Interface Regulated Solid-State Rectification of Peptide via Quantum Dots Self-Assembly Monolayer.

Peptides have been demonstrated as promising candidates for constructing bioelectronic devices. The charge transport through peptides can be effectively modulated via intrinsic composition, structure, and, most notably, interfacial engineering. However, achieving specific electrical properties, such as solid-state rectification, remains a challenge in peptide-based bioelectronics. To fill this gap, a solid-state heterojunction is designed based on the uniform and densely-packed bilayers composed of peptide and quantum dots (QDs) self-assembled monolayer. The presence of a QDs monolayer markedly regulates the rectification and static dielectric constant (ɛr) of the peptide-based heterojunctions. The solid-state rectification ratio of peptide junctions can be raised up to ≈103, and the ɛr increases by a factor of 3. Both the rectification ratio and ɛr of peptide/QDs heterojunctions increase with enhanced non-covalent interactions between peptide side chains and QDs. The interfacial interaction modulates the coupling across the interface, influencing the energy level alignment at the peptide/QDs interface. This leads to distinct charge transport pathways under opposite bias polarities, thus achieving the regulation of rectification. These findings suggest that strengthening interfacial interactions can increase both rectification and ɛr. This deepens the understanding of interface-regulated molecular charge transport and offers a theoretical framework for optimizing the biomolecular solid-state rectification.