Researchers at Koç University have demonstrated that modifying both the internal crystal lattice and the surface of cesium lead iodide (CsPbI₃) quantum dots substantially improves their ability to emit light at elevated temperatures.
Untreated CsPbI₃ quantum dots begin to lose structural integrity and photoluminescence around 60 °C, as heat softens the lattice, strips away surface ligands, and creates defects that divert energy into nonradiative recombination.
The team synthesized quantum dots in which a small fraction of lead atoms were replaced with either cobalt or silver, and then passivated the surfaces with a mixture of chloride and iodide ions.
X-ray diffraction, transmission electron microscopy, and a suite of optical spectroscopy techniques tracked the materials from 20 °C to 80 °C.
Both doped variants retained their cubic morphology, showed less particle aggregation, and maintained stronger, better-defined light emission up to 80 °C, expanding the thermal stability window by roughly 20 °C.
Time-resolved photoluminescence measurements revealed that the rise in thermally activated nonradiative recombination rates was reduced by more than 60 percent compared with untreated dots.
Silver-doped dots exhibited the greatest structural stability, with lattice expansion of only about 0.6 percent during heating versus roughly 1.5 percent for untreated and cobalt-doped samples, and the smallest heat-induced narrowing of the electronic bandgap.
The study, published open-access in Nanoscale, was conducted at the material level; further work is needed to confirm whether the improved stability translates into longer operational lifetimes in complete devices such as LEDs or solar cells under real-world cycling conditions.
Quantum dots keep their glow under heat after dual modification
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