The application of colloidal semiconductor quantum dots as single-dot light sources still requires several challenges to be overcome. Recently, there has been considerable progress in suppressing intensity fluctuations (blinking) by encapsulating an emitting core in a thick protective shell. However, these nanostructures still show considerable fluctuations in both emission energy and linewidth. Here we demonstrate type-I core/shell heterostructures that overcome these deficiencies. They are made by combining wurtzite semiconductors with a large, directionally anisotropic lattice mismatch, which results in strong asymmetric compression of the emitting core. This modifies the structure of band-edge excitonic states and leads to accelerated radiative decay, reduced exciton–phonon interactions, and suppressed coupling to the fluctuating electrostatic environment. As a result, individual asymmetrically strained dots exhibit highly stable emission energy (<1 meV standard deviation) and a subthermal room-temperature linewidth (~20 meV), concurrent with nearly nonblinking behaviour, high emission quantum yields, and a widely tunable emission colour.
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V.I.K. and Y.-S.P. were supported by the Solar Photochemistry Program of the Chemical Sciences, Biosciences and Geosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy. J.L. acknowledges support by the Laboratory Directed Research and Development Program at Los Alamos National Laboratory.
The authors declare no competing interests.
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Supplementary Sections 1,2, Supplementary Figures 1–7, Supplementary Table 1, Supplementary References 1–10
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