Multicolor ultralong room-temperature phosphorescence from pure organic emitters by structural isomerism

The current research of ultralong room-temperature phosphorescence (RTP) materials is mainly focused on the lifetimes and efficiencies. The tuning of emission colors is in high demand for various potential applications in optoelectronics, however the corresponding research lags behind. Herein, we report three ultralong RTP molecules based on the carbazole and chromone units through isomerization engineering. By adjusting the linking positions of the carbazole substituents, the ultralong RTP emission can be tuned from blue to red band along with lifetime variation. Detailed experimental and theoretical investigations reveal that the changeable emission color emerges from the mixing of multiple phosphorescence bands and have great relation to the stacking of carbazole and chromone chromophores. These materials were used to construct anti-counterfeiting patterns with diverse afterglow emission colors, presenting a promising application potential in the field of information security.