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Mesoporous films

SEM image of the surface of a mesoporous film prepared from colloidal Ti02. [Pg.727]

Zhang, B.J., Davis, S.A. and Mann, S. (2002) Starch gel templating of spongelike macroporous silicalite monoliths and mesoporous films. Chemistry of Materials, 14, 1369-1375. [Pg.108]

Invented less than a decade ago,1 EISA has rapidly developed into a universal technique for fabrication of organized porous and patterned nanocomposite materials, ranging from metal oxides and chalcogenides to carbons, polymers, and metals.2,3 In addition to generating ordered mesoporous films, this technique may also be used to incorporate functional molecules and... [Pg.283]

The number of publications concerning utilization of the EISA process for fabrication of different structured materials is counted in the hundreds, which is far beyond the possibilities of this chapter to review in depth. Rather, we intend to provide a brief introduction into EISA and its application to the fabrication of functional thin films for electronic applications (e.g., electro-chromic layers and solar cells), with a special focus on fabrication of crystalline mesoporous films of metal oxides. Attention will also be given to techniques used to evaluate the pore structure of the thin films. For the other aspects of the EISA process, for example its mechanism,4 strategies for preparation of crystalline porous metal oxides,5 mesoporous nanohybrid materials,6 periodic organic silica materials,7,8 or postgrafting functionalization of mesoporous framework,9 we kindly recommend the reader to refer to the referenced comprehensive reviews. [Pg.284]

This category includes a large variety of silica, zirconia, and alumina mesoporous films. Although the inorganic scaffold of such layers does not transport electric current, the pore architecture, which can be also used as a host matrix for incorporation of functional molecules, can alter electron transport to and from the conducting surface, thus influencing electronic properties of the complete system. [Pg.299]

The investigation of possible utilization of EISA-manufactured layers in electronic applications has started relatively recently, but the already performed studies demonstrate a very high potential of mesoporous films for technologies using interfacial and bulk charge transport. The advantages of the EISA-prepared layers become especially evident when the interfacial charge transfer from the species attached to the interface plays the key role in system performance. [Pg.302]

These experiments indicated that an increase of solar conversion efficiency on the order of 50% can be achieved for cells containing Ti02 mesoporous films with a thickness >1 pm.5... [Pg.305]

Figure 9.7. Illustration of the usage of mesoporous films of transparent conducting oxides for novel types of solar cells. The dark gray areas correspond to ITO, the brighter ones to an oxide deposited onto the TCO matrix. The sphere symbolizes a dye. For instance, such films can be used as porous electrodes to include dyes and to deposit semiconductors such as ZnO. [Pg.306]

Grosso, D. Boissiere, C. Smarsly, B. Brezesinski, T. Pinna, N. Albouy, P. A. Amenitsch, H. Antonietti, M. Sanchez, C. 2004. Periodically ordered nanoscale islands and mesoporous films composed of nanocrystalline multimetallic oxides. [Pg.310]

The stress of oxidized PS layers is always compressive. For porous oxides, values below 108 N nT2 are reported [Ba5], which is nearly one order of magnitude smaller than values of intrinsic stress generated by low-temperature thermal oxidation of bulk silicon. The compressive stress in OPS has successfully been used to lift up released mesoporous films and thereby fabricate 3D microstructures [La9],... [Pg.159]

To detail DSSC technologies, Fig. 18.1 illustrates the modus operandi of DSSCs. Initially, light is absorbed by a dye, which is anchored to the surface of either n- or p-type semiconductor mesoporous electrodes. Importantly, the possibility of integrating both types of electrodes into single DSSCs has evoked the potential of developing tandem DSSCs, which feature better overall device performances compared to just n-or p-type based DSSCs [19-26]. Briefly, n-type DSSCs, such as TiOz or ZnO mesoporous films, are deposited on top of indium-tin oxide (ITO) or fluorine-doped tin oxide (FTO) substrates and constitute the photoanodes. Here, charge separation takes place at the dye/electrode interface by means of electron injection from the photoexcited dye into the conduction band (cb) of the semiconductor [27,28]. A different mechanism governs p-type DSSCs, which are mainly based on NiO electrodes on ITO and/or FTO substrates... [Pg.476]

As discussed in the previous section, one of the major DSSC bottlenecks is the charge transport across the electrode network. Recently, different groups have demonstrated that implementation of nanocarbons in the form of (i) interlayers on the bottom and/or on top of the mesoporous film, and (ii) dopants inside the electrode network, is a very powerful strategy to overcome this issue. In this section, the most relevant aspects are outlined. [Pg.479]

The application of anion receptors in sensing has been mentioned earlier. Dioxatetraazamacrocycles 381 were synthesized for the application in chiral anion recognition [43]. Mesoporous films by 382 were developed to be used as sensors for volatile organic compounds [44]. Receptors for anions were also studied to mimic their transport through membranes [45]. [Pg.264]

In summary, the electronic recapture involving I3 is kinetically so slow on both 2 and Sn02 surfaces that, under short-circuit conditions, most of electrons survive the transit through the mesoporous film and the Sn02 surface and appear in the... [Pg.537]

Season et al.52) reported that the IMPS response of dye-sensitized TiOz mesoporous film is described by a diffusion model and the diffusion coefficient in the film depends on light intensity, where the electron transfer process is explained by thermal excitation from trap sites of the particles. [Pg.175]

Particularly in 2D systems, control over the self-assembly of colloidal templates has offered a versatile way to produce patterned surfaces or arrays with a precision of few nanometres. Diblock copolymer micellar nanolithography (dBCML) is a versatile method that uses homopolymers or block copolymers for the production of complex surface structures with nanosized features [69], In contrast to other approaches like electron-beam lithography (EBL) and photolithography, dBCML does not require extensive equipment. In fact, it is commonly used in the fabrication of data storage devices and photonic crystals, in catalyses [70], and for the design of mesoporous films and nanoparticle arrays [71]. [Pg.88]

Further functionalization of mesoporous films with the pH-sensitive dye fluorescein was accomplished by Wirnsberger et al.204 The organosilane used for the actual co-condensation reaction was first prepared by reaction of fluorescein isothiocyanate (FITC) with APTES. The possible use of the dye-modified films as pH sensors was investigated by measurement of the fluorescence after excitation with an Argon laser (488 nm) a dramatic change in fluorescence intensity was observed around pH 8 with a response time of a few seconds. [Pg.71]

Azobenzene has also been added to the internal surface of mesoporous films and powders through postsynthesis grafting.58,60-62 The effect of oligomer size on azobenzene isomerization kinetics was studied for branched oligomer-modified azobenzene derivatives in solution and covalently grafted to nanoporous silica 61 the size of the dendrimer had little effect on the thermal cis to trans isomerization rate in solution... [Pg.539]

The classic sensitizer dye employed in DSC is a Ru(II) bipyridyl dye, cis-bis(isothiocyanato)-bis(2,2/-bipyridyl-4,4/-dicarboxylato)-Ru(II), often referred to as N3 , or in its partially deprotonated form (a di-tetrabutyl-ammonium salt) as N719. The structure of these dyes are shown in 2 and 26. The incorporation of carboxylate groups allows immobilization of sensitizer to the film surface via the formation of bidendate coordination and ester linkages, whilst the (- NCS) groups enhance the visible light absorption. Adsorption of the dye to the mesoporous film is achieved by simple immersion of the film in a solution of dye, which results in the adsorption of a dye monolayer to the film surface. The counter electrode is fabricated from FTO-coated glass, with the addition of a Pt catalyst to catalyze the reduc-... [Pg.118]


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