Rapid-response electrochromic devices with self-wrinkling polyaniline for enhanced infrared emissivity modulation

Electrochromic devices (ECDs) based on polyaniline (PANI) can alter their optical properties reversely by varying applied voltages, showing great potential in infrared (IR) information concealment. However, the traditional ECD with a flat PANI layer tends to perform unsatisfactorily in IR emissivity regulation and response time, resulting in risks of information leakage and low transfer efficiency. To address these challenges, a wrinkled microstructure is incorporated into the PANI layer (PANI-W) of the ECD (ECD-W) through a self-wrinkling method. Theoretic simulations combined with experimental results verify that the PANI-W endows an enhanced antireflection effect and a more complete redox degree. As a result, the ECD-W exhibits an exceptional IR emissivity modulation (0.375) and a short response time (1.8 s/2.6 s), allowing it to realize a temperature modulation of 8.9 °C. Moreover, various patterned and anti-patterned ECDs-W are feasibly prepared without masks, and more complicated patterns can be realized by erasing the unnecessary part of PANI-W on the ECDs-W. Two encryption/decryption strategies based on these ECDs-W are presented to provide more secure ways for IR information concealment. This research offers guidance to achieve high-performance ECDs with more effective spectrum regulation and faster responses, showing great potential in thermal regulation and IR information protection.