90% Yield Production of Spiropyran Covalently Grafted MXene-Based RRAM Devices for Optoelectronic Dual-Response Switching

Over the past decade, great efforts have been devoted to both intellectual property protection and information security protection. As a promising electroactive material, MXene is covalently or non-covalently functionalized with organic species/polymers to produce a large amount of novel functional materials for biomedicine, optoelectronics, and energy storage. By using spiropyran covalently functionalized MXene (MXene-SP) as an active material, an optoelectronic dual-response resistive random access memory (RRAM) device is successfully fabricated. Upon UV illumination, the active layer is changed from MXene-SP (SP: ring-closed spiropyran form) observed under the illumination of blue light to MXene-MC (MC: ring-opened merocyanine form) due to photo-induced "close-to-open" isomerization. The as-fabricated ITO/MXene-SP/ITO device exhibits typical nonvolatile optoelectronic dual-response RRAM performance, with a production yield exceeding 90%. The achieved switch-on/off voltages are -1.25/2.07 V under the illumination of blue light and -0.58/0.91 V under UV illumination. The switching bias window (Delta|VON - VOFF|) and the ON/OFF current ratio of MXene-MC are 44.9% and 14.7% of these of MXene-SP, respectively. By utilizing the window difference between the RRAM performance achieved under the illumination of different lights, one can easily encrypt the quick response code. By using 4-bromophenyl-functionalized MXene as a 2D template, a highly soluble spiropyran covalently grafted MXene (MXene-SP) is synthesized. The as-fabricated ITO/MXene-SP/ITO device exhibits typical nonvolatile optoelectronic dual-response resistive random access memory performance, with a production yield exceeding 90%.image