Large area electrochromic displays with ultrafast response speed and high contrast using solution-processable and patternable honeycomb-like polyaniline nanostructures

Electrochromic displays have attained considerable attention attributed to the low energy consumption and open-circuit memory effects. However, the low optical contrast and slow response speed have limited their application fields. To overcome these deficiencies, we focus on the preparation of solution-processable nanostructured electrochromic materials with high contrast and fast response speed. Here, the solution-processable honeycomb-like polyaniline (H-PANI) nanostructure networks were prepared by the combination of chemical oxidative polymerization and template method for the first time. The H-PANI nanostructured film shows improved electrochromic properties owing to large interface area and short diffusion length. And the all-solid-state electrochromic device (ECD-HP) was fabricated by employing spray-coated H-PANI as coloring electrode and spray-coated commercial PEDOT:PSS as counter electrode. The ECD-HP shows high optical contrast (71.6% at 600 nm), ultrafast response speed (447 ms for coloring and 650 ms for bleaching), high coloration efficiency (560.6 cm(2)/C) and remarkable cycling stability (sustaining 96% of its initial optical contrast after cycling 1000 cycles). Furthermore, the large-area patterned electrochromic displays based on H-PANI film were successfully assembled by spray-coating method using masks to form patterns. These demonstrate solution-processable H-PANI could have widely applications in large area patternable electrochromic smart windows and displays.