Operando Colorations from Real-Time Growth of 3D-Printed Nanoarchitectures.

Artificial 3D nanostructures can produce precise and flexible coloration. However, their real-time color changes during 3D nanoprinting remain unexplored due to the inherent challenges of in situ transient measurements and observations. In this study, we developed and evaluated a 3D-printing system which supports the operando observation/measurement of the color dynamics of subwavelength metallic nanoarchitectures fabricated in real time. During 3D printing, the dimensions and geometries of the 3D nanostructures grow over time, producing a large library of optical spectra associated with real-time color changes. Only a timer is required to define the expected colors from a single 3D print run, which expands the utility of the CIE 1931 diagram. Fin-like nanostructures are used to toggle colors based on the polarization effect, as well as produce color gradients. Based on structural coloration, we designed and printed nanoarchitectures to animate desired color patterns. Moreover, the resulting color dynamics can also serve as an operando identifier for real-time structural information during 3D nanoprinting. A single print run enables a comprehensive library of desired colorations to be created efficiently, due to the flexibility in time-dependent controllability and 3D geometries at the subwavelength scale. Therefore, 3D nanoprinted plasmonic structures displaying time-varying colorations (4D printing of colors) have a strong potential for application in digital displays, molecular sensors, data storage, and optical security. This article is protected by copyright. All rights reserved.