Theoretical study on junctions in porphyrin oligomers for nanoscale devices

A unimolecular rectifier could be built by combining two molecular sub-units that contain acceptor or donor groups. Porphyrin possesses good electron-donating properties due to its large, easily ionized, π-conjugated system. In this study, we propose that a rectifier diode could be created by combining two metal porphyrin molecules containing different metal atoms. This function would realize an effect similar to a p–n junction in a solid-state device. A Zn porphyrin–Ni porphyrin junction in a non-conjugated porphyrin system displays a localization of frontier orbitals that is similar to a rectifier function.