Coordinating polymer crystals show promise as a new generation of light sources for industry and medicine

Researchers at the National Institute for Materials Science (NIMS) in Japan, along with colleagues at Tokyo University of Science and Hokkaido University, are developing new forms of light-emitting materials called phosphors with improved versatility compared to existing options. their work Published In the journal Advanced materials science and technology.

Phosphors absorb energy from electromagnetic radiation, including visible light and X-rays, and then emit it in colors that depend on their properties. They are used in many applications, including light-emitting diodes (LEDs), display screens, scintillators that detect X-ray-like radiation, and opto-electronic devices.

„In order to use them in an ever-expanding field of applications, we need to find phosphors with easily tuned emissions,” says Takayuki Nakanishi of the NIMS team. „In this work, we have developed a new type of polymer crystals with very narrow linewidth emission bands that are suitable for making next-generation micro-LEDs.” These specialty LEDs are expected to be used in many emerging industrial applications.

Based on fluorescent lanthanide polymer crystals built from elements containing a central europium atom (a lanthanide element) complexed with surrounding organic chemical groups. The formation and aggregation of crystals can tailor the optical properties of the product to the intended application. Nanospheres of polymer were found to provide the highest optical performance.

„The most innovative aspect of our research is that it reveals that polymer crystals with so-called coordination bonds can be used as functional and thermo-stable phosphors in a wide range from the nanoscale to the macroscale,” says Nakanishi.

The next challenge for the team is to extend the range of wavelengths that can be used to excite materials. Current phosphors are excited by UV radiation. But to extend their use to even more applications, the team hopes to move to other wavelengths, particularly longer and lower-powered ones.

In addition to the advantages of high light emission efficiency and thermal stability, the new phosphors are very easy to crystallize and easily dispersible in solvents. These latter two properties make them well suited for large-scale production, which must fully realize their potential.

„We expect that nanoscale polymer spheres using coordination polymers such as ours will become a new and versatile luminescent material parallel to the currently well-known quantum dots,” Naganishi concludes.