Phys.org July 9, 2024
Colloidal semiconductor nanocrystals based on CdSe have been precisely optimized for photonic applications in the visible spectrum. A team of researchers in the US (University of Illinois Urbana-Champaign, Carle Illinois College of Medicine, Urbana) developed homogeneous nanocrystals with tunable bandgaps in the infrared spectrum based on HgSe and HgxCd1−xSe alloys derived from CdSe precursors. They found that Ag+ catalyses cation interdiffusion reduced the CdSe–HgSe alloying temperature from 250 °C to 80 °C. Together with ligands that modulated surface cation exchange rates, interdiffusion-enhanced Hg2+ exchange of diverse CdSe nanocrystals proceeded homogeneously and completely. The products retained the size, shape and uniformity of the parent nanocrystals but exhibited enhanced absorption. After passivation with heteroepitaxial CdZnS shells, photoluminescence wavelengths were tunable in the shortwave infrared by composition without changing size, with 80–91% quantum yield and linewidths near 100 meV. According to the researchers these materials may find applications in infrared photonic devices and infrared bioimaging… read more. TECHNICAL ARTICLE
Dependence of photophysical properties on Hg2+… Credit: Nature Synthesis, 03 July 2024