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Colloidal PbS/PbCl2 core/shell nanoplatelets were synthesized via wet-chemical methods using lead oleate and lead chloride as lead precursors. The resulting heterostructures consist of a PbS core, a PbCl2 shell, and an intermediate layer of lead sulfochloride alloy. These nanoplatelets exhibit a photoluminescence quantum yield of approximately 20%, nearly an order of magnitude higher than that of unshelled PbS nanoplatelets. Cyclic voltammetry measurements reveal a type-I band alignment between the core and shell. Despite the presence of strong attractive biexciton Auger recombination, as observed in transient absorption spectroscopy, the nanoplatelets achieve amplified spontaneous emission at a low pump threshold of 76 μJ cm–2. Their large lateral dimensions support the spatial distribution of multiple excitons, including repulsive biexcitons, enabling efficient light amplification.more » « lessFree, publicly-accessible full text available August 27, 2026
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In the synthesis of colloidal PbS nanosheets, the supernatant of the reaction solution is reused to boost the lead conversion efficiency. It doubles the conversion efficiency of the lead precursors to the PbS nanosheets. The nanosheets synthesized by reusing the supernatant have similar morphology, nearly identical thickness, and optical properties as the original ones, confirmed by transmission electron microscopy, X‐ray diffraction, and photoluminescence spectroscopy. This method reduces the toxic Pb‐containing waste during the synthesis, a step toward the green and scalable synthesis of colloidal 2D PbS nanosheets.more » « less
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Abstract By changing the precursor lead‐to‐sulfur molar ratio in the synthesis of colloidal PbS nanosheets, the lateral size of the nanosheet can be tuned in a wide range from 100 nm to 1500 nm while keeping its thickness around 2.4 nm. Using chloroalkane molecules with a long carbon‐chain as the capping ligands can further reduce the lateral size down to 20 nm. The concentration of the chloroalkane in the reaction solution and the reaction temperature also have significant effects on the lateral size. At room temperature, nanosheets with a small lateral size exhibit a narrow light‐emission linewidth. The same nanosheets also show a sharp exciton peak near the band edge in the optical absorption spectrum.more » « less
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