Graphene-Based Tunable Coloration Film through Intercalation

Optical materials with dynamic colors have shown great prospects for applications in display devices, smart windows, and camouflage coatings. Recently, intercalation has been demonstrated to be a powerful strategy for tuning electromagnetic properties of two-dimensional materials ranging from visible to microwave wavelengths, such as the visible color, infrared emission, terahertz radiation, and optical second-harmonic generation. Here, a systematic study of graphene intercalation compound (GIC)-based coloration films is presented. Through lithium (Li), sulfuric acid (H2SO4), and ferric chloride (FeCl3) intercalation, the color of a multilayer graphene (MLG) film transforms from gray to yellow, blue, and dark, respectively. This is attributed to the reconstruction of the band structure of graphene after intercalation, resulting in a significant effect on its optical properties. Furthermore, tunable and reversible color changes of MLG film have been demonstrated by precisely controlling the Li-intercalation process. Our research indicates that intercalation is a versatile strategy for fabricating advanced coloration materials and provides a promising tunable optical surface for the application in sensing, adaptive camouflage, and smart displaying.