Conjugated polymers, applications

Gaylord BS, Massie MR, Feinstein SC, Bazan GC (2005) SNP detection using peptide nucleic acid probes and conjugated polymers applications in neurodegenerative disease identification. Proc Natl Acad Sci USA 102 34—39... 

Wu MW, Conwell EM (1998) Theory of photoinduced charge transfer in weakly coupled donor-acceptor conjugated polymers application to an meh-ppv cn-ppv pair. Chem Phys 227 11... 

A. Moliton, R. C. Hiorns, Review of electronic and optical properties of semiconducting pi-conjugated polymers applications in optoelectronics, Polymer International 2004, 53, 1397. 

Semi-conducting conjugated polymers (application as polymer light-emitting diodes, photovoltaic cells, sensors, field-effect transistors etc., e.g. poly(phenylene vinylene) (PPV)),... 

This polymerization strategy is extensively used for the synthesis of PPV and its substituted derivatives. Wessling and Zimmerman [38] developed a method for the synthesis of PPV via thermo-conversion of sulfonium intermediate (prepolymer) into PPV to yield its film. In the Wessling precursor route l,4-xylylene-bis-(dialkyl sulfonium)-dichloride is used which upon elimination of tetrahydrothiophene and HCl yields PPV polymer. Fig. 5. The thermo-conversion mechanism yields pin-hole free thin films of conjugated polymers applicable for PLED fabrication. The thermo-conversion temperatures can be lowered to as low as 100 °C using bromide derivatives which can help in the fabrication of flexible PLED devices. 

In low-dimensional systems, such as quantum-confined. semiconductors and conjugated polymers, the first step of optical absorption is the creation of bound electron-hole pairs, known as excitons [34). Charge photogcncration (CPG) occurs when excitons break into positive and negative carriers. This process is of essential importance both for the understanding of the fundamental physics of these materials and for applications in photovoltaic devices and photodctcctors. Since exciton dissociation can be affected by an external electric field, field-induced spectroscopy is a powerful tool for studying CPG. 

The rest of this chapter will focus primarily on results using the soluble PPV-based polymer MEH-PPV. The results obtained for MEH-PPV are typical of the conjugated polymers used in LEDs. The models and results presented are generally applicable. They describe the operation of a wide range of polymer LEDs if the appropriate polymer film properties arc used. 

Besides the necessity for improvement in efficiency, stability is another problem for all the applications of conjugated polymers. First experiences on conju-... 

For photovoltaic cells made with pure conjugated polymers, eneigy conversion efficiencies were typically I0 3-I0 1%, loo low to be used in practical applications [48, 63, 67]. Thus, pholoinduced charge transfer across a donor/acceptor... 

Polymers with n-conjugated backbones are an important class of materials that have captured the imagination of the scientific community due to their remarkable properties and exciting applications [91-95]. While most of the work on n-conjugated polymers has focused on all-carbon systems, there has been considerable interest in incorporating heteroatoms into the n-conjugated backbone (i.e.,polythiophene, polypyrrole, polyaniline) to tune their properties. 

Both theoretical and experimental evidence suggest that the precise nature of the charge carriers in conjugated polymer systems varies from material to material, and it is still a subject of debate in many cases. A discussion of the various theoretical models for the electronic structure of conjugated polymers is given below, using polyacetylene and poly(paraphenylene) as examples. More detailed information on these materials and the applicability of these theoretical models is given in subsequent sections. 

The electron delocalizing capability of a boron atom arising from its empty p-orbital positions it as an ideal candidate for incorporation in conjugated polymers for use in optical and sensing applications. The majority of the examples of boron-atom-containing conjugated polymers have been synthesized via the hydroboration reaction. However, other synthetic procedures have also been utilized. 

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