High-temperature infrared modulation using multilayer graphene enabled by ionic liquid gel electrolyte

Abstract Dynamic modulation of infrared (IR) radiation is vital for advanced thermal management applications such as radiative cooling and infrared stealth. Multilayer graphene (MLG) is a promising candidate for such modulators due to its tunable IR emissivity. However, existing MLG-based devices fail to maintain stable operation at elevated temperatures. This study presents a novel MLG-based IR modulator incorporating a thermally robust ionic liquid gel polymer electrolyte composed of PVDF-HFP and [HMIM]NTf2. The device demonstrates stable performance up to 403 K. Structural and performance evolution with temperature was investigated via scanning electron microscopy, Raman spectroscopy, x-ray diffraction, and electrochemical methods. Elevated temperatures enhance ion mobility and dynamic response but also accelerate intercalation-induced structural degradation in MLG, thereby reducing device lifetime. This work provides a comprehensive understanding of the thermal behavior of MLG-based IR modulators and proposes a viable strategy for their high-temperature operation.