Toward Next‐Generation Smart Windows: An In‐depth Analysis of Dual‐Band Electrochromic Materials and Devices

Abstract

As the proportion of buildings energy consumption increases, the issue of low energy utilization efficiency becomes increasingly prominent. Approximately 45% of the energy is lost through doors and windows, a significant concern that has drawn society's attention to the potential of electrochromic technology, which can regulate light transmittance and absorption effectively. Specifically, dual‐band electrochromic materials offer a promising solution to this issue, as they can manipulate the transmission ratios of visible (VIS) and near‐infrared (NIR) light to obtain “bright,” “cold,” “warm,” and “dark” independent modes. However, research on dual‐band electrochromic materials and smart windows is still infant, and many challenges including performance and assembly issues, are significant obstacles to the advancement and application of this technology. This review clarifies the basic characteristics of dual‐band electrochromic materials and smart windows, including configurations, operational mechanisms, and performance assessment parameters. In‐depth examination of potential dual‐band electrochromic materials and methods for achieving independent modulation is provided, along with an analysis of the challenges and potential solutions for performance and assembly issues. Finally, the future prospects of dual‐band electrochromic smart windows (ESWs) are underscored. The hope is to eventually facilitate the commercial application of these windows, which can significantly contribute to the creation of modern, energy‐efficient buildings.

“Dark-to-Warm” Smart Windows Enabled by Black-to-Black Electrochromic Copolymers with Minimal Visible and Remarkable NIR Modulation

“…Current DEMs research predominantly focuses on the inorganic materials, small organic molecules, and organic framework materials. 22 Gao and colleagues reported dual-band electrochromic polymers (DECPs) based on polyaniline (PANI). The resulting electrochromic device exhibits a "Bright-to-Cool-to-Dark" transition with moderate visible and NIR modulation, displaying dark blue color, not black, in the "Dark" mode.…”

“…Current DEMs typically transition between “Dark”, “Cool”, and “Bright” modes, lacking a “Warm” mode. Their modulation ability below 1350 nm, crucial for the solar radiation energy, requires enhancement . Given the preference for black color in smart windows, the development of novel dual-band ECPs and corresponding devices capable of transitioning specifically from “Warm” mode to other modes with high optical modulation ability is intriguing.…”

“…Their modulation ability below 1350 nm, crucial for the solar radiation energy, requires enhancement. 22 Given the prefer- ence for black color in smart windows, the development of novel dual-band ECPs and corresponding devices capable of transitioning specifically from "Warm" mode to other modes with high optical modulation ability is intriguing. Since J.R. Reynolds and colleagues introduced the first black-to-transmissive polymers in 2008, 25 subsequent black polymers have been synthesized via Stille coupling or DArP.…”

“…On the other hand, in “Warm” or “Cool” modes, only NIR or visible light is transmitted. Current DEMs research predominantly focuses on the inorganic materials, small organic molecules, and organic framework materials …”