Electric Field Dependent Photoluminescence Blinking of Single Hybrid CdSe/CdS-PMMA Quantum Dots
The Journal of Physical Chemistry C , Volume 125, pp 15384-15395; https://doi.org/10.1021/acs.jpcc.1c01438
Abstract: Single CdSe/CdS quantum dots have been embedded into a polymer (poly(methyl methacrylate), PMMA) nanoparticle of about 50 nm diameter. The influence of external electric AC fields on photoluminescence blinking dynamics has been investigated as a function of field strengths up to 800 kV cm–1 and field frequencies up to 5 kHz. Detailed blinking analysis is carried out by truncated power laws. They are interpreted within the framework of the electric field dependent dielectric response of the PMMA nanoparticle acting as the quantum dots local nanoenvironment. Subsequent to the creation of an exciton, the hole is eventually trapped at the QD interface and the electron is ejected into PMMA, creating a local dipolar reaction field. A competition between electric field induced polarization and electric dipole orientation of the reaction field modifies trap depths for charges and thus blinking dynamics. The frequency dependence of blinking indicates a broad distribution of electric dipolar relaxation times centered at 100 ms. To account for such a relaxation in PMMA at room temperature, we propose a close relation to the β-relaxation of PMMA.
Keywords: blinking / PMMA / electric field / photoluminescence / trapped / CdSe/CdS / relaxation / function / dipolar
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