Intermolecular hydrogen bond and π-π stacking improve electron mobility of phenanthroline-based electron-transporting materials

Abstract

A series of new ETMs are theoretically designed by introducing phthalimide or naphthalimide groups into the phenanthroline based on the experimentally ETM β-BNPhen. The electronic and electron transport properties are investigated through Quantum-chemical calculations. Results show that the new ETMs exhibit much better than β-BNPhen due to the excellent electron transport properties, transparency and solubility. Since the extra intermolecular hydrogen bond and π-π stacking in molecular stacking models, the electron mobility of all new ETMs is three orders of magnitude higher than that of β-BNPhen facilitating electron transport effectively. Additionally, the γ-positions of the imide in the phthalimide or naphthalimide groups are more conducive to electron transport, which leads to higher electron mobility compared with α and β-positions. These novel electron transporting molecules may provide a useful design strategy for efficient ETMs and be applied in devices such as organic OLEDs and solar cells.