Visualization of exciton transport in ordered and disordered molecular solids

Publication Type:

Journal Article

Source:

Nat. Commun., nature.com, Volume 5, p.3646 (2014)

ISBN:

2041-1723

Keywords:

2014

Abstract:

Transport of nanoscale energy in the form of excitons is at the core of photosynthesis and the operation of a wide range of nanostructured
optoelectronic devices such as solar cells, light-emitting diodes and
excitonic transistors. Of particular importance is the relationship
between exciton transport and nanoscale disorder, the defining
characteristic of molecular and nanostructured materials. Here we report a
spatial, temporal and spectral visualization of exciton transport in
molecular crystals and disordered thin films. Using tetracene as an
archetype molecular crystal, the imaging reveals that exciton transport
occurs by random walk diffusion, with a transition to subdiffusion as
excitons become trapped. By controlling the morphology of the thin film,
we show that this transition to subdiffusive transport occurs at earlier
times as disorder is increased. Our findings demonstrate that the
mechanism of exciton transport depends strongly on the nanoscale
morphology, which has wide implications for the design of excitonic
materials and devices.