All-solution-processed mid-infrared electrochromics (ASPIRE) for thermoregulation with arbitrary curvatures

Mid-infrared electrochromism provides a powerful approach to dynamically regulate radiative heat transfer, with important implications for building energy efficiency, industrial process optimization, spacecraft thermal control, and personal heat management. However, most reported mid-IR electrochromic devices are fabricated on planar substrates, limiting their adaptability to three-dimensional (3D) or curved surfaces. When applied to such geometries, these devices fail to conform fully, introducing air gaps that increase thermal contact resistance and reduce radiative modulation efficiency. Here, we report an all-solution-processed fabrication methodology that enables electrochromic devices to be directly formed on arbitrarily curved 3D surfaces, effectively transforming the object into an electrically tunable thermal emitter. The device employs poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as both the electrochromic and charge-storage layers, separated by a heterogeneous mixed ionic-electronic conductor composed of HNO₃-doped carbon nanotubes and crosslinked polyacrylamide/lithium chloride hydrogel. This layer-by-layer configuration ensures complete surface conformity and robust electrochemical performance. The resulting mid-IR electrochromic system achieves an emissivity tunability of 0.195 and an apparent temperature modulation of 6.1 °C on planar substrates and 2.3 °C on curved objects. This work establishes a generalizable strategy for outward-facing electrochromic devices, offering broad opportunities for advanced light and heat management technologies.