Low-temperature field effect in a crystalline organic material

Molecular organic materials offer the promise of unique electronic devices but also present challenges for understanding charge transport in narrow-band systems. Low-temperature studies elucidate fundamental transport processes. We report the lowest-temperature field-effect transport results on a crystalline oligomeric organic material, rubrene. We find field-effect switching with an on-off ratio up to ${10}^{7}$ at temperatures down to $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Gated transport shows a factor of $\ensuremath{\sim}10$ suppression of the thermal activation energy in the $10--50\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ range and nearly temperature-independent resistivity below $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.