Researchers at the Electronics and Telecommunications Research Institute (ETRI) developed a transparent film that stably disperses graphene. The film, the transparency of which changes depending on the intensity of light, can be used in a variety of fields, including laser protection devices, smart optical sensors, and AI photonic materials. More broadly, according to the researchers, the development establishes a technology that makes it easier to use graphene materials. Despite its advantageous qualities, namely its excellent strength and electrical conductivity, graphene has been difficult to use in actual industries due to the problem of adhering together. Chemical dispersants are used to solve this problem, but it is difficult to keep the graphene's properties intact. The ETRI researchers developed a photocurable graphene-dispersed colloid and secured the technology to enable graphene to be stably and uniformly dispersed within a polymer and without a dispersant. According to the research, the graphene colloid is stable enough to be stored for long periods of time, more than a year, without graphene precipitation. Transmission electron micrograph showing 5-8 layers of graphene with an area of tens of nanometers spaced at 0.35-nm intervals evenly dispersed within a film-like photocured polymer material. Courtesy of Electronics and Telecommunications Research Institute. The researchers used ultraviolet (UV) light to convert the colloidal layer into a hard film, creating a material that is easy to process while retaining graphene's favorable properties. They said that the technology is environmentally friendly as well; since the graphene-dispersed solution polymerizes to form the film, and the entire graphene colloid is used to form the film, the process does not generate any pollutants. And, because the film manufacturing method uses UV light curing of the graphene colloid, the method supports commercialization, as it can be mass-produced in a continuous process. This contrasts conventional film-making methods that use molds or polymer solutions. The developed graphene-dispersed photocurable transparent film can be applied in various industries such as optics, electronics, and AI by using graphene's unique light-regulating properties, or optical nonlinearity. The film can detect and block strong light and could be used as a laser sensor and protective film to protect a user’s eyes or equipment. It is also expected to be applied to smart optical sensors that can control the intensity of light and detect changes to create more precise advanced sensors, and AI optical materials that use AI to perform computations using light, according to the researchers. The ETRI researchers are working with related companies to consider cooperation regarding commercialization research and mass production systems. The research was published in Applied Science and Manufacturing (www.doi.org/10.1016/j.compositesa.2024.108693).