Achieving Sprayable Narrowband Blue Afterglow through Host‐Guest Strategy

ABSTRACT It is of great significance but remains formidably challenging to achieve the facile preparation of afterglow materials with narrow‐band emission and high color purity in the field of optoelectronics. Herein, a strategic method for constructing narrowband afterglow emission is presented by selecting multiple resonance (MR) narrowband thermally activated delayed fluorescence (TADF) molecule LM‐1 of indolo[3,2,1‐ jk ]carbazole (ICz) derivative as guest and rigid matrix of dimethyl terephthalate (DTT) as host. The afterglow emission can be easily achieved by spraying the LM‐1@DTT dichloromethane solution ink onto any substrate. With the assistance of DTT, the prepared materials unlock unprecedent narrowband blue afterglow emission with full width at half maximum (FWHM) of 28 nm and lifetime of 186 ms. Experimental studies reveal that the TADF mechanism and the low k RISC of 6.33 s −1 is the source of the afterglow. Given that the advantages of facile preparation and narrowband afterglow emission, it is successfully demonstrated that LM‐1@DTT materials can be applied in pattern spraying, information recording, and anti‐counterfeiting. This finding not only provides profound insight into how host‐guest doping modulates photophysical properties but also develop an extremely facile spray‐coated method for construction afterglow emission with low cost.