期刊
CRYSTALS
卷 11, 期 11, 页码 -出版社
MDPI
DOI: 10.3390/cryst11111284
关键词
quantum dots; time-resolved spectroscopy
资金
- NSF [HRD-1137747]
- ARO [W911NF-11-1-0177]
- NASA [NNX15AQ03A]
- National Institutes of Health (NIH) [R01EB12003]
- NASA [NNX15AQ03A, 802892] Funding Source: Federal RePORTER
The broadband spontaneous emission of excitons in CdSe quantum dots is of great interest for spectral imaging in living organisms or in the near infrared spectral region. As the dot size decreases, the role of surface-trapped states increases, introducing new electronic transitions.
The broadband spontaneous emission of excitons in CdSe quantum dots (QDs) is of great interest for the spectral imaging of living organisms or specific substances in the visible spectral region as well as in the biological optical window near the infrared spectral region. Semiconductor QDs that are near the bulk Bohr radius exhibit wide spectral tunability and high color purity due to quantum confinement of excitons within the dot boundary. However, with reducing dot size, the role of the surface-trapped state increases. The temperature-dependent photoluminescence (PL) confirms this with a ~3:1 emission intensity decrease from the surface-trapped state compared to the band edge. Large crystal irregularity, dangling ions, and foreign molecules can introduce new electronic transitions from surface-trapped states that provide broad spontaneous emission in the spectral region from visible to near IR in addition to the band edge emission. The time-resolved PL analyzed the fractional contributions of band edge, surface-trapped states, and possible intermediate trapped states to the broad spectral emission in order to characterize the CdSe QDs.
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