ABSTRACT
Organic electronics, which is a vibrant field of research spanning physics, chemistry, material science, engineering, and technology, has long been a subject of immense interest due to the realization that Si electronics would reach the physical limits very soon [1]. A few major breakthroughs, particularly the realization of moleculebased conductors, together with the miniaturization of devices from microscale to nanoscale and the discovery of electroluminescence, which opens the way for the fabrication of light-emitting diodes, have further fueled interest in this area of research. The main challenge in the field of organic electronics is to design efficient optoelectronic devices by making use of organic materials, instead of traditional
8.1 Introduction to Organic Materials ................................................................ 163 8.2 Charge Carrier Mobility (μ).......................................................................... 164 8.3 Band Model................................................................................................... 165 8.4 Hopping Model ............................................................................................. 166 8.5 Theoretical Formalism ................................................................................. 166
8.5.1 Reorganization Energy ..................................................................... 167 8.5.2 Transfer Integral ............................................................................... 168
8.5.2.1 Dimer-Splitting Method ..................................................... 168 8.5.2.2 Fragment Orbital Approach ............................................... 168
8.5.3 Estimation of Mobility ...................................................................... 169 8.6 Calculations on Organic Molecular Solids ................................................... 170
8.6.1 Mobility in Polymorphs of Benzene and Naphthalene ..................... 170 8.6.2 Mobility in Octathio[8]circulene: Sulflower ..................................... 175
8.7 Conclusions and Future Directions ............................................................... 178 Acknowledgments .................................................................................................. 179 References .............................................................................................................. 179
inorganic materials. Organic materials are emerging as promising candidates for the fabrication of various electronic devices, such as light-emitting diodes [2-4], field-effect transistors [5,6], solar cells, and photovoltaic [7,8]. In these materials, the overlap of unhybridized pz orbitals form extended conjugation with delocalized π-electrons. The interplay between the π-electron and the geometric structure in conjugated materials uncovers a rich variety of new concepts, giving rise to many fascinating properties [8,9]. Owing to many attractive features, such as ease of synthetic modification, fabrication, processing, and fine-tuning, these π-conjugated materials exhibit potential advantages over inorganic materials and have become active elements for many electronic devices.
