Abstract
The performance of many emerging electronic and optoelectronic devices based on organic and nanoscale carbon semiconductors can be fine-tuned by control of the charge carrier density injected by redox dopants. We have recently demonstrated that the chemical structure (size, shape, and redox properties) of the dopant counterion has a significant influence on the electrostatic interactions with the charge carrier, which affects charge (de)localization and transport. We have exploited this to enhance the thermoelectric properties of thin film networks of single-walled carbon nanotubes (SWCNTs) and have observed strong modulation of the complex dielectric properties of isolated SWCNTs dispersed in a low dielectric solvent. Here we extend these studies to the redox doping of graphene nanoribbons (GNRs). We once again show that the chemical structure of the dopant counterion has a critical influence on the properties of the injected charge carriers. Large, spherical dopant counterions based on bulky benzyloxy-substituted icosahedral dodecaborane cluster dopants, DDBs, lead to enhanced delocalization of charge carriers and transport, as observed by UV-Vis-NIR / Fourier Transform Infrared (FTIR) spectroscopy and microwave conductivity, respectively. In contrast, the increased electrostatic interactions with the planar dopant counterion 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) results in stronger carrier localization, inhibiting transport. We will provide a comparison of the doping of GNRs, with SWCNTs and conjugated polymers.
Published Version
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