Coordination polymer crystals show promise as new generation of light sources for industry, medicine

New forms of light-emitting materials called phosphors, with better efficiency than current options, are being developed by researchers at the National Institute for Materials Science (NIMS) in Japan, along with colleagues at Tokyo University of Science and Hokkaido University. . It’s their job. published In the journal Advanced Materials Science and Technology.

Phosphors absorb electromagnetic radiation energy, including Visible light and X-rays, and then emit it in colors depending on their properties. They are used in many applications, including Light emitting diodes (LEDs), display screens, scintillators that detect radiation such as X-rays, and optoelectronic devices.

“We need to find phosphors that can be used with easily tuned emission so that they can be exploited in an ever-expanding field of applications,” says Takayuki Nakanishi of the NIMS team. “In this work we have developed a new type of polymer crystal with very narrow linewidth emission bands suitable for making the next generation of microLEDs.” These special LEDs are expected to be used in many emerging applications. Industrial applications.

The work is based on luminescent lanthanide polymer crystals made of components that contain a central europium atom (lanthanide element) complexed with surrounding organic chemical groups. Crystal formation and aggregation can be controlled to tailor the optical properties of the product to the intended application. Polymer nanospheres were found to exhibit the highest optical performance.

“The most innovative aspect of our research is that it shows that polymer crystals with so-called coordination bonds can be used as a wide range of active and thermally stable phosphors from nano- to macro-size. ” says Nakanishi.

The next challenge for the team is to expand the range of wavelengths that can be used to excite the material. Existing phosphors are activated by ultraviolet radiation. But to extend their utility to many more applications, the team hopes to move to other wavelengths, particularly longer and therefore lower-energy wavelengths.

In addition to high light emission efficiency and their advantages Thermal stability, the new phosphors are also very easy to crystallize and readily disperse in solvents. These latter two properties make them well suited for the mass manufacturing that will be required to fully realize their potential.

“We expect the nanoscale. Polymer Spheres using coordination polymers like ours will become a new and versatile fluorescent material on par with the currently better-known quantum dots,” concludes Nakanishi.