Liu Yang, Zhang Yong
Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117583.
NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456.
ACS Nano. 2021 Apr 27;15(4):7628-7637. doi: 10.1021/acsnano.1c01180. Epub 2021 Mar 19.
Naked-eye-visible color/graphical patterns have shown significant potential in optical encryption. However, current strategies for optical encryption are usually based on static or homogeneous information, which limits their applications in multivalue coding and advanced confidential encryption. Here, we propose a concept of spatiotemporally tunable optical encryption by constructing a multilevel binary-color spatial heterojunction pattern into the time dimension. This multiple coding strategy can enable a simple pattern much more difficult to be counterfeited and keep the facile authentication by naked eyes or smartphone at the same time. As a proof of concept, we fabricated a moving red-green heterojunction pattern by elaborately utilizing the directional swelling process of a poly(dimethylsiloxane) matrix in organic solvents and the ion-exchange property of a perovskite quantum dot wrapped in it. We demonstrate that trioctylphosphine plays a significant role in endowing the red-green heterojunction with a stable and distinct interface for better perception by eyes. The directional swelling and following ion-exchange dynamics in the local interface indicate that we can tailor the movement of the binary-color heterojunction in a quasi-continuous way orthogonal variables of swelling ratio and ion concentration gradient. The concept of heterojunction-based multivalue optical encryption in the time dimension is independent with other dimensions, indicating a promising compatibility with the existing optical encryption systems.
肉眼可见的颜色/图形模式在光学加密中显示出巨大潜力。然而，当前的光学加密策略通常基于静态或均匀信息，这限制了它们在多值编码和高级保密加密中的应用。在此，我们提出了一种时空可调谐光学加密的概念，即将多级二值彩色空间异质结图案构建到时间维度中。这种多重编码策略能够使一个简单的图案更难被伪造，同时保持通过肉眼或智能手机进行便捷认证的能力。作为概念验证，我们通过精心利用聚二甲基硅氧烷基质在有机溶剂中的定向溶胀过程以及包裹在其中的钙钛矿量子点的离子交换特性，制备了一种移动的红绿异质结图案。我们证明三辛基膦在赋予红绿异质结稳定且清晰的界面以便于眼睛更好地感知方面起着重要作用。局部界面中的定向溶胀和随后的离子交换动力学表明，我们可以通过溶胀率和离子浓度梯度的正交变量以准连续的方式调整二值彩色异质结的移动。基于异质结的时间维度多值光学加密概念与其他维度无关，这表明它与现有光学加密系统具有良好的兼容性。
