Resonant tunneling transport in highly organized oligoacene assemblies

Electronic structure and transport properties of low dimensional organic systems have been theoretically investigated. On isolated molecules, a drastic decrease of the band gap by more than 4.5 eV is observed in acene molecules containing up to 15 members rings. The additional band gap decrease observed upon molecular assembling does not depend on the nature of the molecules but more on the separation between them. Oligoacene assemblies with intermolecular spacing dmol ⩽ 3.8 Å are characterized by an improved π-electron coupling that facilitates the electrical transport through resonant tunneling mechanism. For such molecular arrangement, we have computed significant band dispersion (≈340 meV), high transmittance (T¯(E)∼1), and relatively high mobility for holes and electrons (0.1–0.9 cm2/V s) in both resonant π-valence and π∗-conduction bands.