Toward a simple way for a mechanochromic luminescent material with high contrast ratio and fatigue resistance:...

In this work, we present the synthesis and photoluminescence (PL) behaviour of a new compound, DHNC. The molecular design includes twisted conformation and the incorporation of electron donor (D) and acceptor (A) pairs, which endows the compound with both twisted intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) properties. Importantly, the compound exhibits mechanochromic luminescence (MCL): The emission of the crystalline powder shows strong green emission but turns into orange-red with an obvious quenching effect after grinding, demonstrating a high contrast ratio. The emission of the ground sample can be rejuvenated though recrystallization by either immersion or fumigation in common organic solvents. The emission can be reversibly switched between two states for more than 10 cycles, showing fatigue resistance. In a quantitative mechanical experiment, the DHNC-loaded film has a remarkable emission loss with the external force up to 67.9 Mpa, showing high sensitivity. An archetype of information storage is developed based on this MCL material, which uses mechanical force to write information and organic vapour to erase. Letters and cartoon pictures can be written and erased repeatedly on the DHNC-loaded film, indicating high contrast ratio and fatigue resistance.