A Multi‐Stimuli‐Responsive Molecule with Responses to Light, Oxygen, and Mechanical Stress through Flexible Tuning of Triplet Excitons

Abstract Multifunctional stimuli‐responsive materials have attracted tremendous attention because of their great potential in a variety of applications. However, conventional stimuli‐responsive emitting materials are limited to single‐stimulus response with rare attention paid to triplet excitons controlling. Herein, a multi‐stimuli‐responsive molecule (SPh‐TP) with tuning of triplet excitons is reported. During illumination, the SPh‐TP crystals with unique twisted structure and loose packing have a high probability to contact with neighboring oxygen atoms, followed by the occurrence of triplet–triplet energy transfer, and thus showing a photosensitive property. Meanwhile, the photosensitive property is also observed for the crystalline sample in vacuum, which is associated with oxygens locked in crystal pores. Upon mechanical stress, the crystalline morphology is broken and the molecules become more planar with tighter stacking, revealing its mechanochromism. In comparison to the crystalline sample, the ground sample can respond to light with different rates depending on the ratio of oxygen. This multi‐stimuli‐responsive material shows potential applications in oxygen detection and double‐encryption of information.