by josh perry, editor
researchers from the university of technology sydney (australia) institute for biomedical materials and devices believe that they have found a way around the fundamental physical restraint of thermal quenching, which has dimmed the brightness of ultra-small nanoparticles.
thermal dots could bring advances to led, security inks, and bioimaging.
(uts institute for biomedical materials and devices)
according to a report from uts, this discovery could enhance the resolution and sensitivity of display technologies, security inks, and bioimaging.
the report explained, “to overcome the quenching that dims the brightness of ultra-small nanoparticles, the uts physicists developed a new type of nanoparticle called ‘thermal dots’. by harvesting heat and thermal energy, and converting this energy to more light emissions, the researchers demonstrated a 1000-fold increase in the brightness of the nanoparticles.”
the researchers demonstrated the smallest thermometer, 10 nanometers smaller than the size of a single molecule, which measures the nanoscale changes in temperature using light.
researchers showed that the dark layer on the surface of nanoparticles smaller than 10 nanometers is sensitive to temperature and can be altered to improve the intensity of the nanoparticles.
the research was recently published in nature photonics. the abstract stated:
“thermal quenching, in which light emission experiences a loss with increasing temperature, broadly limits luminescent efficiency at higher temperature in optical materials, such as lighting phosphors and fluorescent probes. thermal quenching is commonly caused by the increased activity of phonons that leverages the non-radiative relaxation pathways.
“here, we report a kind of heat-favourable phonons existing at the surface of lanthanide-doped upconversion nanomaterials to combat thermal quenching. it favours energy transfer from sensitizers to activators to pump up the intermediate excited-state upconversion process.
“we identify that the oxygen moiety chelating yb3+ ions, [yb···o], is the key underpinning this enhancement. we demonstrate an approximately 2,000-fold enhancement in blue emission for 9.7 nm yb3+-tm3+ co-doped nanoparticles at 453 k.
“this strategy not only provides a powerful solution to illuminate the dark layer of ultra-small upconversion nanoparticles, but also suggests a new pathway to build high-efficiency upconversion systems.”