Ternary composite fluorescent films with tunable color and long lifetime based on efficient TS-FRET

Abstract

Multi-color long-wavelength organic afterglow materials are of great significance in anti-counterfeiting, but their preparation is still challenging. In this paper, a series of room temperature phosphorescence (RTP) films were constructed with polyvinyl alcohol (PVA) as rigid matrix and 9,10-diaminophenanthrene (DAphe) as guest molecule. Surprisingly, by adjusting the doping content of DAphe, their RTP emission peak width could be adjusted accordingly, and the lifetime was up to 3.25 s. Their dopant content dependent and excitation wavelength dependent luminescence characteristics and theoretical calculation results indicated that the observed broad emission peaks of RTP might be attributed to multiple luminescence centers generated by the aggregation of guest molecules. Interestingly, by doping several suitable fluorescent dyes screened as energy acceptors, multi-color, long-lasting afterglow composite films from blue to red were obtained, achieving 0.42 s delayed fluorescence at 661 nm with a fluorescence quantum yield of 32.22 %. In addition, these adjustable afterglow materials had good molding processability, so several cryptographic patterns were achieved to demonstrate their good application prospects in advanced anti-counterfeiting technologies.