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Photoluminescence from quasi-type-II spherical CdSe-CdS core-shell quantum dots



Photoluminescence from quasi-type-II spherical CdSe-CdS core-shell quantum dots



Applied Optics 52(1): 105-109



Spherical CdSe-CdS core-shell quantum dots (QDs) are found to be flexible in the transition between the type-I regime and the type-II regime with different core/shell dimensions. The quasi-type-II feature of the colloidal dots is confirmed with time-resolved photoluminescence (PL) measurements. Two recombination paths of the excitons with significantly different decay rates are observed and analyzed. The spherical CdSe-CdS core-shell QDs are numerically simulated to investigate the carrier separation. A relatively long radiative lifetime and high degree of spatial carrier separation provide good potential to achieve lasing under continuous-wave excitation. Amplified spontaneous emission at room temperature is detected from the QDs embedded in the polymer matrix. It is shown that a larger shell thickness results in a lower pumping threshold, while a smaller shell thickness leads to higher PL efficiency.

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Accession: 054985504

Download citation: RISBibTeXText

PMID: 23292381

DOI: 10.1364/ao.52.000105


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