Pressure-induced room-temperature phosphorescence enhancement based on purely organic molecules with a folded geometry.

The pressure-dependent luminescence behavior of purely organic compounds is an important topic in the field of stimulus-responsive smart materials. However, the relevant studies are mainly limited to the investigation of fluorescence properties, while room-temperature phosphorescence (RTP) of purely organic compounds has not been investigated. Here, we filled in this gap regarding pressure-dependent RTP by using a model molecule selenanthrene (SeAN) with a folded geometry. For the first time to the best of our knowledge, a unique phenomenon involving pressure-induced RTP enhancement was discovered in an SeAN crystal, and an underlying mechanism involving folding-induced spin-orbit coupling enhancement was revealed. Pressure-induced RTP enhancement was also observed in an analog of SeAN also showing a folded geometry, but in this case yielded a white-light emission that is very rare in purely organic RTP-displaying materials.