Self-adaptive IR emitter with a solution-processed VO2 active layer for tunable radiative cooling

Controlling the infrared (IR) emissivity of a photonic structure as a function of temperature is essential for regulating thermal emission. However, such self-adaptive radiative control often requires sophisticated fabrication processes to achieve the desired emissivity modulation, making large-scale implementation challenging. Here, we demonstrated a simple 1D photonic structure consisting of spin-coated VO2/ZnS/Al that does not require a costly vacuum deposition and/or lithography process for forming the active layer. Based on the phase change in VO2, over 50% modulation depth of peak emissivity was achieved in the atmospheric window. We also unraveled the optical constants of the solution-processed VO2 films using IR ellipsometry under temperature control, enabling realistic prediction of the emissive performance.