Aliovalent Doping in Colloidal Quantum Dots and Its Manifestation on Their Optical Properties: Surface Attachment versus Structural Incorporation

Abstract

Doping colloidal quantum dots (CQDs) with aliovalent cations is a promising, yet underexplored, approach to control the optoelectronic properties in CQDs. In CQD doping, kinetics determine whether a dopant element will incorporate into the host crystal structure, while thermodynamics dictate the mechanism of dopant incorporation. Here, we show that those mechanisms can be readily monitored by simple optical measurements and XRD studies in CQD ensembles. Based on this, we outline the critical role of dopant solubility limit in CQD doping, bridging the gap between nanocrystalline and bulk semiconductors. Finally, we present a combined simulation and X-ray absorption fine structure (XAFS) data study to shed new insights on the origin of charge compensation upon doping in CQD materials that has, thus far, limited high doping efficacy, even under efficient dopant incorporation schemes.