Controlling the efficient and ultralong room-temperature phosphorescence of 9H-dibenzo[a,c]carbazole derivatives for erasable light printing†

The development of intelligent polymer materials with high phosphorescence quantum yields (Φ_phos.) and ultralong phosphorescence lifetimes (τ_phos.) simultaneously under ambient conditions is significant but very challenging. In this work, two new organic luminogens, namely BCzS and BCzSF, were synthesized by attaching dibenzothiophene and diphenyl sulfone to the nitrogen atom of 9H-dibenzo[a,c]carbazole via a palladium-catalyzed carbon-nitrogen coupling reaction, respectively. Subsequently, they were employed as guest compounds and doped into the mixtures of bisphenol A diglycidyl ether and 1, 3-propylenediamine, respectively, followed by an in situ polymerization to produce doped epoxy polymer (EP) films BCzS-EP and BCzSF-EP. It was found that the resulting polymer films showed high Φ_phos. and τ_phos. values of up to 13.5% and 3.01 s, respectively, and could produce conspicuous green organic afterglow with a duration time of over 20 s under ambient conditions. Moreover, the BCzS-EP and BCzSF-EP films exhibited controllable and reversible photoactivated UOP properties, in which their organic afterglow could be facilely turned on and off by the stimuli of light and heat. Given the unique photophysical properties and excellent flexibility and transparency, the BCzSF-EP film was successfully used for erasable light printing. This work provides a new direction for developing intelligent and flexible polymer materials simultaneously with high Φ_phos. and τ_phos. values.