Aurelio Rossinelli1 Andreas Riedinger2 Philippe Knuesel1 Patricia Marqués Gallego1 Felipe Antolinez1 David Norris1

1, ETH Zurich, Zurich, , Switzerland
2, Max Planck Institute for Polymer Research, Mainz, , Germany

Colloidal nanoplatelets (NPLs) are quasi-two-dimensional nanocrystals with atomically precise thickness in one dimension. Due to their highly anisotropic shape, they offer favorable optical properties such as narrow emission linewidths and large absorption cross-sections.1,2 However, as-synthesized, NPLs exhibit poor photo- and chemical stability. Thus, strategies have been sought to improve their properties by adding a shell on the NPLs. For spherical quantum dots, recently developed recipes for growing high-quality shells are performed at high temperatures. However, to date, this strategy has not been extended to NPLs because of their low thermal stability compared to quantum dots.3 Here, we present a method for obtaining CdSe/CdS core/shell NPLs in which the shell is added at high temperatures (~300 °C).4 This enables the growth of uniform and thick CdS shells, which is not possible with existing continuous-growth protocols. We obtain high-quality monodisperse CdSe/CdS core/shell NPLs with narrow emission linewidths, high QYs, and suppressed blinking. Such samples exhibit emission peaks at 660-670 nm that can result in improvements for a wide range of applications in optics and optoelectronics relying on efficient and narrow red emitters.

1) S. Ithurria et al., Nat. Mater., 10, 936 (2011)
2) A. Yeltik et al., J. Phys. Chem. C, 119, 26768 (2015)
3) A. Riedinger et al., Nat. Mater., 16, 743 (2017)
4) A. A. Rossinelli et al., Chem. Commun., 53, 9938 (2017)