Coherent electron transport through multiple π-π stacked benzene rings

Abstract

Charge transport through π–π stacking is vital for electron transport in doped conducting polymers. Multiple π–π-stacked benzene rings were constructed using ethylene bridges, as in [2,2]-paracyclophane, and charge transport across the benzene rings was observed using a scanning tunneling microscope (STM) break-junction technique. In this study, molecular models of stacked benzene rings were constructed, and electron transport was examined using the Landauer model based on first-principles methods. The conductance of the molecule optimized in the charged state increases by approximately 10 times compared to that in the neutral state. Although it should be noted that these calculations concern the electrical conduction of neutral molecules using the chemical structure in the cationic state, the coherent electron transport through π–π stacking, optimized in the charged state, is not predicted to increase significantly. This study provides a guideline for understanding the electrical conduction mechanism in π-conjugated conducting polymers.