Organized multilayers

A strong surface charge on the halloysite tubules has been exploited for designing nano-organized multilayers using the layer-by-layer (LbL) method of Lvov et al. [8,13,14]. The lumen of the halloysite has been used as an enzymatic nano-reactor by Shchukin et al. [15] The biocompatible nature of the halloysite was... 

An important feature of surfactant monolayers is their transferability from the air-water interface to clean, smooth, solid supports such as glass or metal surfaces. Blodgett and Langmuir (67) developed this technique and employed it for building up multilayers whose thickness was that of a known number of molecular chain lengths. Recently, there has been considerable interest in the application of this technique to prepare organized multilayers for the study of optical, electrical, and catalytic properties of very thin films of known composition (47,53-55). 

Surfactants provide several types of well-organized self-assembhes, which can be used to control the physical parameters of synthesized nanoparticles, such as size, geometry and stability within liquid media. Estabhshed surfactant assembles that are commonly employed for nanoparticie fabrication are aqueous micelles, reversed micelles, microemulsions, vesicles [15,16], polymerized vesicles, monolayers, deposited organized multilayers (Langmuir-Blodgett (LB) films) [17,18] and bilayer Upid membranes [19](Fig. 2). 

Organized multilayers of ferrocene alkyl thiol have been self-assembled on Au(lll) under conditions of controlled thiol concentration. Several methods, such as CV, ellipsometry, STM, AFM, and in situ FTIR spectroscopy have been applied in these studies in order to find out the differences between mono- and multilayers of the same compound [152]. Similar compounds, namely, short-chain alkyl thiols (n = 3-10) with ferrocene terminal group were allowed to form organized monolayers at Au(lll) surfaces [153]. 

Figure 10. (A) The stepwise assembly and electrical contacting of a cross-linked organized multilayer array of glucose oxidase (GOx) on an An electrode. (B) Cyclic voltammograms of the GOx/ ferrocene-modified electrode in the presence of glucose (20 mM) in (a) one-, (b) four- and (c) eight-layer configurations. Inset amperometric responses of the four-layer GOx array at 0.4 V vs. SCE as a function of glucose concentration. Recorded in 0.1 M phosphate buffer, pH 7.3, under argon.

R.H. Tredgold, Ordered Organic Multilayers, J. Mater. Chem., 5 (1995) 1095. (Short review basics of LB, self-assembly and other techniques interesting developments and aspects of particular scientific Importance.)... 

Next, in the 1980s, the organic multilayer structures, which are another key technology of present high-performance OLEDs, appeared. In 1986, Hayashi et al. observed a remarkable reduction of the driving voltage by inserting a polythiophene-electropolymerized thin film between an indium-tin-oxide (ITO) anode and a perylene-deposited film.30 The insertion of the polythiophene thin... 

In addition, we should mention the exciplex formation between adjoining molecules, which is frequent and poses a serious problem for obtaining pure EL colors and high efficiency in organic multilayer solid devices 46... 

Another significant merit of organic multilayer structures is keeping the energy of molecular excitons from dissipating into the metal electrodes — in other words, the retardation effect between an excited molecule and a metal mirror.53 It is well known that if excited molecules located near a metal electrode are less than 20 nm, the nonradiative energy transfer to the metal electrode dominantly occurs. Thus, the 50-70-nm-thick HTL and ETL effectively protect molecular excitons from the dissipation process. 

Booking T., James M., Coster H. G. L., Chilcott T. C. and Barrow K. D. (2004), Structural characterization of organic multilayers on silicon(lll) formed by immobilization of molecular films on functionalized Si-C linked monolayers , Langmuir 20, 9227-9235. 

Lim J T, Lee N H, Ahn Y J, Kang G W and Lee C H, White-light-emitting devices based on organic multilayer structure Current Applied Physics, 2,4, (August 2002), 295-298... 

These observations clearly reveal that (room temperature) STM is not the method of choice for the investigation of organic multilayers, especially in the presence of islanding, and also explain the discrepancy between our data and the STM-results reported for the growth of thin films of pentacene and pery-lene on clean metal surfaces [56, 58]. 

A Langmuir film balance can also be used to build up highly organized multilayers of surfactant films on solid substrates. This is accomplished by successively dipping a substrate... 

Let us now consider organic multilayers in which molecules have no center of inversion and where, as a result, they possess static dipole moments in stationary states. If, in this case, the dipole-dipole interaction dominates, the relations for a G-CM shift including this shift at interfaces will change. Consider the case of an interface between crystals formed by molecules A and B. In this case the quantity DABt can be written in the following way ... 

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