The toxic and expensive phosphors used widely in fluorescent lighting could be eliminated thanks to new research led by a materials scientist at Queen Mary University of London (QMUL).

An international group of scientists led by Dr. Oliver Fenwick, of QMUL’s School of Engineering and Materials Science, modified a mineral called zeolite, commonly found in washing powder, to incorporate tiny clusters of silver atoms. At a very small scale—less than 10 atoms—the silver clusters can emit light.

Small clusters of silver atoms (green spheres) trapped in zeolite cages. Image credit: Dr. Oliver Fenwick.Zeolites are porous minerals that can be found naturally or produced synthetically on an industrial scale. They are rigid and have a well-defined framework made of molecular-scale channels and cavities.

The researchers, from Université de Strasbourg in France, where Fenwick was based when carrying out the research, and KU Leuven, in Belgium, manipulated the characteristics of the zeolite pores to fine-tune the properties of the clusters of silver. Via tailoring of the zeolite host, they demonstrated luminescence efficiencies close to 100%.

“We’ve shown that silver atoms can be assembled in the porous framework of minerals known as zeolites with a level of control not reported previously," says Fenwick. "This has allowed us to tailor very precisely the properties of the silver clusters to meet our needs—in this case an efficient phosphor."

According to Fenwick, the high efficiency of the materials, along with cheap, scalable synthesis, makes them very attractive as next-generation emitters for fluorescent lamps and LEDs—as well as for biological imaging such as for highlighting tumors or cell division.