Towards a large-scale and high-performance smart window based on Prussian blue: a revolutionary two-dimensional-material assisted in situ growth preparation method utilizing MXene†

Abstract

Electrochromic smart windows (ESWs) hold great promise in improving energy efficiency in buildings. However, the production of large-scale ESWs still faces significant challenges due to equipment limitations and associated costs. This paper presents a simple, cost-effective, and environmentally friendly method for preparing Prussian blue (PB) films using a two-dimensional-material assisted in situ growth (TAIG) method. The growth mechanism of PB films prepared through the TAIG method was elucidated using SEM, TEM, and XPS characterization techniques. The PB films fabricated using the TAIG method demonstrate exceptional electrochromic properties, including multi-color modulation capabilities (colorless, blue, green, and yellow), a high optical modulation of 65.89% at 713 nm, fast switching times (5.9 s for coloring and 5.4 s for bleaching), and a high coloring efficiency of 81.73 cm² C⁻¹. Importantly, after 10 000 cycles, there was virtually no degradation of optical modulation of PB films. The electrochromic enhancement mechanism was elaborated in this paper. A comparison between PB films prepared via the TAIG method and the electrodeposition method was conducted using TG and GIWAXS tests. The PB films prepared through the TAIG method exhibit a low structural water content and a polycrystalline structure. DTF theoretical calculations were further carried out to confirm the lower band gap and great electron transition. Additionally, the successful fabrication of large-scale ESWs measuring 100 × 70 cm² using the TAIG method demonstrates its practicality for industrial-scale production. Simulation studies of solar irradiation confirm the shielding capabilities of ESWs and their effectiveness in regulating indoor temperatures. In conclusion, this study represents a significant step towards the performance promotion and industrial-scale production of ESWs, contributing to the development of energy-efficient building solutions.