Jeonbuk National University (JBNU) Professor Kwangwoon Jeong's research team (College of Engineering, Department of Polymer -Nano Science &Technology · Graduate School, Department of Nano Convergence Engineering) has newly synthesized a pi (π)-expanded viologen-based electrochromic material and developed a next-generation smart window material using it.

The research, which has attracted attention in the field of energy-saving optical technologies, was selected as a cover article in the internationally prestigious materials chemistry journal Advanced Materials (IF 26.8, top 2.3%) on October 9, 2025.

Electrochromic materials are functional substances that induce oxidation–reduction reactions in response to an externally applied voltage, enabling control of color and transmittance. They can be applied in various fields that require energy efficiency, such as buildings and automobiles, electronic displays, and security optical devices.

Led by Pham Hu Huan, a doctoral candidate, the study's core achievement was the implementation of a novel electrochromic material capable of precisely controlling color and transmittance by voltage application alone.

Conventional electrochromic materials have been limited to simple color changes. In this study, the research team precisely designed the molecular structure of the pi-expanded viologen-based electrochromic material and applied nanoscale alignment control techniques to enable selective transmittance control using the polarization of light. This makes it possible to fabricate high-function smart windows that switch between transparent, translucent, and colored states according to user requirements.

Through experiments, the team confirmed that the developed material demonstrated commercialization-level practicality and durability, including low operating voltage below 5 V, implementation of three selectable colors, and enhanced thermal, mechanical, and chemical stability achieved through photopolymerization-based manufacturing.

Pham Hu Huan, the doctoral candidate who led the research, said, “Viologen-based electrochromic smart windows can be driven with minimal energy within 5 V, and their thermal, mechanical, and chemical stability is greatly improved through photopolymerization. This study overcomes the limitations of existing electrochromic materials and demonstrates the potential to evolve into a core technology for energy-saving optical systems. Through future commercialization research, practical applications in architecture and security optics are expected.”

Meanwhile, this research was conducted with support from the National Research Foundation of Korea's Research Center Support Program, Mid-Career Researcher Support Program, and Future Materials Discovery Program, and from the Ministry of Education's 4th-phase BK21 (Brain Korea 21) project.