Intermolecular charge transport is crucial in π-conjugated materials but the experimental investigation remained challenging. Here, we show that charge transport through intermolecular and intramolecular paths in single-molecule and single-stacking thiophene junctions could be investigated using the mechanically controllable break junction (MCBJ) technique. We found that intermolecular charge transport ability through different single-stacking junctions is approximately independent of molecular structures, which contrasts with the strong length dependence of conductance in single-molecule junctions with the same building blocks, and the dominant charge transport path of molecules with two anchors transits from intramolecular to intermolecular paths when the conjugation pattern increased. The increase of conjugation further leads to higher binding probabilities due to the variation in binding energies supported by density functional theory (DFT) calculations. Our results demonstrate that intermolecular charge transport is not only the limiting step but also provides the efficient and dominate charge transport path at the single-molecule scale
