In situ growth of Prussian blue nanoarrays for electrochromic material with ultra-high optical modulation

Abstract

Low-dimensional nanostructures have been widely recognized for accelerated electrochromic redox kinetics. Prussian blue (PB), a typical electrochromic material, exhibits remarkable electrochemical activity. However, existing template-based methods for fabricating PB nanoarrays is often complex and displays unsatisfactory optical modulation. In this study, we successfully achieved in situ growth of PB nanorod arrays on ITO substrates through a straightforward template-free approach. The resulting PB nanorod arrays feature sufficient inter-rod voids, which shorten the ion/charge transport rout and enable full utilization of active sites at the film base, resulting in exceptional electrochromic performance. The optimized PB nanoarrays demonstrates unprecedented optical modulation (ΔT = 87.45 %), fast switching speeds (t_b/t_c = 3.7/4.0 s), high coloration efficiency (CE = 138.8 cm²·C⁻¹), excellent cycling stability (80 % capacity retention after 2000 cycles) and outstanding multicolor electrochromic performance. Moreover, the electrochromic device based on this film also exhibits excellent electrochromic performance with an ultra-high optical modulation (ΔT = 83.9 %). This work presents a promising and feasible approach for producing high-performance electrochromic materials with exceptional optical modulation, suitable for a wide range of practical applications.