Thermochromic Ni(II) Organometallics With High Optical Transparency and Low Phase‐Transition Temperature for Energy‐Saving Smart Windows

Abstract

Thermochromic smart windows with rational modulation in indoor temperature and brightness draw considerable interest in reducing building energy consumption, which remains a huge challenge to meet the comfortable responsive temperature and the wide transmittance modulation range from visible to near‐infrared (NIR) light for their practical application. Herein, a novel thermochromic Ni(II) organometallic of [(C2H5)2NH2]2NiCl4 for smart windows is rationally designed and synthesized via an inexpensive mechanochemistry method, which processes a low phase‐transition temperature of 46.3 °C for the reversible color evolution from transparent to blue with a tunable visible transmittance from 90.5% to 72.1%. Furthermore, cesium tungsten bronze (CWO) and antimony tin oxide (ATO) with excellent NIR absorption in 750–1500 and 1500–2600 nm are introduced in the [(C2H5)2NH2]2NiCl4‐based smart windows, realizing a broadband sunlight modulation of a 27% visible light modulation and more than 90% of NIR shielding ability. Impressively, these smart windows demonstrate stable and reversible thermochromic cycles at room temperature. Compared with the conventional windows in the field tests, these smart windows can significantly reduce the indoor temperature by 16.1 °C, which is promising for next‐generation energy‐saving buildings.

Supramolecular Polymer‐Based Ionogels Enable Large‐Scale Fabrication of Stable Smart Windows with Room‐Temperature Closed‐Loop Recyclability and Self‐Healing Capability

“…Due to the rational material design, the T lum and ΔT sol of the ISP/30%IL 0.8 were both higher than those of reported thermochromic smart windows (Figure 3c). [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] T lum , T sol , luminous modulation capability (ΔT lum ), and ΔT sol of the ISP/30%IL 0.8 ionogel were unchanged after 2000 cycles of heating to 40 and cooling to 20 °C (Figure 3d), indicating that the thermochromic capability of the ionogel had good repeatability. Due to the good mechanical strength of the ISP/30%IL 0.8 ionogel and the non-volatility of ILs, the thermochromic performance of the ISP/30%IL 0.8 ionogel was well maintained after 2000 bending cycles and 4 months of storage at −30, 50 °C, 90% RH, and vacuum (relative vacuum pressure = −0.098 MPa) (Figure 3d).…”

Thermochromic Hydrogels with Adjustable Transition Behavior for Smart Windows

“…Windows are considered to be one of the least energy-efficient parts of buildings. − Ordinary transparent glass cannot effectively limit solar radiation from entering or exiting buildings due to its high heat transfer coefficient. The seasonal nature of the availability of light makes the average daily light energy several times higher in summer than in winter months.…”

Multifunctional thermochromic smart windows for building energy saving

“…Smart windows have been developed to intelligently regulate indoor solar radiation in response to external stimuli and consequently reduce heat exchange to conserve energy, 5,6 including electrochromic, 7 mechanochromic, 8 magnetochromic, 9 photochromic, 10,11 and thermochromic smart windows. 12,13 The former three types are known as active smart windows that need extra energy input to trigger and maintain the “ON” or “OFF” state.…”