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Enhanced Emission from Bright Excitons in Asymmetrically Strained Colloidal CdSe/CdxZn1–xSe Quantum Dots

Journal Article · · ACS Nano
Colloidal CdSe quantum dots (QDs) designed with a high degree of asymmetric internal strain have recently been shown to host a number of desirable optical properties including subthermal room-temperature line widths, suppressed spectral diffusion, and high photoluminescence (PL) quantum yields. It remains an open question, however, whether they are well-suited for applications requiring emission of identical single photons. Here we measure the low-temperature PL dynamics and the polarization-resolved fluorescence line narrowing spectra from ensembles of these strained QDs. Our spectroscopy reveals the radiative recombination rates of bright and dark excitons, the relaxation rate between the two, and the energy spectra of the quantized acoustic phonons in the QDs that can contribute to relaxation processes. In comparison to conventional colloidal CdSe/ZnS core/shell QDs, we find that in asymmetrically strained CdSe QDs over six times more light is emitted directly by the bright exciton. Furthermore, these results are therefore encouraging for the prospects of chemically synthesized colloidal QDs as emitters of single indistinguishable photons.
Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
LDRD; USDOE
Grant/Contract Number:
89233218CNA000001
OSTI ID:
1822763
Report Number(s):
LA-UR--21-23484
Journal Information:
ACS Nano, Journal Name: ACS Nano Journal Issue: 9 Vol. 15; ISSN 1936-0851
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English

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