Controllable co-assembly of organic micro/nano heterostructures from fluorescent and phosphorescent molecules for dual anti-counterfeiting†
Organic micro/nano heterostructures composed of multi-materials provide an ideal system to develop molecular engineering, optoelectronics and encryptions. However, current organic heterostructures are mostly based on fluorescent dyes, which limits their diversification applications. Here, two types of branched organic heterostructures (BNwHs) were prepared by the co-assembly of one fluorescer and one metal-free organic phosphor. By adjusting the concentration of the two components, we constructed their heterojunctions with a fluorescent or phosphorescent molecular backbone, respectively. The molecular co-assembly mechanism in relation to lattice matching was elaborated from the in situ observation of the assembly process combined with the molecular arrangement at the junctions. With large discrepancy in emission lifetimes and excitation-dependent emission, these heterostructures were used for dual anti-counterfeiting applications.