Graphene-Based Tunable Coloration Film through Intercalation

Abstract

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.

Full-colour switching in graphene-based Fabry-Perot nanocavities actuated by intercalation

“…2d, with the thickness of MLG around 100 nm and the thickness of SiO 2 ranging from 50 nm to 250 nm. Pristine MLG display a gray colour, which turns to bright yellow after Li intercalation, consistent with previous researches 14,17 . The colours of MLG-based F-P nanocavity devices are quite monotonous before intercalation, as seen in Fig.…”

“…Regarding MLG-based F-P nanocavities, the colouration mechanism is induced by an interference effect, which is different from the band structures-based colouration mechanism in conventional graphenebased EC devices 14,17,24 . The interference effect for MLG-based F-P nanocavity could be adjusted by the degree of lithiation of MLG, allowing for tunable colour chromaticity.…”

“…Simulation results (see Figure S9) show that MLG with different thickness on Ni foil only exhibit inconspicuous structural colours before and after Li intercalation. The LiC 6 lms on Ni foil with different thickness display orange-yellow relevant colours, which can be easily mistaken for the gold colour of fully lithiated MLG (LiC 6 ) 14,17 . Figure 1g illustrates the re ectance of MLG on Ni foil with the thickness of around 100 nm before and after Li intercalation, for the wavelength ranging from 400 nm to 700 nm.…”

“…Graphite/graphene intercalation compounds (GIC) can address these challenges by offering wide-range reversible tunability of optical properties [13][14][15][16][17] , non-volatile tunability (bistability) [13][14][15][16][17] , high conductivity 17,18 and high energy e ciency 19 . Previous researches have shown that lithium (Li) intercalation can reversibly tune the optical re ectivity 14,16,17 , non-linear optical properties 15 and optical second-harmonic generation (SHG) 13 of multilayer graphene (MLG). This indicates that the optical constant (n, k) of MLG could be tuned by Li intercalation.…”

“…This indicates that the optical constant (n, k) of MLG could be tuned by Li intercalation. Using only MLG, the colour could be tuned from gray to dark blue, dark red, and bright yellow by Li intercalation 14 . This colour gamut are expected to be extended by involving subwavelength structures, as have been demonstrated in other EC devices 10,[20][21][22] .…”