Unsymmetric Benzo[b]phosphole-Fused Diarylethenes: From Enhanced Photochromic Behavior to Solution-Processable Photoswitchable Organic Resistive Memory Devices.

Several unsymmetric photoswitchable benzo[b]phosphole-fused diarylethenes have been synthesized. Compared with their symmetric counterparts, the photochromic properties of the unsymmetric benzo[b]phosphole-fused diarylethenes, including photocycloreversion efficiency, fatigue resistance, and thermal irreversibility, have been significantly enhanced. Through rational molecular design, the lowest-energy absorption band can be efficiently tuned. One derivative has served as the active component for the fabrication of optical memory storage, and two of them have been employed in the fabrication of photoswitchable organic resistive memory devices, which demonstrate low turn-on voltage, narrow operating bias, large ON/OFF ratio, and prolonged retention time. The devices exhibit distinctive resistive memory behavior in their open and closed forms.