0315ctt electrochromic glass lo res

[Image above] Grant Stec and Adam Lauchner of Rice University’s Laboratory for Nanophotonics have used an inexpensive hydrocarbon molecule called perylene to create a low-voltage, multicolor, electrochromic glass. Credit: Jeff Fitlow; Rice University

The structures we inhabit—our houses, offices, and buildings—require a lot of energy to keep them at a comfortable temperature. Buildings account for ~39% of energy consumption in the United States, the largest portion of which goes to heating, cooling, and ventilating those buildings.

So efforts to reduce the energy required to heat and cool our structures are a hot topic of research.

And because windows account for a large proportion of the surface of buildings, windows are often targeted for energy efficiency improvements. [As are roofs, but that’s a different story.]

Researchers have already developed a variety of ways to make windows smarter and more energy-efficient, particularly by imparting the ability to control the amount of light and heat they transmit—but a major barrier is high cost. New tunable window technologies need to be inexpensive if they’re going to find a steady foothold in this market.

Rice University researchers have a potential solution with their development of inexpensive electrochromic glass—by sandwiching readily available, color-changing hydrocarbon molecules in between two panes of conductive glass, the researchers have devised a chameleon-like window that offers a wider range of color choices than ever before.

“When we put charges on the molecules or remove charges from them, they go from clear to a vivid color,” Naomi Halas, lead scientist of the new research and director of Rice’s Laboratory for Nanophotonics and its Smalley-Curl Institute, says in a Rice University press release. “We sandwiched these molecules between glass, and we’re able to make something that looks like a window, but the window changes to different types of color depending on how we apply a very low voltage.”

The molecules, a variety of polycyclic aromatic hydrocarbons (PAHs) called perylene, change color in a polarity-dependent manner when voltage is applied. And because PAHs are a byproduct of the petrochemical industry, they’re inexpensive.

So the researchers think their development could have various potential applications, including electrochromic windows that change color to control the amount of light and heat they transmit.

See the glass go chameleon and hear more from the Rice researchers themselves in this short video.

Credit: Rice University; YouTube

The paper, published in ACS Nano, is “Multicolor electrochromic devices based on molecular plasmonics” (DOI: 10.1021/acsnano.7b00364).