Optical light emitting diodes-physical

Optical properties light-emitting diodes, resonance absorption of near IR-radiation Physical and chemical properties large specific surface and possibihty of surface chemical modification, adsorbents, catalysts, chemical sensors, materials for electrodes, chemical batteries, fuel elements and super condensers. 

Device motivation for interface studies, and Optical absorption and emission in conjugated oligomers and polymers. The principles of device physics of metal insulator field-effect transistors (MISFETs) and light emitting diodes (LEDs) are oudined mainly as motivation for the contents of the chapters which follow, but also to point out certain features relevant to developing an understanding of the nature of the polymer-metal interface (chapters 5 and 6). The basic principles of electro-luminescence are reviewed here, at the level consistent with the aims of this work. 

The physical mechanism by which semiconductor light-emitting diodes (LEDs) emit light is spontaneous recombination of electron-hole pairs and simultaneous emission of photons. The spontaneous emission process is fundamentally different from the stimulated emission process occurring in semiconductor lasers and superluminescent LEDs. The characteristics of spontaneous emission that determine the optical properties of LEDs will be discussed in this section. 

The development of semiconductors is clearly among the most significant technological achievements to evolve from the study of solid-state chemistry and physics. Aside from their well-known applications in computers and electronics, semiconductors are also used in a wide variety of optical devices such as lasers, light-emitting diodes, and solar panels. The diversity of applications can be readily understood with only a basic understanding of the theory behind these materials. 

One active area of research is completely missing. These are the optical and electrical properties, with effects such as the high conductivity of doped conjugated polymers, electro-luminescence in polymeric light emitting diodes, or the ferro- and piezoelectricity of poly(vinylidene fluoride), to cite only a few examples. There is no good reason for this omission, only that I did not want to overload the book with another topic of different character which, besides, mostly employs concepts which are known from the physics of semi-conductors and low molar mass molecules. 

The commercial application of polymer blend technology has grown significantly such that, today, compositions are available with properties that once were substantially unattainable with homopolymers. To date, polymer blends have been applied in optical fibers [13,14], microlenses [15], liquid crystal display components [16,17], solar cells [18-20], nonionizing radiation detection [21] and polymer light-emitting diodes [22-24]. In particular, the use of developed polymer blends in optoelectronics applications appears unlimited. Polymer blends may also provide model systems in statistical physics when studying the fundamental aspects of equilibrium and nonequilibrium properties [3], optical properties [25], and mechanical and electrical properties [26]. 

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