Time-Resolved and Temperature-Dependent Fractional Amplitude Contributions to the Broadband Emission of CdSe Quantum Dots
Quinton Rice,
Sangram Raut,
Kyle Burney,
Zygmunt Gryczynski,
Ignacy Gryczynski,
William W. Yu,
Bagher Tabibi,
Jaetae Seo
Affiliations
Quinton Rice
Advanced Center for Laser Science and Spectroscopy, Department of Physics, Hampton University, Hampton, VA 23668, USA
Sangram Raut
Center for Fluorescence Technologies and Nanomedicine, Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
Kyle Burney
Advanced Center for Laser Science and Spectroscopy, Department of Physics, Hampton University, Hampton, VA 23668, USA
Zygmunt Gryczynski
Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129, USA
Ignacy Gryczynski
Center for Fluorescence Technologies and Nanomedicine, Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
William W. Yu
Department of Chemistry and Physics, Louisiana State University, Shreveport, LA 71115, USA
Bagher Tabibi
Advanced Center for Laser Science and Spectroscopy, Department of Physics, Hampton University, Hampton, VA 23668, USA
Jaetae Seo
Advanced Center for Laser Science and Spectroscopy, Department of Physics, Hampton University, Hampton, VA 23668, USA
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.
