Multicolored Dual‐Band Zinc Anode‐Based Electrochromic Device with Four‐Mode Conversion Based on Phytic Acid‐Doped Polyaniline

Abstract Dual‐band electrochromic devices (DECDs) can regulate the transmittance of visible (VIS) and near‐infrared (NIR) light, representing a significant advancement for smart windows. However, current DECDs are limited by a dearth of color options and the inherent challenges in achieving independent control over VIS and NIR transmission. Herein, this study develops a multi‐color, multi‐mode dual‐band zinc anode electrochromic device (ZECD) using phytic acid‐doped polyaniline (PANI). Due to PANI's unique redox properties, this device produces colors of bright yellow, yellow, blue, and purple, enhancing visual appeal. More importantly, by leveraging the nonlinear relationship between polariton/bipolaron concentration in PANI and applied potential, the device can operate in bright, cool, dark, and warm modes, allowing independent control of VIS and NIR lights. Additionally, introducing phytic acid effectively reduces PANI's bandgap, optimizes its molecular electrostatic potential distribution, and significantly improves the redox reaction reversibility. Therefore, the ZECD shows high transmittance modulating ability (49.9% at 530 nm, 22.1% at 1000 nm), fast response times (61.4 and 19.2 s at 530 nm, 51.6 and 26.0 s at 1000 nm for bleaching and coloring, respectively) and excellent cycling durability (10 000 cycles with 63.2% retention at 530 nm, 70.9% retention at 1000 nm).