No abstract

We have demonstrated that thin films of hierarchical NiO microflakes assembled from nanoleaves can be grown directly on FTO-coated glass substrates using a facile and template-free hydrothermal technique. This hierarchical structure holds the advantages of both nanometre-sized building blocks and microsized assemblies. Thus, the films exhibit highly enhanced electrochromic performances and cyclic stability due to their high surface area and good electrochemical stability. Moreover, a complementary electrochromic device combining the hierarchical NiO microflake film with a self-weaving WO3 nanoflake film is fabricated to further improve the electrochromic performance. As a result, the complementary electrochromic device shows a high optical modulation (73.2% at 550 nm), large coloration efficiency (146.9 cm(2) C(-1) at 550 nm by applying a low coloration voltage of -1.0 V) and fast switching responses with a coloring time of 1.8 s and a bleaching time of 3.2 s. It is also observed that there is no significant degradation of the electrochromic properties after 2000 continuous coloration/bleaching cycles, making it attractive for practical applications.

Inorganic materials have been extensively studied for visible electrochromism in the past few decades. However, the single inorganic electrochromic (EC) material commonly exhibits a single color change, leading to a narrow spectrum of modulation, which offsets or limits the maximally energy-saving ability. Here, we present a wide-spectrum modulated EC device designed by combining the complementary EC nanocomposite of manganese dioxide (MnO 2 ) and Prussian blue (PB) for enhanced energy savings. Porous MnO 2 nanostructures serve as host frameworks for the templated growth of PB, resulting in MnO 2 /PB nanocomposites. The complementary optical modulation ranges of MnO 2 and PB enable a widen-spectrum modulation across the solar region with the development of the MnO 2 /PB nanocomposite. The colored MnO 2 /PB device exhibited an optical modulation of 32.1% in the wide solar spectrum range of 320−1100 nm and blocked 72.0% of the solar irradiance. Furthermore, fast switching responses (2.7 s for coloration and 2.1 s for bleaching) and a high coloration efficiency (83.1 cm 2 •C −1 ) of the MnO 2 /PB EC device are also achieved. The high EC performance of the MnO 2 /PB nanocomposite device provides a new strategy for the design of highperformance energy-saving EC smart windows.

No abstract

No abstract