide (ITO). By application of an appropriate redox potential, the guest radical molecules have been reversibly switched from their open-shell electronic configuration to their diamagnetic state and hence changed their optical properties. On the basis of these results, it is herein proposed that the appropriate surface functionalization of the pore internal surface of GLAD thin films can be used to prepare novel radical-oxide composite thin films usable for the development of robust switchable electrically driven photonic and magnetic devices.     

A novel precursor system and its application to produce tin doped indium oxide

A new type of precursor has been developed by molecular design and synthesised to produce tin doped indium oxide (ITO). The precursor consists of a newly developed bimetallic indium tin alkoxide, Me(2)In(O(t)Bu)(3)Sn (Me = CH(3), O(t)Bu = OC(CH(3))(3)), which is in equilibrium with an excess of Me(2)In(O(t)Bu). This quasi single-source precursor is applied in a sol-gel process to produce powders and coatings of ITO using a one-step heat treatment process under an inert atmosphere. The main advantage of this system is the simple heat treatment that leads to the disproportionation of the bivalent Sn(II) precursor into Sn(IV) and metallic tin, resulting in an overall reduced state of the metal in the final tin doped indium oxide (ITO) material, hence avoiding the usually necessary reduction step. Solid state (119)Sn-NMR measurements of powder samples confirm the appearance of Sn(II) in an amorphous gel state and of metallic tin after annealing under nitrogen. The corresponding preparation of ITO coatings by spin coating on glass leads to transparent conductive layers with a high transmittance of visible light and a low electrical resistivity without the necessity of a reduction step.     

Role of Layer-by-Layer Deposition on Electrical and Optical Properties of PEDOT: PSS/Polyaniline Thin Films for Solar Cells

In this article, electrical and optical properties of PEDOT:PSS/Polyaniline: (PANI)bilayer thin films deposited on indium tin oxide (ITO) are reported. Spin coater has been used for fabrication of thin films of 40–50 nm thickness at 5000 rpm. The deposited thin films have been characterized by using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), UV-vis spectroscopy and Keithley electrometer. Layer-by-layer (LBL) technique has been shown to produce electroactive polymer films with low roughness, excellent uniformity, and high electrical conductivity for heterojunction solar cells. The electrical response of fabricated films showing ohmic behavior for PEDOT: PSS/PANI thin films.     

Microstructure analysis of sol‐gel‐derived nanocrystalline ITO thin films

The technique for ITO (Tin‐doped indium oxide) thin films by sol‐gel process is presented in this paper. After annealing at 500° for 15 min, ITO gel films get transformed into nanocrystallined indium tin oxide films. We studied the microstructure of ITO thin film which is closely related to optical and electrical properties. The microstructure of ITO thin film can be observed through high‐resolution transmission electronic spectroscopy (HRTEM) and the Fast Fourier Transform (FFT) technique. The film is nanocrystallite with grain sizes about 20 nm. Also, the surface chemical components were studied by XPS spectra. The transmission and the resistivity of ITO films is 97.0% and 3.5 × 10^?3 Ω?cm, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Calculation of the electronic and optical properties of indium tin oxide by density functional theory

Density functional theory (DFT) was used to calculate the bulk electronic and optical properties of indium tin oxide (ITO). The ITO model was constructed replacing indium atoms with tin atoms in the cubic unit cell of indium oxide. To allow more possibilities for tin atom substitution than afforded by the forty-atom primitive cell of indium oxide all eighty atoms of the unit cell were included in the stoichiometry (In_32−xSn_xO₄₈) using periodic boundary conditions. A number of properties of ITO were calculated including the optical band gap, charge carrier density and plasma frequency. The dependence of the electronic and optical properties of ITO on a variety of parameters such as the tin content, cubic lattice parameter and the distance between adjacent tin atoms was investigated. The electronic and optical properties agreed well with experimental data and allowed insight into the origin of the electronic and optical properties of ITO.     

Molecular organization and electrochemical reduction of a Ni(II)Porphyrin complex in LB films

In this work, mixed films of a tetra-cationic porphyrin, Ni(II)TMPyP, and an anionic phospholipid, DMPA, in molar ratio of 1:4, were formed at the air–water interface and transferred onto glass and optically transparent indium tin oxide (ITO) electrodes. Transmission spectroscopy (on glass and ITO) and cyclic voltammetry (on ITO) were used to infer the molecular organization and the electrochemical reduction of these LB films. Likewise, we compare the electrochemical reduction of the Ni(II)TMPyP in water solution with that in LB films. The porphyrin molecules in water solution show three two-electron reduction waves, which are related to the two-electron reduction of the central ring of the porphyrin and to the one-electron reductions of the four methyl–pyridyl groups of the molecule, respectively, while only two reversible one-electron reduction waves are observed in LB films corresponding to the reduction of the central ring of the porphyrin and to the Ni(II) to Ni(I) reduction, respectively.     

Phenylphosphonic acid functionalization of indium tin oxide: surface chemistry and work functions

The work function of indium tin oxide (ITO) substrates was modified with phosphonic acid molecular films. The ITO surfaces were treated prior to functionalization with a base cleaning procedure. The film growth and coverage were quantified by contact angle goniometry and XPS. Film orientation was determined by reflection/absorption infrared spectroscopy using ITO-on-Cr substrates. The absolute work functions of nitrophenyl- and cyanophenyl-phosphonic acid films in ITO were determined by Kelvin probe measurement to be 5.60 and 5.77 eV, respectively.     

Microfabrication and imaging XPS analysis of ITO thin films

In this paper the microfabrication of ITO (tin‐doped indium oxide) films by the sol–gel process combined with chemical modification is presented. The microfabricated ITO thin film could be obtained through a one‐step process that combines film patterning with film leaching. The morphology and chemical components of the patterned ITO thin films were assessed by microscopy and XPS, respectively. Imaging XPS analysis is an effective way to evaluate the quality of the fine patterning. Copyright © 2007 John Wiley & Sons, Ltd.     

Fabrication and characterization of copper nanoparticle thin-films and the electrocatalytic behavior

Copper nanoparticles, stabilized by cysteine, have been formed thin-films on indium tin oxide (ITO) electrodes with (3-mercaptopropyl) trimethoxysilane (MPTMS). Scanning electron micrograph (SEM) demonstrates that the films are uniform and the copper nanoparticles are homogeneously distributed on the ITO electrode surface. Electrochemical experiments reveal that the obtained copper nanoparticles modified electrodes show improved electron-transfer characteristics and exhibit high electrocatalytic activity to the reduction of nitrite and nitric oxide, which can be utilized as an efficient electrochemical sensor.     

Renewable and optically transparent electroactive indium tin oxide surfaces for chemoselective ligand immobilization and biospecific cell adhesion

In this report, we show the successful transfer of a sophisticated electroactive immobilization and release strategy to an indium tin oxide (ITO) surface to generate (1) optically transparent, robust, and renewable surfaces, (2) inert surfaces that resist nonspecific protein adsorption and cell attachment, and (3) tailored biospecific surfaces for live-cell high-resolution fluorescence microscopy of cell culture. By comparing the surface chemistry properties on both ITO and gold surfaces, we demonstrate the ITO surfaces are superior to gold as a renewable surface, in robustness (durability), and as an optically transparent material for live-cell fluorescence microscopy studies of cell behavior. These advantages will make ITO surfaces a desired platform for numerous biosensor and microarray applications and as model substrates for various cell biological studies.     

HAXPES of protected ITO surfaces at the buried P3HT/ITO interface

The characterization of buried interfaces is difficult and often has to be performed by a post‐processing method where the interface is exposed. Hard energy X‐ray photoelectron spectroscopy offers the ability to tune the X‐ray energy and thereby change the information depth. In this work, an inorganic/organic interface was evaluated, namely the poly(3‐hexylthiophene) (P3HT) interface with indium tin oxide (ITO), with relevance to organic photovoltaic devices. P3HT/ITO buried interfaces were examined using three X‐ray energies where the ITO surface was prepared under different pretreatment conditions. The P3HT film protected the ITO surface from adventitious adsorbents and allowed for sensitivity to the buried ITO surface. Robust peak fitting parameters were obtained to model the O 1 s and In 3d lineshapes. The deconvolution of these lineshapes allowed for the clear identification of a surface layer on the ITO which is oxidized to a greater extent than the underlying bulk ITO. The surface oxide layer, composed of indium oxide and indium hydroxide, is deficient of oxygen vacancies and would therefore be expected to act as an insulating barrier on the ITO surface. Peak fitting conditions allowed for an estimation of the relative thicknesses of this insulating layer. Copyright © 2012 John Wiley & Sons, Ltd.     

Amperometric sensing of hydrogen peroxide via an ITO electrode modified with gold nanoparticles electrodeposited on a CoMn-layered double hydroxide

Microchimica Acta - An electrochemical sensor for hydrogen peroxide (H2O2) has been fabricated by electrodepositing gold nanoparticles (AuNPs) on an indium tin oxide (ITO) electrode modified with...     

Studies on electro‐optical properties of polymer matrix/LC/ITO nanoparticles composites

In this paper, polymer‐dispersed liquid crystal (PDLC) films consisting of liquid crystal (LC)/monomers/indium tin oxide (ITO) nanoparticles with good near‐infrared absorption property had been fabricated, and the influence of the ITO nanoparticles modified with 3‐methacryloxypropyltrimethoxysilane (KH570) on the PDLC films was systematically studied. First, different liquid crystal content was studied to obtain PDLC films with good electro‐optical properties. And then, various weight ratio of ITO nanoparticles was added to samples. While the content of ITO nanoparticles was increased, the saturation voltage increased and the CR decreased. Though the electro‐optical properties of PDLC samples reduced with the addition ITO nanoparticles, the near‐infrared absorption property of films was enhanced.