Lateral quantum confinement regulates charge carrier transfer and biexciton interaction in CdSe/CdSeS core/crown nanoplatelets

TL;DR

This study investigates how lateral quantum confinement in CdSe/CdSeS nanoplatelets influences charge transfer rates and biexciton interactions, revealing tunable dynamics crucial for optoelectronic applications.

Contribution

It demonstrates that fine-tuning core size and lateral confinement controls charge transfer and biexciton binding energy in core/crown nanoplatelets, offering new insights into their optoelectronic behavior.

Findings

Charge transfer rate varies by an order of magnitude with core size.

Carrier blocking mechanism hinders further transfer when carriers are filled.

Biexciton binding energy exhibits non-monotonic dependence on emission wavelength.

Abstract

Charge carrier dynamics essentially determine the performance of various optoelectronic applications of colloidal semiconductor nanocrystals. Among them, two-dimensional nanoplatelets provide new adjustment freedom for their unique core/crown heterostructure. Herein, we demonstrate that by fine-tuning the core size and the lateral quantum confinement, the charge carrier transfer rate from the crown to the core can be varied by one order of magnitude in CdSe/CdSeS core/alloy-crown nanoplatelets. In addition, the transfer can be affected by a carrier blocking mechanism, i.e., the filled carriers hinder further possible transfer. Furthermore, we found that the biexciton interaction is oppositely affected by quantum confinement and electron delocalization, resulting in a non-monotonic variation of the biexciton binding energy with the emission wavelength. This work provides new observations and insights into the charge carrier transfer dynamics and exciton interactions in colloidal nanoplatelets and will promote their further applications in lasing, display, sensing, etc.