Lecture

Charges at Interfaces: Fermi-Dirac Distribution and Density of States

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In course

MSE-486: Organic electronic materials

This course will introduce students to the field of organic electronic materials. The goal of this course is to discuss the origin of electronic properties in organic materials, charge transport mechanisms, chemical synthesis, materials processing, and dev ...

Description

This lecture covers the Fermi-Dirac distribution for thermal distribution of electron energies, the concept of Fermi energy, and the density of occupied states in materials. It explains the differences in the Fermi level between metals, semiconductors, and insulators, and discusses the temperature-dependent density of occupied states in semiconductors. Additionally, it explores the behavior of ideal metallic electrodes in organic semiconductor devices, the role of electrode materials, and the mechanisms of charge injection. The lecture concludes with insights on band bending, activation energy barriers for charge injection, and the different methods of charge injection in organic semiconductors.

Instructor

Holger Frauenrath

Holger Frauenrath (born in Aachen, Germany) studied chemistry at RWTH Aachen , Germany from 1992 to 1997, with a focus on synthetic organic chemistry. He performed his PhD thesis from 1998 to 2001 in the research group of Prof Hartwig Höcker at RWTH Aachen, working on a project related to the stereospecific polymerization of methacrylates as well as their copolymerization with olefins using zirconocene catalysts. Holger Frauenrath then joined the group of Prof. Sam Stupp at Northwestern University , Evanston, IL, USA, as a postdoctoral fellow supported by a Feodor Lynen fellowship of the Alexander von Humboldt Foundation . His postdoctoral research projects were centered around the supramolecular self-assembly of rod-coil molecules. Holger Frauenrath returned to Germany in 2003 and started to build his own research group at FU Berlin, funded with an Emmy Noether Grant from the German Science Foundation . In 2005, the research group moved to the Department of Materials at ETH Zurich , Switzerland, where it became a scientifcally independent part of the Polymer Chemistry Group led by Prof. A. Dieter Schlüter . Holger Frauenrath obtained his Habilitation from ETH Zurich in 2009. In 2009, Holger Frauenrath has been appointed as a professor at the Institute of Materials (IMX) of the Ecole Polytechnique Federale de Lausanne (EPFL) , Switzerland, building the new Laboratory of Macromolecular and Organic Materials (LMOM) . In the same year, Holger Frauenrath was received the prestigious European Research Council (ERC) Starting Investigator grant.

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Solid-state physics

Related concepts (32)

Semiconductor

A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created.

Electronic band structure

In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called band gaps or forbidden bands). Band theory derives these bands and band gaps by examining the allowed quantum mechanical wave functions for an electron in a large, periodic lattice of atoms or molecules.

Doping (semiconductor)

In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic semiconductor. Small numbers of dopant atoms can change the ability of a semiconductor to conduct electricity. When on the order of one dopant atom is added per 100 million atoms, the doping is said to be low or light.

Fermi gas

A Fermi gas is an idealized model, an ensemble of many non-interacting fermions. Fermions are particles that obey Fermi–Dirac statistics, like electrons, protons, and neutrons, and, in general, particles with half-integer spin. These statistics determine the energy distribution of fermions in a Fermi gas in thermal equilibrium, and is characterized by their number density, temperature, and the set of available energy states. The model is named after the Italian physicist Enrico Fermi.

Semiconductor device

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum (typically liberated by thermionic emission) or as free electrons and ions through an ionized gas.

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