According to a report published on the 15th in Science, an international research team, including members from North Carolina State University and POSTECH in South Korea, has demonstrated a groundbreaking technique for printing metal oxide thin films at room temperature. This innovation has led to the creation of durable, high-temperature-resistant, and transparent flexible circuits.
The researchers developed a method to print metal oxides onto polymers, resulting in flexible and resilient circuits. Traditional metal oxide fabrication requires specialized equipment, which is both slow and costly, and operates at high temperatures. The team aimed to create a technology that could deposit metal oxide films at room temperature.
The new approach involves separating metal oxides from a liquid metal's meniscus. The meniscus is the curved surface of a liquid in a tube, which forms due to surface tension preventing the liquid from overflowing completely. For liquid metals, a thin layer of metal oxide forms where liquid metal meets the air.
By filling a space between two glass plates with liquid metal, a portion of the meniscus extends to the edges of the plates. When the meniscus moves across the surface, the metal oxide adheres to it, creating a thin film. As the exposed liquid metal continually forms new oxide, this results in a continuous "printing" process.
Using this technique, the researchers successfully printed two layers of metal oxide films, each approximately 4 nanometers thick. The resulting films are transparent yet exhibit high metallic conductivity. Moreover, these films maintain their conductive properties at high temperatures, with 4-nanometer films stable up to nearly 600°C and 12-nanometer films stable up to 800°C.
The researchers also demonstrated the practicality of technology by printing metal oxides onto polymers to create soft, flexible circuits. These circuits are robust enough to withstand 40,000 folds while retaining their integrity, showcasing the potential of this new printing technology.
