Researchers have successfully created metal-organic framework thin films on a substrate while precisely controlling the direction in which the crystals grow, ensuring they are organized and without any gaps. These exceptional thin films are anticipated to be beneficial for applications such as optical sensors, optical components, and transparent sheets for gas adsorption.
While table salt and refined sugar appear white to us, this is due to their colorless crystals scattering visible light. However, this characteristic of crystals can be less than ideal for materials used in optical and electrical devices.
Metal-organic frameworks are a prime example of such materials. These crystalline structures with micropores have gained attention for their potential as next-generation materials that could also address environmental challenges like hydrogen storage and carbon dioxide capture. A team from the Graduate School of Engineering at Osaka Metropolitan University discovered a method to manage the crystal growth in thin films, which drastically reduces light scattering.
Led by Associate Professor Kenji Okada and Professor Masahide Takahashi, the team developed a technique to produce thin films on substrates by guiding the crystals to grow in an orderly fashion with the help of a modulator. This modulator was comprised of a diluted solution of acetic acid, the primary component of vinegar, combined with sodium acetate, which interacted with a copper-based medium to promote growth in a single direction.
By ensuring the crystals are neatly arranged without any gaps, the researchers successfully created a thin film of exceptional quality.
“The thin films produced in this research feature numerous pores at a molecular scale, which allows light to pass through them effectively,” explained Professor Okada. “These films are anticipated to be employed as optical sensors, optical components, and transparent gas adsorption sheets that leverage changes in optical properties during the adsorption of molecules.”
