Light-Tunable Nonvolatile Memory Characteristics in Photochromic RRAM

Light-tunable resistive switching (RS) characteristics are demonstrated in a photochromophore (BMThCE)-based resistive random access memory. Triggered by nondestructive ultraviolet or visible light irradiation, two memory-type RS characteristics can be reversibly modulated in the same device upon a narrow range of applied voltage (<6 V), accompanied by the photochromophores in the active layer reversibly changed between ring-open state (namely, o-BMThCE) and ring-closed state (namely, c-BMThCE). The o-BMThCE-based memory exhibits a write-once-read-many characteristic with a high current on/off ratio of 10⁵, while the c-BMThCE-based one shows a flash characteristic. Both of the RS characteristics present good nonvolatile stability with the resistance states maintained over 10⁴ s without variation. This RS modulation is possibly related to the formation and rupture of conductive filaments, which formed along channels consisting of BMThCE trapping molecules. This work provides a new memory element for the design of light-controllable high density storage and data encryption technology.