SUMMARY
UCLA researchers in the Department of Material Sciences and Engineering have developed energy-efficient, smart window coatings with wide light bandwidth, high degrees of modularity and high stability towards repeated cycling.
BACKGROUND
Utilizing smart windows’ tunable opacity to control both the timing and amount of light transmission would have a direct reduction in the overall demand for air conditioning and heating. Currently, there are three types of smart windows: photochromic, electrochromic and thermochromic. However, there are inherent disadvantages to this technology, including low transmittance at visible light range for the transparent state, high complexity and cost for fabrication, and short lifetimes. Therefore, a significant need exists for an efficient, stable and long-lifetime window treatment that can be applied inexpensively in order to reduce the global energy consumption.
INNOVATION
UCLA researchers have developed an all-solid thermochromic polymer film for smart window applications. Unlike current thermochromic smart windows, the disclosed film is transparent in colder temperatures, allowing heat to enter, and becomes opaque when warmed, blocking heat. The film can be applied directly to windows or overtop a conducting layer to further enhance uniformity. The modularity of this film is further accentuated by the ability to selectively deposit thicknesses ranging from 2 μm up to several millimeters. The transition temperature of the coating can be controlled based on application needs to be in the range of 25°C-130°C. Importantly, the disclosed film changes its opacity in a broad wavelength range, covering most of the solar flux, and can alternate between opaque and transparent across numerous cycles. Finally, the all-solid nature of the film enhances stability as compared to smart windows which incorporate volatile solvents.
POTENTIAL APPLICATIONS
- Smart windows (commercial buildings, households, automotive)
ADVANTAGES
- Longer life span
- No water containment
- No volatile material containment
- Stable
- Covers broader wavelength range in opacity
- Transition occurs in a narrow temperature range
- Thicknesses from 2 μm up to several millimeters
- No metal/metal oxides or liquid crystals
- Solution processed
STATUS OF DEVELOPMENT
Demonstrated ability to alter light transmission.
RELATED PUBLICATIONS
A Phase‐Changing Polymer Film for Broadband Smart Window Applications