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Experiencing the burn of a leather car seat in the heat of the summer or catching a nosy neighbor peering into your kitchen window could soon be things of the past with the new dual-mode liquid crystal smart glass material.

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Yingfei Jiang, a College of Arts and Science graduate student in the Chemical Physics program and the Advanced Materials and Liquid Crystal Institute (AMLCI) at �鶹��ý, and his advisor Deng-Ke Yang, Ph.D., a professor in the Department of Physics, have invented the first ever dual-mode smart glass technology that can control both radiant energy flow (heat) and privacy through a tinted material. They’re currently applying for a patent for this new technology.

According to Jiang, liquid crystal is a unique state of matter. It is an intermediate state with some of the properties of a solid and liquid. It flows like a liquid but has optical properties that can be ordered, like a solid. In other words, you can control how the molecules align, thus you can control how light passes through it. 

Smart glass technology is a material created from electrochromic glass used in windows that can either prevent harsh heat from the sun getting in or tint glass opaque to offer privacy, according to Smart Glass International. This kind of smart glass can be used in buildings, homes and cars for one of those two reasons. 

What makes the dual-mode smart glass different is that it offers both of these benefits. Jiang and Yang created a liquid crystal material that can control both radiant energy flow and privacy.

The window is made up of two pieces of transparent glass and a liquid crystal layer placed in between, creating the smart glass. 

The dual-mode switchable liquid crystal uses both dielectric and flexoelectric properties. The dielectric property is what radiates energy flow that combats hot car seats from the sun’s heat. The flexoelectric property is what creates privacy, which tints windows. 

“This technology was initiated by a discovery by accident,” Jiang said. “We prepared a new liquid crystal mixture and filled the mixture into a liquid crystal cell. When I applied a 50 Hz (Hertz) voltage, an abnormal phenomenon appeared. The cell looks scattered instead of transparent. We explored how to make use of this phenomenon in smart switchable window.”

Without the applied voltage, the window is clear and transparent. Once low frequency voltage is applied to the window, it switches to an optical scattering and absorbing state that creates privacy in the window. 

“We developed another mixture by doping some dichroic dye liquid crystal materials, so that the energy flow could also be controlled,” Jiang said.

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Once a high frequency voltage (1 kHz) voltage is applied to the materials, the window switches to an optical absorbing but non-scattering state, allowing the radiant energy flow to be controlled, essentially blocking the heat.

Combining both of these properties created the dual-mode smart glass that provides both benefits of traditional smart glass in one material. 

“Dual-mode smart window technology could be a trendy and promising component of vehicles and homes in the near future,” Jiang said. “It would completely change the way people interact with inside and outside of vehicles and homes. Both comfort and privacy needs could be satisfied at the same time.”  

To be clear, Jiang didn’t end up at Kent State by accident. 

“The AMLCI at Kent State is one of best liquid crystal specialized programs in the world,” Jiang said. 

To learn more about the Advanced Materials and Liquid Crystal Institute, visit www.kent.edu/amlci.

To read about Jiang’s research, which was published in the journal Physical Review Applied in November 2019, visit .