Semiconductors organometallic polymers

Many of the organometallic polymers are semiconductors with bulk resistivities in the range of 10 —10 ° O-cm suitable for specific semiconductor use. Further, some exhibit interesting photo properties. 

The first symposium on Organometallic Polymers, held at the National Meeting of the American Chemical Society in September 1977> attracted a large number of scientists interested in this field, both established investigators and newcomers. Subsequent symposia in 1977, 1979, 1983, and 1987 have seen the field mature. Hundreds of papers and patents have been published. Applications of these materials as semiconductors and one-dimensional conductors, as radiation shields or as photo-resists, as catalysts, as controlled release agents for drugs and biocides and a wide variety of applications have been studied (see Chapter 1). 

The palladium-calalyzed polycondensation of 1,4-diethynylbenzene complex with 3-alkyl-2,5,-dibromothiophenes (scheme 23) was recently reported. These polymers displayed number-average molecular weights ranging from 13,000 to 24,400, with PDI ranging from 3.2 to 3.6. These organometallic polymers 80 exhibited a red shift of approximately 50 nm, indicating the n-delocalization in the backbone. The undoped polymer displayed semiconductor properties with a conductivity of 8.1 Xl0 S/cm. 

Several synthetic methods for the preparation of semiconductor nanoparticles have been reported. Colloidal and organometallic routes have probably been identified as the two major methods in use [11-16], although nano dimensional particles have been also synthesized in confined matrices such as zeolites [17], layered solids [18], molecular sieves [19,20], vesicles/micelles [21,22], gels [23,24], and polymers [25]. An ideal synthetic route should produce nanoparticles which are pure, crystalline, reasonably monodisperse and have a surface which is independently derivatized. 

Develop new electrode materials and the modification of electrode surfaces by investigation of conductive polymers, organometallic conductors and semiconductors, and the phenomena of absorption and covalent attachment... 

In general, two basic routes have been used to synthesize the composites. One is to carry the inorganic reaction between metal ion sources with H2S or organometallic sulphur sources inside the polymer matrices. The other is to polymerize the monomer after doping the inorganic semiconductor components inside. In the above traditional methods, the dispersion of metal sulphide is difficult to control since the inorganic reaction and polymerization are performed separately, and semiconductors could not be well dispersed in the polymer matrix. 

The cryochemical vapor deposition synthesis of metal-polymer films (from the gaseous state to the solid polymer one, bypassing the liquid phase) allows the production of both new organometallic structures and new valuable composites with high concentrations of nano-sized metal or semiconductor particles. 

Organometallic and inorganic polymers have frequently been investigated as possible conducting polymers. An early trick was to look for extended conjugation and then introduce mixed valence states. This most often led to charge-hopping type semiconductors. Thus, both poly(ferrocenylacetylene) and poly(vinyl-... 

P.-T. Wu, T. Bull, E S. Kim, C. K. Luscombe, S. A. Jenekhe, Organometallic Donor-Acceptor Conjugated Polymer Semiconductors Tunable Optical, Electrochemical, Charge Transport, and Photovoltaic Properties. Macromolecules 2009,42, 671-681. 

Examples in four different areas of zeolite inclusion chemistry will be discussed in the following. Noble metal and semiconductor clusters, organometallics, and intrazeolite polymer filaments are objects of new and continued research activity. 

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