Opto-electronic applications

R. Kern, N. van der Burg, G. Chmiel, et al., Long term stability of dye-sensitised solar cells for large area power applications, Opto-Electronics Review, vol. 8, no. 4, 284 pages, 2000. 

Metallo-organic CVD (MOCVD) is a specialized area of CVD, which is a relatively newcomer, as its first reported use was in the 1960s for the deposition of indium phosphide and indium anti-monide. These early experiments demonstrated that deposition of critical semiconductor materials could be obtained at lower temperature than conventional thermal CVD and that epitaxial growth could be successfully achieved. The quality and complexity of the equipment and the diversity and purity of the precursor chemicals have steadily improved since then and MOCVD is now used on a large scale, particularly in semiconductor and opto-electronic applications.91P1... 

Strontium titanate (SrTi03) has a large dielectric constant of 12, and a high refractive index with potential opto-electronic applications. It is deposited by MOCVD from titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Torr.t" " ... 

These materials are useful semiconductors and have a wide range of industrial applications, particularly in opto-electronics. One of their attractive features is the possibility of tailoring the band gap and the lattice constant in the ternary alloys by varying the composition. CVD is now a major production process of these materials. 

The many possible combinations of II-V and II-VI compounds allow the tailoring of electronic and opto-electronic properties to suit specific applications. Of particular importance is the control of the stoichiometry of the element involved. This is achieved by the proper handling of the MOCVD reactions. Being able to tailor the bandgap imparts great flexibility in the design of transistors and optoelectronic devices. 

Conceptually and synthetically more straightforward molecules can be prepared through incorporation of chromophores onto simple phosphine moieties. The phosphorus fragment can be used either to influence or to organise the n-con-jugated systems. This section will focus only on derivatives tailored in order to exhibit specific properties related to applications in NLO,opto-electronics or as sensors. 

Metal chalcogenide semi-conducting materials have found many applications in opto-electronic, solar cell and photovoltaic devices. Deposition of these materials can be achieved by a variety of techniques of which one of the most... 

Conductivity sensors are most commonly used for safety purposes in household appliances. Presence and absence of washing liquor, detergency, and water softener can be easily measured and proper operation ensured [71]. The various applications mainly differ by their design of electrode geometry and methods for electrical measurement. Due to the close relation between ionic conductivity and water hardness, the automatic water softener in an automatic dishwasher can be controlled by a conductivity sensor [72]. To isolate the transmission of the measured value from the process controller, the conductivity sensor could incorporate an opto-electronical coupling [73]. Thus, protective insulation of the electrodes in a washer-dryer could be ensured. 

The most convincing argument for using Si photodiodes in UV detection is the availability of strong expertise in electronic Si devices. Processing and performance of opto-electronic Si devices have been optimized for decades, and the UV-enhanced photodiode is a high-performance niche product that can be produced at a reasonable price, thanks to these efforts. Its probably most serious drawback is the necessity of using filters for visible-blind applications, which considerably increases the cost of sensors and reduces their otherwise optimum sensitivity. 

Polycrystalline GaN UV detectors have been realized with 15% quantum efficiency [4], This is about 1 /4 of the quantum efficiency obtained by crystalline devices. Available at a fixed price, however, their increased detection range may well compensate their lack in sensitivity. Furthermore, new semiconductor materials with a matching band gap appear as promising candidates for UV detection if the presumption of the crystallinity is given up. Titanium dioxide, zinc sulfide and zinc oxide have to be mentioned. The opto-electronic properties and also low-cost production processes for these compound semiconductors have already been investigated to some extent for solar cell applications [5]. 

The highly oriented molecules in thin organic films such as Langmuir-Blodgett (LB) films and self-assembled monolayers (SAM) [1] are essential for some molecular functions. Non linear optical and opto-electronic properties are two of the most important and interesting functions of these molecular assemblies. In the past more than thirteen years, simulation of the primary process of photosynthesis using such molecular assemblies and its application to molecular photodiodes [2,3] have been one of the main subjects of our laboratory. 

All the compounds of the family (Al, Ga, In)-(P, As, Sb) are semiconductors and are well-known electronic and opto-electronic materials. They are often indicated as 13-15 compounds meaning compounds formed by the combination of one element of the 13 th group with one of the 15 th of the Periodic Table. In the semiconductor nomenclature these compounds are also called III/V compounds on the basis of old conventions in numbering the groups of the Periodic Table. Several synthetic approaches to the preparation and purification of the compounds of this family have therefore been considered. A selection of these methods will be reported as an illustration of the variety of methodologies which find increasing applications in intermetallic and, more generally, in solid-state chemistry. 

Abstract This review highlights how molecular Zintl compounds can be used to create new materials with a variety of novel opto-electronic and gas absorption properties. The generality of the synthetic approach described in this chapter on coupling various group-IV Zintl clusters provides an important tool for the design of new kinds of periodically ordered mesoporous semiconductors with tunable chemical and physical properties. We illustrate the potential of Zintl compounds to produce highly porous non-oxidic semiconductors, and we also cover the recent advances in the development of mesoporous elemental-based, metal-chalcogenide, and binary intermetallic alloy materials. The principles behind this approach and some perspectives for application of the derived materials are discussed. 

The metal-ligand fragment L M, the number of carbon atoms x, and the substituents at the terminal sp -carbon may vary considerably and, correspondingly, the properties and reactivities. The early members of the series of cumulenylidene complexes (x=l, 2, 3 carbene, vinylidene and allenylidene complexes) have established themselves as invaluable building blocks in stoichiometric synthesis and as highly potent catalyst precursors. The higher members might potentially be very useful candidates for application as one-dimensional wires and in opto-electronic devices. 

Because of the limitations of both electronics and photonics a hybrid technology, opto-electronics, has been a major area of research since the 1980s, especially into the non-linear properties of molecules and their potential applications in communications, data storage and information processing. ... 

Chemical vapour deposition (CVD) is employed to prepare adherent films of controlled composition and thickness. Protective coatings, micro- and opto-electronics, ceramic fibres and ceramic-matrix composites production represent the usual applications of this technique, which allows surfaces of complex geometry to be uniformly coated. 

The branched polysilanes show a broad emission peak around 450 nm, where the large red shift in the fluorescence spectra is due to the influence of aryl substituents and the introduction of branched points. For (opto)electronic applications, the UV irradiation and thermal stability are crucial to device stability. Branched polysilanes have better thermostability and are more resistant to UV irradiation than are linear polysilanes. 

Applications of conjugated polymers-NCs hybrids in various (opto-)electronic devices and sensors require a deeper understanding of the relationship between their chemical and photophysical properties and their structure at different levels from the molecular to the bulk material. This requires the use of complementary methods... 

Tremendous efforts have been paid toward the development of new phthalocyanine molecular materials as well as toward their applications. Recent emphasis in both academic researches and technical field has been put on the design and synthesis of novel phthalocyanine species, the structure-property relationship, self-assembly properties, molecular electronics and opto-electronics, and dye-sensitized solar cells. Although excellent reviews and monographs about phthalocyanines were published several years ago, it is time to provide a survey of a number of new important developments in this fascinating area of phthalocyanine chemistry. The aim of this book is to bring both the academic and industrial researchers an easy way to the new progress of phthalocyanines made lately in related field. 

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