BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Charge transport in supramolecular assemblies: An atomistic descri
 ption - Dr. Jerome Cornil\, Universite de Mons-Hainaut\, Belgium
DTSTART:20090217T143000Z
DTEND:20090217T153000Z
UID:TALK15796@talks.cam.ac.uk
CONTACT:Dr. Z Chen
DESCRIPTION:Charge transport plays a key role in defining the performance 
 of organic-based devices such as light-emitting diodes\, solar cells\, or 
 field-effect transistors. Transport is typically described in two extreme 
 cases\, namely the band regime versus the hopping regime. I will argue in 
 the first part of the talk that many electronic effects in organic semicon
 ductors tend to favor a hopping picture in devices at room temperature. In
  this context\, macroscopic models have been developed over the years to c
 haracterize the influence of several parameters (such as temperature\, ele
 ctric field amplitude\, disorder\, charge carrier density) on the mobility
  values. Most of them have in common to involve effective parameters that 
 do not take fully into account the nature and relative position of the int
 eracting molecules. On the other hand\, quantum-chemical calculations have
  been extensively used recently to calculate all parameters governing the 
 rate of charge transfer between two interacting molecules in the hopping r
 egime\; such an approach explicitly takes into account the chemical struct
 ure and actual packing of the molecules. I will survey some of our recent 
 studies aiming at the description of the various transport parameters in a
  large variety of systems. I will also show that a bridge can be establish
 ed between the molecular and macroscopic worlds by performing Monte-Carlo 
 (MC) simulations based on the calculated transfer rates to be in position 
 to evaluate charge mobility within the hopping regime in supramolecular as
 semblies from calculated molecular parameters\; recent applications of thi
 s approach will be shown\, for instance to characterize the anisotropy of 
 charge transport in molecular crystals or the electric-field dependence of
  the mobility. Such simulations are typically performed nowadays on frozen
  structures\, thus neglecting the impact of lattice dynamics. In the last 
 part of the talk\, I will show very recent results examining the way inter
 molecular vibrations modulate the key transport parameters and I will disc
 uss the implications for charge transport properties. \n\n
LOCATION:Kapitza Building Seminar Room\, Cavendish Laboratory\, Department
  of Physics
END:VEVENT
END:VCALENDAR