Reversible Multilevel Stimuli‐Responsiveness and Multicolor Room‐Temperature Phosphorescence Emission Based on a Single‐Component System

Abstract There are limited reports about the transformation of pure organic room‐temperature phosphorescence (RTP) materials with multilevel stimuli‐responsiveness at different RTP emission wavelengths under external stimuli. It is difficult to ensure efficient intersystem crossing (ISC) in different states of a single‐component system. This research reports the conversion of the organic single‐component small molecule 1,2‐bis(4‐alkoxyphenyl)ethane‐1,2‐dione ( N‐BOX ) with multilevel stimuli‐responsiveness between high‐efficiency blue and yellow RTP by grinding or thermal annealing N‐BOX crystals. The RTP emission of N‐BOX in the crystalline state was easy to adjust by external stimuli (grinding or thermal annealing) due to its non‐compact packing, which led to a phase transition and generated unique multilevel stimuli‐responsiveness. In particular, the RTP quantum yield of 7‐BOX with multilevel stimuli‐responsiveness reached 68.4 %, which provides an opportunity for regulation of smart optical materials based on pure organic RTP.