Polymer light-emitting diodes principle

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. 

In this book the authors illustrate the basic physics and materials science of conjugated polymers and their interfaces, particularly, but not exclusively, as they are applied to polymer-based light emitting diodes. The approach is to describe the basic physical and associated chemical principles that apply to these materials, which in many instances are different from those that apply to the inorganic counterparts. 

In recent years, great progress has been achieved in the preparation of various types of polymer nanocomposites and in understanding the basic principles that determine their optical, electronic, and magnetic properties. As a result, nanocomposite-based devices such as light-emitting diodes (LEDs), photodiodes, and photovoltaic (PV) solar cells have been fabricated and their properties characterized. 

In parallel with these efforts to understand the underlying physics of conducting polymers, there are explosively increased activities in the research for applications of these materials in optoelectronic devices [4, 1169]. In particular, research in the use of these materials as the active electroluminescent media in light-emitting diodes (LEDs) has advanced rapidly after its first report in 1990 [134], and prototype devices now meet realistic specifications for applications. Therefore, we also make an attempt in this review to cover the basic principle of the polymer LED and current issues that determine the limits of device performance. 

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