Hi friends,
There is a special group seminar today at 3pm in the Division Room, from Professor Alex
Briseno. Title and abstract below.
Crystal Chemistry, Molecular Order and Charge Transport at Organic Semiconductor
Interfaces
Alejandro L. Briseno
University of Massachusetts- Amherst, Polymer Science and Engineering
Abstract
The exploration and understanding of the crystallization, growth and the orientation of
organic molecules on substrates is a very important feature in fundamental as well as
applied research in the various fields of organic electronic device research. It is well
known that the ordering and orientation of organic molecules significantly affects the
electronic structure and transport properties, and the anisotropy of the transport
properties in organic semiconductor thin films in particular has to be taken into account.
It is, however, not only the orientation of the film as a whole that is important, but the
molecular orientation in the few layers near an interface to other device layers that may
affect the electronic properties, such as the electronic trap states, contact resistances
or interface dipoles.
In this lecture, I will discuss our efforts in investigating charge and
photogenerated transport at organic nanocrystalline interfaces. For example, we have
synthesized single-crystalline donor-acceptor nanowire devices (i.e. transistors,
solar-cells) that have enabled us to demonstrate excitonic charge splitting and ambipolar
charge transport at p-n nanointerfaces. The use of organic single-crystalline devices will
have a major impact in accelerating the emerging area of organic electronics, as these
highly ordered systems will enable one to extract intrinsic charge carrier transport
phenomena that cannot be accurately determined from disordered systems common to amorphous
and/or polycrystalline films used in mainstream devices.
Figure. SEM image of vertically oriented crystals grown on graphene. The inset shows the
theoretically predicted growth morphology of a single crystal.
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