| Abstract: | Herein, two molecules based on urea and thiourea, which differ by only a single atom, were designed, successfully synthesized, and fabricated into resistive random‐access memory devices (RRAM). The urea‐based molecule showed binary write‐once‐read‐many (WORM) storage behavior, whereas the thiourea‐based molecule demonstrated ternary storage behavior. Atomic‐force microscopy (AFM) and X‐ray diffraction (XRD) patterns show that both molecules have smooth morphology and ordered layer‐by‐layer lamellar packing, which is beneficial for charge transportation and, consequently, device performance. Additionally, the optical and electrochemical properties indicate that the thiourea‐based molecule has a lower bandgap and may be polarized by trapped charges, thus the formation of a continuous conductive channel and electric switching occurs at lower bias voltage, which results in ternary WORM behavior. This study, together with our previous work on single‐atom substitution, may be useful to tune and improve device performance in the future design of organic memory. |
