Polarization‐Dependent and Color‐Tunable Electrochromic Smart Windows: Uniaxially Oriented and Polymer‐Stabilized Viologen‐Based Liquid Crystal Networks

Viologen‐based reactive mesogen (VRM) is newly designed and synthesized for the development of polarization‐dependent, color‐tunable, and transparent electrochromic (EC) smart windows. By controlling electric field, the color of VRM can be intentionally tuned due to the formation of dication (D state), cation‐radical (C state), and neutral state (N state). Based on the deep understanding of phase transition of VRM, a uniaxially oriented VRM hierarchical nanostructure is successfully constructed on the macroscopic area by simple coating and self‐assembly processes. The subsequent photopolymerization significantly improves thermal, mechanical, and chemical stabilities of the VRM thin film. In addition to the control of color, the transmittance of uniaxially oriented VRM‐based EC smart window can be precisely tuned by rotating a linear polarizer. The newly synthesized viologen‐based reactive mesogen (VRM) is used for the fabrication of polarization‐dependent, color‐tunable, and transparent electrochromic (EC) smart window. The VRM EC smart window has potential for advancing privacy and information security technology.