Topochemical Synthesis of Copper Phosphide Nanoribbons for Flexible Optoelectronic Memristors

Metal phosphide nanoribbons are suitable building blocks for flexible photoelectronic microdevices due to the special electronic structure, large contact area, and excellent mechanical properties. In this work, single-crystal copper phosphide nanoribbons (Cu₃P NRs) are prepared topochemically from crystalline red phosphorus nanoribbons (cRP NRs) to retain the cRP morphology. The Cu₃P NRs are used to construct flexible photoelectronic memristors on the ITO/PEN substrate with the native oxidized shell of Cu₃P NRs serving as the charge trapping layer to modulate the resistance switching characteristics. The Cu₃P NRs-based memristors have outstanding nonvolatile memory properties in different mechanical bending states and different bending times. Optically and electrically modulated artificial synaptic functions are observed from the Cu₃P NRs-based memristors and owing to the memory backtracking function, pattern recognition is achieved with the Ag/Cu₃P/ITO artificial synapse array. The topochemical synthesis method constitutes a universal approach to produce nanostructured compounds with an unusual morphology and specific crystalline orientation. The results also reveal that metal phosphides are excellent materials in memristors for future optoelectronic neuromorphic computing.