Coupled Colloidal Quantum Dot Molecules

TL;DR

This paper demonstrates the synthesis and analysis of coupled semiconductor nanocrystal molecules, revealing their structural, electronic, and quantum mechanical properties, with potential applications in quantum technologies and sensing.

Contribution

It introduces a method to create and analyze coupled nanocrystal molecules, combining experimental fusion techniques with quantum mechanical simulations.

Findings

Successful formation of CdSe/CdS nanocrystal dimers

Observation of band gap red shift indicating coherent coupling

Identification of fusion scenarios at the atomic level

Abstract

Coupling of atoms is the basis of chemistry, yielding the beauty and richness of molecules. We utilize semiconductor nanocrystals as artificial atoms to form nanocrystal molecules that are structurally and electronically coupled. CdSe/CdS core/shell nanocrystals are linked to form dimers which are then fused via constrained oriented attachment. The possible nanocrystal facets in which such fusion takes place are analyzed with atomic resolution revealing the distribution of possible crystal fusion scenarios. Coherent coupling and wavefunction hybridization are manifested by a red shift of the band gap, in agreement with quantum mechanical simulations. Single nanoparticle spectroscopy unravels the attributes of coupled nanocrystal dimers related to the unique combination of quantum mechanical tunneling and energy transfer mechanisms. This sets the stage for nanocrystals chemistry to yield a diverse selection of coupled nanocrystal molecules constructed from controlled core/shell nanocrystal building blocks. These are of direct relevance for numerous applications in displays, sensing, biological tagging and emerging quantum technologies.