1 research outputs found
On the Morphology of a Discotic Liquid Crystalline Charge Transfer Complex
Discotic liquid crystalline (DLC) charge transfer (CT)
complexes, which combine visible light absorption with rapid charge
transfer characteristics within the CT complex, can have a great potential
for photovoltaic applications when they can be made to self-assemble
in a bulk heterojunction arrangement with separate channels for electron
and hole conduction. However, the morphology of some liquid crystalline
CT complexes has been under debate for many years. In particular,
the liquid crystalline CT complex built from the electron acceptor
2,4,7-trinitro-9-fluorenone (TNF) and discotic molecules has been
reported to have the TNF “sandwiched” either between
the discotic molecules within the same column or between the columns
within the aliphatic tails of the discotic molecules. We present a
detailed structural study of the prototypic 1:1 mixture of the discotic
2,3,6,7,10,11-hexakisÂ(hexyloxy)Âtriphenylene (HAT6) and TNF. Nuclear
magnetic resonance (NMR) line widths and cross-polarization rates
are consistent with the picosecond time scale anisotropic thermal
motions of the HAT6 and TNF molecules previously observed. By computational
integration of Rietveld refinement analyses of neutron diffraction
patterns with density experiments and short-range structural constraints
from heteronuclear 2D NMR, we determine that the TNF molecules are
vertically oriented between HAT6 columns. The data provide the insight
that a morphology of separate hole conducting channels of HAT6 molecules
can be realized in the liquid crystalline CT complex