Pursuing Band-like Transport in Colloidal Quantum Dot Assemblies

Abstract

Charge-carrier transport in semiconductor colloidal quantum dot (CQD) solids has been the subject of extensive debate and investigation for more than a decade. Understanding the underlying transport mechanisms in CQD assemblies is critical for unlocking their full potential in optoelectronic applications. To date, a widely accepted view holds that carrier transport in conventional ligand-capped glassy CQD solids is a non-adiabatic hopping process, supported by both experimental observations and theoretical models. In contrast, recent advances have enabled the self-assembly of CQDs into long-range-ordered superlattices with epitaxial connections between neighboring QDs. These superlattices are expected by many to exhibit band-like transport, potentially overcoming the limitations of hopping conduction in disordered systems. However, definitive experimental evidence and a comprehensive theoretical framework for charge transport in such highly ordered structures remain lacking. While the formation mechanisms of these superlattices have been widely explored, this Perspective aims to provide insight into the current understanding of charge-carrier transport in epitaxially connected CQD superlattices.