Rectifications in organic single-molecule diodes alkanethiolate-terminated heterocyclics

• The organic single-molecule diodes S(CH2)11-terminated with bipyridyl and phenanthroline groups present rectifying effects.
• The S(CH2)11-terminated with phenylpyridyl exhibit the insulating character.
• The I–V curve of S(CH2)11-terminated with pyrazinyl group presents well linear character.

Based on the non-equilibrium Green's function formalism combined with the ab initio density functional theory, we investigate the rectifying behaviors of the organic single-molecule S(CH2)11-terminated with a variety of heterocyclics (i.e., BIPY, PHE, PHEPY, and PYR) coupled with two semi-infinite Au electrodes. Our quantum transport calculation results show that the BIPY and PHE nanojunctions show the high-efficiency rectifying effects. While, differently, the current–voltage (I–V) curves of PHEPY and PYR nanojunctions display the insulating and linear characters, respectively. The corresponding electronic transport mechanisms are analyzed in detail. Our calculation results demonstrate that these investigated organic single-molecule nanojunctions have the potential applications in rectifiers and molecular wires.