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Wonder how we make biocompatible InP core-shell structures with very sharp emission? Or interested in growing highly controllable NIR and SWIR InSb QDs? Then, follow the links below to see more.
1) Water-Soluble Alumina-Coated Indium Phosphide Core–Shell Quantum Dots with Efficient Deep-Red Emission Beyond 700 nm at Small
Solution-processed colloidal III-V semiconductor-based quantum dots (QDs) represent promising and environmentally-friendly alternatives to Cd-based QDs in the realms of optoelectronics and biological applications. While InP-based core–shell QDs have demonstrated efficient light-emitting diode (LED) performance in the visible region, achieving deep-red emission (above 700 nm) with a narrow linewidth has proven challenging. Herein, the study presents a novel strategy for synthesizing InP/ZnSe/ZnS core–shell–shell QDs tailored for emission in the first biological transparency window. The
resulting QDs exhibit an emission wavelength up to 725 nm with a narrow peak full width at half maximum (FWHM) down to 107 meV (45 nm). To enhance the biocompatibility and chemical stability of the QDs, their surface is further capped with a layer of amorphous alumina resulting in an InP/ZnSe/ZnS/Al2O3 heterostructure. This surface passivation not only ensures environmental- and photostability but also enhances the photoluminescence quantum yield (PLQY). The alumina capping enables the aqueous phase transfer via surface ligand exchange using mercaptopropionic acid (MPA) while maintaining the initial quantum yield. The resulting QDs demonstrate a significant potential for advancing next-generation optoelectronic technologies and bio-applications.
2) Synthesis of NIR/SWIR Absorbing InSb Nanocrystals Using Indium(I) Halide and Aminostibine Precursors at Advanced Functional Materials
Colloidal InSb quantum dots (QDs) are a potential alternative to toxic Pb- and Hg-chalcogenide QDs for covering the technologically important near-infrared/shortwave infrared (NIR/SWIR) spectral range. However, appropriate Sb precursors are scarce and obtaining narrow size distributions is challenging. Tris(dimethylamido)antimony (Sb(NMe2)3) is an appealing choice due to its commercial availability and non-pyrophoric character but implies the reduction of antimony from the +3 to the required –3 state. In reported works, strong reducing agents such as lithium triethylborohydride are used, which lead to the fast co-reduction of both Sb3+ and In3+. The downsides of this approach are reproducibility issues and the risk of forming metal nanoparticles due to the different reduction kinetics of Sb3+ and In3+. Here, indium(I) halides are explored as simultaneous indium source and mild reducing agent for the antimony precursor. The wavelength of the excitonic absorption peak of the phase-pure InSb QDs obtained with this approach can be tuned from 630 to 1890 nm, which corresponds to a size range of ≈2–7 nm. The synthesis can also be conducted in a heat-up manner, which facilitates the scale-up and paves the way for the use of InSb QDs in applications such as NIR/SWIR photodetectors, cameras, biological imaging, and telecommunications.
Congrats to Avijit, Ranjana and Céline, and Yongju and Oleksandra!
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