Free-standing iridescent films: Crafting circularly polarized luminescence from blue to NIR-II for enhanced anti-counterfeiting performance

Abstract

Circularly polarized luminescence (CPL) has recently garnered significant attention due to its promising applications. Current research efforts are predominantly concentrated on enhancing CPL emission with a specific focus on increasing both emission efficiency and luminescence dissymmetry factor (glum). Moreover, how to achieve large-scale fabrication of chiroptical materials with excellent CPL performance still remains a challenge. In this work, we present a kind of photonic crystal films, possess excellent CPL performance with a high glum as well as large luminescent quantum yield when loaded with various luminescent inorganic nanomaterials. Based on this feature, for the first time, we have achieved a distinctive CPL emission with broad spectrum spanning from blue to second near-infrared (NIR-II). Moreover, through applying different fabrication technologies, the distribution of emitters in the CPC samples can be regulated, which holds the key for the CPL performance. Building upon this foundation, we present two illustrative examples of highly efficient chiroptical anti-counterfeiting techniques employing screen-printing technology and arbitrary cutting treatments. This work not only offers a versatile approach for crafting high-performance CPL-active materials but also underscores their potential in the anti-counterfeiting domain and the feasibility of large-scale production.