This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Quantum dots are semiconductor crystals only a few nanometers in size. Their ability to produce bright, precisely tunable colors has made them promising materials for light-emitting diodes, displays, solar cells and other optoelectronic technologies.
Yet heat remains a major obstacle to their practical use. A study from Koç University demonstrates that modifying both the internal crystal lattice and the surface of perovskite quantum dots can substantially improve their thermal stability. While untreated quantum dots began to lose their structural integrity and light emission at around 60°C (140°F), the modified materials remained brightly emissive and retained their cubic structure at temperatures of up to 80°C (176°F).
The open-access study, published in Nanoscale, was conducted by Pouriya Naziri, Saba Sepahban Shahgoli, Hadi Jahangiri and Professor Umut Aydemir of Koç University. The researchers focused on cesium lead iodide, or CsPbI₃, quantum dots. These nanocrystals possess attractive optical and electronic properties, particularly for red and near-infrared applications.
However, their crystal structure is inherently unstable and can deteriorate when exposed to heat, light or environmental conditions. As their structure changes, defects can form within the material and on its surface. These defects create pathways through which absorbed energy is lost as heat instead of being released as light—a process known as nonradiative recombination.
Surface molecules that help stabilize the nanocrystals can also detach at elevated temperatures, accelerating degradation. To address these interconnected problems, the Koç University team combined two strategies: replacing a small proportion of the lead atoms in the crystal lattice with cobalt or silver and passivating the quantum dots' surfaces with a mixture of chloride and iodide ions. The researchers synthesized pristine CsPbI₃ quantum dots alongside cobalt- and silver-doped versions.
They then examined how the materials responded to temperatures ranging from 20°C to 80°C (68°F to 176°F). A range of structural and optical techniques—including X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy, time-resolved photoluminescence, ultraviolet-visible absorption spectroscopy and Fourier-transform infrared spectroscopy—was used to track changes in the samples. The untreated CsPbI₃ quantum dots showed signs of lattice distortion and pronounced emission quenching above approximately 60°C (140°F).
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