Photonic crystal induced multi-color luminescence of one AIEgen and its dual-mode anticounterfeiting application

Abstract

The aggregation-induced emission luminogens (AIEgens) have attracted extensive attention and have been rapidly applied in various fields, such as optical sensors, display, and bioimaging. Usually, AIEgens present a broad-band emission and are potential to obtain multi-color luminescence by separating and filtering partial emission ranges, which will make one AIEgen emit different colors. Here, photonic crystal (PC) structures are employed as tunable filters to construct AIEgens-embedded luminescent PCs (LPCs) with variable color outputs. The designed LPC structure consists of polystyrene (PS) spheres and TVP AIEgens. By matching the photonic band gaps (PBG) of PCs with the emission band of AIEgens, the full width at half maximum can be reduced and the emission wavelength becomes tunable. Based on the changeable PBGs of PCs which can be controlled by the lattice constant, the TVP AIEgens are combined with PCs built by PS spheres with diameters of 230, 254, and 273 nm to fabricate LPCs. As a result, red, green, and yellow emission colors were realized respectively under the same viewing angle (0°). Moreover, owing to the angle-dependence of PBG, the emission color of a single LPC (D = 260 nm) displayed green, yellow, red, and orange emission colors at different viewing angles (0°-60°). The modulation effect of PCs provides the same AIE molecule with tunable luminescence. Besides the tunable emission colors, the LPCs also show bright angle-dependent structural colors under natural light. The tunable emission and reflected structural colors provide LPCs with great potential in the fields of display, information encryption, and anti-counterfeiting.