Improved electrochromic performance of polyaniline film based on well-ordered 3D micro array

Polyaniline (PANI) with a well-ordered 3D micro array is prepared by using MEMS processes and its electrochromic properties are investigated by comparison with a 2D planar one. The 3D sample has similar response speeds to the 2D one but displays (~1.2×) higher specific capacitance than the latter due to its more PANI content under the same footprint. The 3D micro array is also helpful to enhance the mechanical strength of the PANI film against repeated electrochemical cycling. Moreover, because the 3D array is well-ordered and also its feature size (~4 μm) is comparable to the infrared wavelength, strong interaction occurs between the infrared light and the structure; consequently, the 3D sample shows much larger emissivity modulation (~0.3) than the 2D one (~0.1).