posted on 2024-01-04, 14:35authored byDuyen
K. Tran, Sarah M. West, Jiajie Guo, Shinya E. Chen, David S. Ginger, Samson A. Jenekhe
Most
currently known n-type conjugated polymers have a semiflexible
chain topology, and their charge carrier mobilities are known to peak
at modest chain lengths of below 40–60 repeat units. Herein,
we show that the field-effect electron mobility of a model n-type
conjugated polymer that has a rigid-rod chain topology grows continuously
without saturation, even at a chain length exceeding 250 repeat units.
We found the mechanism underlying the novel chain length-dependent
electron transport to originate from the reduced structural disorder
and energetic disorder with the increasing degree of polymerization
inherent to the rigid-rod chain topology. Furthermore, we demonstrate
a unique chain length-dependent decay of threshold voltage, which
is rationalized by decreased trap densities and trap depths with respect
to the degree of polymerization. Our findings provide new insights
into the role of polymer chain topology in electron transport and
demonstrate the promise of rigid-rod chain architectures for the design
of future high-mobility conjugated polymers.