By overcoming some highly technical and longstanding roadblocks, a team of scientists has managed to produce what are described as the brightest fluorescent materials in existence. The researchers have succeeded in transferring the properties of highly fluorescent dyes to solid optical materials, opening up new possibilities in everything from the development of next-generation solar cells to advanced lasers.
The research was carried out by scientists at Indiana University and the University of Copenhagen, who set out to solve a 150-year-old problem involving fluorescent dyes. The problem is known as “quenching” and occurs when dyes are converted to solid states, which causes them to bunch up tightly and become electronically coupled, dulling their fluorescent glow. This issue of quenching plagues the great majority of the more than 100,000 dyes that exist today.
"The problem of quenching and inter-dye coupling emerges when the dyes stand shoulder-to-shoulder inside solids," says study author Amar Flood, a chemist at Indiana University. "They cannot help but 'touch' each other. Like young children sitting at story time, they interfere with each other and stop behaving as individuals."
Flood and his colleagues believe they have found a solution to this problem, through the use of star-shaped macrocycle molecule that stops the fluorescent molecules from interacting with one another.
These so-called cynostars were mixed with the colored dyes in a colorless solution, which enables the dyes to maintain their optical properties as the mixture forms into what are called small-molecule ionic isolation lattices (SMILES). In turn, these lattices can be grown into crystals, turned into dry powders, spun onto thin films and even directly integrated into polymers.
This is an approach that has been investigated before, though with one key difference. Earlier attempts had sought to create space between the dyes through colored macrocycle molecules, but the team found that by using colorless versions instead, the fluorescent dyes were left with the space they need to do their thing.
"Some people think that colorless macrocycles are unattractive, but they allowed the isolation lattice to fully express the bright fluorescence of the dyes unencumbered by the colors of the macrocycles," says Flood.
The team sees many possibilities for these new ultra-bright materials, noting solar energy harvesting, bioimaging, display technologies, light-switchable materials and lasers as just a few of the potential applications. For now, however, the researchers plan to continue studying the properties of the structure to lay the groundwork for these kinds of practical uses down the track.
"These materials are totally new, so we do not know which of their innate properties are actually going to offer superior functionality," says Flood. "We also do not know the materials' limits. So, we will develop a fundamental understanding of how they work, providing a robust set of design rules for making new properties. This is critical for putting these materials into the hands of others – we want to pursue crowd sourcing and to work with others in this effort."
The research was published in the journal Chem.
Source: Cell Press via EurekAlert