Narrow Results

Tetrakis-4-(2,4-di-tert-amylphenoxy)phthalocyaninato-polysiloxane was synthesized. Its molecular structure was confirmed by elemental analysis, IR and UV-vis spectra. The gas-sensitive properties of its Langmuir–Blodgett films exposed to NH₃, I₂ and NO₂ in air were measured. The results showed that the detection sensitivity on exposure to NH₃ in air can reach 0.1 ppm, while it can reach 100 ppm on exposure to NO₂ and I₂ in air.

Tetrapyridotetraazaporphyrinatozinc (TPyTAPZn) can be looked at as a substituted phthalocyanine. Thin films of TPyTAPZn were prepared on quartz glass by physical vapour deposition under high-vacuum conditions. During the deposition, island growth was observed by a characteristic change in the electrical conduction, indicating an increasing number of conduction pathways along the film. Deposition conditions could be optimized to yield an ordered rather than amorphous growth as detected by a characteristic absorption band in the visible range, strongly red-shifted from the absorption of the monomeric molecule in solution. A negative Seebeck coefficient confirmed n-type conduction for TPyTAPZn. In temperature-dependent measurements of the electrical conductivity and thermopower across the samples an activation energy of 0.31 eV was established for the conductivity and of 0.04 eV for charge carrier generation. From this difference it is concluded that a thermally activated charge carrier transport mechanism (hopping) rather than delocalized conduction (band model) is dominant in TPyTAPZn. Photoconduction turned out to be rather small in these samples, although light was absorbed quite efficiently. The time dependence of photoconduction indicated a significant trap density. Interaction with ammonia or triethylamine in the gas phase led to an increase in the conductivity; oxygen or water led to a decrease. The time dependence of these interactions indicated that triethylamine and water were only reacting with the surface region, whereas NH₃ and O₂ were also diffusing into the bulk of the films.

Several recent studies of phthalocyanines and porphyrins as materials in emerging technologies are reviewed here. Emphasis is placed on the use of these materials as components in building materials where the symmetry, optical and electrical properties of the molecule are important. Aggregates or polymers of these molecules have been known for some time to possess interesting electrical conductivities, and more recently interesting optical properties. Their optical properties as isolated species in condensed phases have also recently become interesting, and their ability to form new hybrid materials, by mixing or by thin film deposition, with other molecules with different electron affinities and ionization potentials, now appears to be extremely attractive. Device technologies in which we can anticipate these molecules appearing in the near future include organic light-emitting diodes, organic field effect transisitors, organic photovoltaics, optical limiters and optically based chemical sensors.

ZnO is attracting intensive attention for its versatile applications in transparent electronics, UV emitter, piezoelectric devices, chemical sensor and spin electronics. As one of the direct wide band gap semiconductors, it has advantages over GaN due to its larger exciton binding energy, better lattice match on heteroepitaxial growth and availability of single crystal substrate. Large effort has been invested in the growth of nanostructured ZnO to explore its potentials for nanoscale device applications. ZnO nanobelts, nanowires, nanorings, and nanohelixes demonstrate the diversity of ZnO nanostructures family. This review presents recent research on ZnO nanostructures. Issues of synthesis methods, optical, electrical, gas sensing and magnetic properties are summarized. These progresses constitute the basis for developing future applications in nanoscale electronics, optoelectronics, chemical sensor and spintronics.

Multi-analyte chemical sensor aims to transform subtle variations in multiple analytes’ physical or chemical properties into distinct output signals. Chemically responsive nanostructure array (nanoarray) promises as a competitive sensor platform due to its robust physical properties, tunable chemical composition, and high surface area for analyte interaction. Specifically, the well-defined size, shape, and tunable surface structure and properties make it feasible to develop either new sensing modes on single device or integrated multi-modular sensors. In conjunction with the well-developed resistor-type sensors and sensor arrays, the complementary utilization of and intercorrelation with the electrochemical, optical, voltammetry modes in the multi-modular sensing strategies could provide multi-dimensional measurements to different analytes in a complex mixture form, where species information could be accurately and robustly separated from spatially collective responses. This review intends to provide a survey of the recent progress on multi-analyte sensing strategies and their unique structure design, as well as the related sensing mechanics in interaction of analytes and sensitizer and the behind mechanism for analytes’ differentiation.

The nature of electron transfer through intermolecular tunnel junctions has been studied. Intermolecular junctions feature non-hydrogen and hydrogen bonded interactions and are defined by the end groups of pairs of functionalized conjugated alkenes. We compared the distant dependent electron transfer from donor to acceptor group attached to the other sides of those functionalized conjugated alkenes. Study shows electron transfer coupling matrix element for these intermolecular junctions decays exponentially as a function of junction separation and quite substantial in energetically favourable hydrogen bonded intermolecular junctions.

Multi-analyte chemical sensor aims to transform subtle variations in multiple analytes’ physical or chemical properties into distinct output signals. Chemically responsive nanostructure array (nanoarray) promises as a competitive sensor platform due to its robust physical properties, tunable chemical composition, and high surface area for analyte interaction. Specifically, the well-defined size, shape, and tunable surface structure and properties make it feasible to develop either new sensing modes on single device or integrated multi-modular sensors. In conjunction with the well-developed resistor-type sensors and sensor arrays, the complementary utilization of and intercorrelation with the electrochemical, optical, voltammetry modes in the multi-modular sensing strategies could provide multi-dimensional measurements to different analytes in a complex mixture form, where species information could be accurately and robustly separated from spatially collective responses. This review intends to provide a survey of the recent progress on multi-analyte sensing strategies and their unique structure design, as well as the related sensing mechanics in interaction of analytes and sensitizer and the behind mechanism for analytes’ differentiation.

ZnO is attracting intensive attention for its versatile applications in transparent electronics, UV emitter, piezoelectric devices, chemical sensor and spin electronics. As one of the direct wide band gap semiconductors, it has advantages over GaN due to its larger exciton binding energy, better lattice match on heteroepitaxial growth and availability of single crystal substrate. Large effort has been invested in the growth of nanostructured ZnO to explore its potentials for nanoscale device applications. ZnO nanobelts, nanowires, nanorings, and nanohelixes demonstrate the diversity of ZnO nanostructures family. This review presents recent research on ZnO nanostructures. Issues of synthesis methods, optical, electrical, gas sensing and magnetic properties are summarized. These progresses constitute the basis for developing future applications in nanoscale electronics, optoelectronics, chemical sensor and spintronics.

This paper offers an analytical modeling of thin-filmed, multi-layer piezoelectric microcantilevers that are used as MEMS sensors. These sensors are chemical kind and use piezoelectric microcantilever. These types of microcantilevers are covered with variety of unique probe coating. The sensor has high sensitivity with external voltage measured in mV and uses PSD† system to indentify chemical ingredients of materials. The identification of the chemical ingredient of materials is based on change in angle of micro cantilever in the liquid or gas environment. The deflection of microcantilever results in varying voltage that can be used to analyze materials. Analytical simulation using Cosmol software and theoretical computations using equations will be offered in order to determine the parameters for optimal design setting. The analytical simulation includes design of mems and Cosmol software model development. The analytical model of the cantilever will be analyzed and the process of its construction will be discussed.