Flexible and large-area electrochromic infrared devices with superior modulation functionality

Electrochromic devices (ECDs) capable of modulating infrared emission hold great potential in many application fields, including energy harvesting and conservation, sustainable building technology, thermal imaging, and spacecraft thermal control. However, its wider implementation requires the development of innovative strategies to achieve high modulation ratio, high flexibility, low cost, and seamless integration capabilities. Here we present a low-cost, large-area-compatible, solution-process approach for flexible infrared ECDs (IR-ECDs) by designing gradient porous membrane-supported polyaniline (PANI) composite structures. These devices achieve a superior emissivity variation (Δε) of 0.56 across the critical atmospheric transparency window of 8–14, coupled with a large modulation of radiative temperature by 10.9 °C at 40 °C environmental conditions. Remarkably, they retain a high Δε even after 120,000 s of continuous operation, demonstrating exceptional cycling durability with a minimal emissivity decay rate of 0.0145 % per cycle. Furthermore, we demonstrate that the flexible, self-powered IR-ECDs are able to support continuous modulation operation for an impressive duration of circa 20 years for a large device with an area of 1 m 2 , consuming a minimal 1-kilowatt hour (kWh) of electricity. This development paves the way for new, high-efficiency strategies in preparing and deploying high-performance adaptive energy-management applications.