All-solid-state-infrared-IR-adaptive-electrochromic-devices-ECDs-with-a-wide-color-gamut-distribution-have-long-been-sought-after-for-multiple-applications-Although-the-signal--is-camouflaged-in-the-IR-band-through-ECDs-the-target-can-still-be-detect

All-solid-state infrared (IR) adaptive electrochromic devices (ECDs) with a wide color gamut distribution have been in high demand for various applications. However, conventional ECDs face limitations as their signal is hidden in the IR band, which hinders detection in other bands. Moreover, the transmittance in the visible band changes when conventional ECDs alter their IR radiation characteristics, further restricting their application. Therefore, the development of dual-band modulation technologies across the entire visible and IR region has been a major challenge.

In this study, we demonstrate the use of the Ge/HfO2 F-P cavities structure to create ECDs with various rich structure colors and IR adaptive modulation. Based on the optical interference principle, the thickness of HfO2 is adjusted to achieve distinct nanocavity resonances in the reflection spectra. Since Ge and HfO2 are IR transparent materials, this structure can produce visible multicolor and IR dynamic emittance modulation for all-solid-state ECDs with F-P cavity structure. This marks the first time an all-solid-state ECD with visible multicolor and IR adaptive modulation has been demonstrated.

Furthermore, the Ge/HfO2 F-P cavities structure can be applied not only to all-solid-state ECDs but also to flexible polyaniline devices, achieving emissivity modulation in the spectral range of 2.5-25 ﾵm with a maximum range of about 0.28 and 0.27, respectively. This new strategy provides an excellent opportunity for multispectral applications.