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Synthesis of near unity photoluminescence CdSeTe alloyed Quantum Dots
摘要： Quantum dots (QD) tend to exhibit low photoluminescence (PL) properties due to long hanging ligands on their surface and steric barriers resulting therefrom. On the other hand, in order to be used in QD LED and QDSSC technologies, highly intense PL characteristics and PL lifetime are required respectively. Therefore, this study focuses on increasing the PL QY and PL lifetime of CdSeTe alloy QDs. To achieve this aim, CdSeTe alloy QDs synthesized by organometallic method were treated with different mass % (m/m) chloride solution. The PL Quantum Yield (PL QY) of CdSeTe alloy QDs, which was 13.2 ± 2.0% before treatment, increased to 97.4 ± 2.0% after treatment with 60% CdCl2 solution approaching to almost unity value. In addition to the increase in PL QY, PL lifetime increased from 28 ns to 33 ns with chloride treatment. However, thanks to surface passivation, the time to fall to half the value of PL QY for treated CdSeTe(Cl) QDs under oxygen exposure was increased from 10 h to 64 h. In the study, the absorbance and emission characterizations of CdSeTe alloy QDs treated with chloride and untreated, were presented.
关键词： Quantum dot,Photo luminescence,CdSeTe,Chloride treatment,Quantum yield
更新于2025-11-14 15:24:45
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Exfoliation behavior of van der Waals strings: case study of Bi <sub/>2</sub> S <sub/>3</sub>
摘要： The family of crystals constituting covalently bound strings, held together by van der Waals forces, can be exfoliated into smaller entities, similar to crystals made of van der Waals sheets. Depending on the anisotropy of such crystals, and the spacing between their strings in each direction, van der Waals sheets or ribbons can be obtained after the exfoliation process. In this work, we demonstrate that ultra-thin nanoribbons of bismuth sulfide (Bi2S3) can be synthesized via a high power sonication process. The thickness and width of these ribbons are governed by the van der Waals spacings around the strings within the parent crystal. The lengths of the nanoribbons are initially limited by the dimensions of the starting bulk particles. Interestingly, these nanoribbons change stoichiometry, composition and are elongated when the duration of agitation increases, due to Ostwald ripening. An application of the exfoliated van der Waals strings is presented for optical biosensing using photoluminescence of Bi2S3 nanoribbons, reaching detection limits of less than 10 nM L-1 in response to bovine serum albumin. The concept of exfoliating van der Waals strings could be extended to a large class of crystals for creating bodies ranging from sheets to strings, with optoelectronic properties different from that of their bulk counterparts.
关键词： bio-sensing,photo luminescence,van der Waals strings,bismuth sulfide,liquid phase exfoliation,Bi2S3,Ostwald ripening
更新于2025-09-10 09:29:36