Stretchable, self-adhesive, multicolored, electrochromic devices based on crosslinked polybutyl acrylate gels for wearable display applications

Abstract

Stretchable electrochromic devices (ECDs) adaptable to complex curved surfaces offer promising applications in wearable displays and intelligent electronic devices for encryption and camouflage. However, conventional polymer gel electrolytes used for all-in-one ECDs are unsuitable for stretchable ECDs owing to their poor stretchability and lack of adhesiveness to the electrode surface. Here, we report a stretchable, self-adhesive, multicolored ECD based on crosslinked polybutyl acrylate (PBA) gel incorporating various electrochromic viologens. The optimized PBA-based EC gel exhibits outstanding mechanical properties (220% stretchability, >27 kPa adhesion strength) and superior ionic conductivity (1.28 mS cm⁻¹). The flexible ECDs demonstrate excellent electrochromic performance with significant transmittance changes (ΔT_max = 82.19%), good response times (t_c,90% = 36 s, t_b,90% = 38 s), and high coloration efficiency (118.1 cm² C⁻¹) at low operating voltages (−0.9 V). By incorporating different viologens, we achieve magenta, blue, and green colors in a single device with stable operation under mechanical deformation. The integration with stretchable silver nanowire electrodes enables fully stretchable devices maintaining stable performance under 30% strain. Furthermore, we demonstrate a proof-of-concept wearable encryption display utilizing the multi-color capabilities. This work presents a significant advancement in stretchable/flexible electrochromic technology, offering potential applications in next-generation wearable displays.