Dielectric Confinement Enables Molecular Coupling in Stacked Colloidal Nanoplatelets

Abstract

We show theoretically that carriers confined in semiconductor colloidal nanoplatelets (NPLs) sense the presence of neighbor, cofacially stacked NPLs in their energy spectrum. When approaching identical NPLs, the otherwise degenerate energy levels redshift and split, forming (for large stacks) minibands of several meV width. Unlike in epitaxial structures, the molecular behavior does not result from quantum tunneling but from changes in the dielectric confinement. The associated excitonic absorption spectrum shows a rich structure of bright and dark states, whose optical activity and multiplicity can be understood from reflection symmetry and Coulomb tunneling. We predict spectroscopic signatures which should confirm the formation of molecular states, whose practical realization would pave the way to the development of nanocrystal chemistry based on NPLs.

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• Fourier-imaging of single self-assembled CdSe nanoplatelet chains and clusters reveals out-of-plane dipole contribution
• Nature and Control of Shakeup Processes in Colloidal Nanoplatelets
• Enhanced robustness and dimensional crossover of superradiance in cuboidal nanocrystal superlattices
• Charging of colloidal nanoplatelets: effect of Coulomb repulsion on spin and optoelectronic properties