Towards Optical Information Recording: A Robust Visible‐Light‐Driven Molecular Photoswitch with the Ring‐Closure Reaction Yield Exceeding 96.3 %

Abstract Diarylethene molecular photoswitches hold great fascination as optical information materials due to their unique bistability and exceptional reversible photoswitching properties. Conventional diarylethenes, however, rely on UV light for ring‐closure reactions, typically with modest yields. For practical application, diarylethenes driven by visible lights are preferred but achieving high ring‐closure reaction yield remains a significant challenge. Herein, we synthesized a novel all‐visible‐light‐driven photoswitch, TPAP−DTE, by facilely endcapping the dithienylethene (DTE) core with triphenylamine phenyl (TPAP) groups. Owing to the electron‐donating conjugation effect of TPAP, the open‐form TPAP−DTE responds strongly to short‐wavelength visible lights with considerable photocyclization quantum yields and molar absorption coefficient. Upon 405 nm visible‐light irradiation, TPAP−DTE achieves a ring‐closure reaction yield exceeding 96.3 % (confirmed by both nuclear magnetic resonance spectroscopy and high‐performance liquid chromatography). Its ring‐opening reaction yield is 100 % upon irradiation with long‐wavelength visible light. TPAP−DTE could be regarded as a bidirectional “quasi”‐quantitative conversion molecular switch. Furthermore, TPAP−DTE exhibits robust fatigue resistance over 100 full photoswitching cycles and great anti‐aging property under 85 °C and 85 % humidity for at least 1000 h. Consequently, its rewritable QR‐code, multilevel data storage, and anti‐counterfeiting/encryption applications are successfully demonstrated exclusively using visible lights, positioning TPAP−DTE as a highly promising medium for information recording.