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Lecture Peter A. Bobbert


25 November 2004 FWN-Building 5118.-156, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Peter A. Bobbert
Affiliation: Group Polymer Physics and Dutch Polymer Institute, Technische Universiteit Eindhoven
Title: Nature and transport of excitations in organic-electronic materials
Date: Thu Nov 25, 2004
Start: 14.00
Location: FWN-Building 5118.-156
Host: J. Knoester
Telephone: +31 50 363 4369


The nature and the transport of excitations in materials used in organic electronics are very different from those in inorganic materials used in conventional electronics. Many fundamental questions are still unanswered and progress requires substantial basic research efforts. This presentation focuses on theoretical research efforts to clarify a few of these fundamental questions.

(1) In the first part, I focus on the nature of excitations in conjugated polymers as calculated by first-principles Green-function techniques. The effect of dielectric screening on the excitations is shown to be vital in order to get their properties right, whereas the inclusion of solid-state effects worsens the agreement with most experiments.

(2) In the second part, I present a new theory for the nature and transport of polarons in organic crystals. The parameters in this theory are calculated from first-principles density-functional calculations. An application to naphthalene crystals reproduces all qualitative features of the measured temperature dependence and anisotropy of the electron- and hole-polaron mobilities.

(3) In the third part, I consider charge transport in disordered polymers by means of a numerically exact solution of the Pauli Master-equation, describing hopping motion in a disordered energy landscape. From this solution, the temperature, carrier density, and electric-field dependence of the charge-carrier mobility is obtained. With this information, current-voltage characteristics of polymer diodes are calculated and excellent agreement is found with experimental characteristics.

Last modified:22 October 2012 2.30 p.m.