Phthalocyanine-based molecular memristor consisting of a tin-bridged heterojunction

Molecular memristive devices are attractive for nanoscale memory and logic because their resistance can be modulated and retained through electrically addressable molecular states. Herein, we design a phthalocyanine-based molecular memristor constructed with a Cu/SnPc/graphene heterojunction. The SnPc molecule possesses two stable structural conformations, namely Sn-up and Sn-down orientations, which are reversible and switchable via pulsed current stimulation. In the Sn-up conformation, the electronic properties of the heterojunction are primarily governed by interlayer van der Waals interactions. In contrast, the Sn ion in the Sn-down conformation serves as a conductive bridge between the Cu electrode and phthalocyanine layer, which markedly diminishes the interlayer tunneling barrier. Cross-plane charge transport calculations demonstrate that the Sn-down configuration delivers a much higher current density compared with the Sn-up counterpart. These results suggest that a SnPc-based vertical heterojunction may provide a useful molecular building block for future memristive devices, while device-level neuromorphic or in-memory computing functions remain to be demonstrated.