Tailoring Excitons, Biexcitons, and Trions Dynamics in CdSe/CdS Dot-in-Rod Nanomaterials for Light-Emitting Devices

Abstract CdSe-based core−shell nanomaterials offer the possibility of manipulating exciton dynamics and multi-exciton interactions by controlling the core and shell morphologies. In this context, CdSe/CdS dot-in-rod nanostructure (DiR) has emerged as an interesting class of nanomaterials for application in light-emitting devices, with large absorption cross-section, polarized emission, and reduced Auger recombination rate. Furthermore, the rod-shaped shell allows for extra degrees of freedom, compared to the spherical-shaped ones, to control exciton and multi-excitons dynamics. In this study, we perform a comprehensive analysis of the influence of the structural parameters, including the core diameter, shell diameter and length, and core position within the shell, on the exciton dynamics and multi-exciton interactions in CdSe/CdS DiRs. We show that single exciton and negative trion dynamics are more sensitive to the shell dimensions, while the biexciton dynamics is mostly governed by the core size. Additionally, we show that the core position within the rod-shaped shell also influences the carriers’ dynamics, reducing the recombination rate as the core moves away from the center of the nanorod, suggesting that, near the edges of the nanorods, the overlap between electron and hole wavefunctions is reduced, possibly due to the presence of surface charges, which could create a net permanent electric field.