Multi-pattern polyaniline electrochromic device by controllable three-dimensional movement of ions

Multi-mode and multi-color electrochromic devices (ECDs) have enormous potential for a wide range of applications. However, achieving diverse electrochromic modulation often requires the compounding of different electrochromic materials and the design of complex device structures, which poses a significant challenge. Herein, we propose a novel pre-nucleation electrodeposition method to fabricate polyaniline (PANI) films with high homogeneity and adhesion, and demonstrate a multi-pattern polyaniline electrochromic device by controllable three-dimensional movement of ions for the first time. The resulting PANI films exhibit good cycling stability, retaining approximately 89 % of the active charge after 100 cycles. By combining voltage and current drive modes, the ECDs are able to achieve different optical states in different regions. This dual-mode control strategy results in the highest optical contrast of 44.3 % between different regions of the ECDs, fast switching times (bleaching time and coloring time are 11.06 s and 12.42 s, respectively), and excellent cycle stability (93 % of the maximum transmittance modulation is maintained after 150 cycles). Our discovery provides a new approach to achieve multi-pattern electrochromism using a single electrochromic layer. It has potential applications in multifunctional smart windows and multi-mode color displays.