Enhanced MoS ₂ heterojunctions by interface engineering with self-assembled monolayers

Functionalization with self-assembled monolayers (SAMs) can effectively modulate the interface properties between metal and molybdenum disulfide (MoS₂), thereby influencing the electrical and optoelectronic properties of the materials. However, the impact of molecular groups other than dipole moments on the interface requires further investigation. In this work, we selected a series of thiol molecules with different terminal groups but similar dipole properties to regulate the MoS₂ heterojunctions. The resulted rectification ratio of the heterojunctions could vary across 4 orders of magnitude and the photo response time decreased from 95 s to near 20 ms. The interlayered molecules do not only alter the rectifying behavior but also regulate the photo response speed, through the modulation of the interfacial band alignment and the reduction of the trapping states. This interface engineering approach allows for precise control over the charge carrier transport, ultimately enhancing the electrical and optoelectronic properties of the molecular heterojunctions.