Rectification modulation via interfacial noncovalent interactions between peptide self-assembled monolayers and...

Biomolecules have emerged as promising components for molecular devices owing to their structural diversity and functional versatility. Among biomolecules, peptides are particularly attractive because of their programmable sequences, tunable electronic properties, and ease of modification. However, the functionalities of peptide-only electronic devices remain limited, underscoring the need for new strategies to expand the scope and capabilities of these devices. Here, we constructed peptide/quantum dot (QD) bilayer heterojunctions by introducing a densely packed QD monolayer onto a uniform and well-ordered peptide self-assembled monolayer (SAM). By tuning the composition and length of the peptides, together with the surface ligands and size of the QDs, the rectification is enhanced through the peptide-QD interfacial interactions. The heterojunction exhibits a rectification ratio (RR) of up to 3.88 orders of magnitude. Notably, electrostatic interactions regulate interfacial charge transport more effectively than π-π interactions, leading to a more pronounced improvement in RR, with the highest increment reaching 3.13 orders of magnitude from the peptide-only to the peptide/QD junction. Bias-dependent impedance measurements and temperature-dependent electrical measurements collectively reveal that peptide-QD interfacial interactions modulate charge-trapping processes, reduce the interfacial transport barrier, and influence the energy-level alignment within peptide/QD heterojunctions. These findings deepen our understanding of biomolecule-inorganic interfacial interactions and provide a new strategy for developing peptide-based rectifiers.