Integration over Assembly: A Single-Material Approach to Dynamic and Self-Erasing Optical Encryption

Abstract

The evolution of optical encryption demands materials that not only conceal information but also enable sophisticated control over its lifecycle. However, increased functionality requires more complex material compositions or device architectures. To circumvent this trade-off, here we report a conceptual and practical evolution from a dual-material binary architecture relying on external erasure to a single-material ternary system featuring intrinsic self-erasure. In the binary design, pristine (C6H8N3)CdCl3 serves as a nonemissive background, while the two addressable states are provided by its N,N-dimethylformamide (DMF)-activated derivative (i.e., (C6H8N3)CdCl3–DMF, green afterglow) and its Mn2+-doped counterpart (no afterglow). This configuration enables dynamic “1/0” readout and selective information erasure upon exposure to water mist. More critically, the Mn2+-doped compound alone functions as a self-contained, multiresponsive unit, manifesting three addressable states under 254 nm irradiation: an initial red state, an HCl-switched green state, and a solvent-induced “off” state. Exploiting these three discrete states affords compact ternary encryption. Furthermore, the latter two states inherently constitute a built-in self-erasure mechanism, enabling complete pattern disappearance without any external intervention. This progression─from combinatorial assembly to integrated functionality─offers a blueprint for designing streamlined, high-capacity optical security platforms.