Synthesis of Off-State-Free InP-based Quantum Dots by Engineering of Charge Carrier Wavefunctions

Abstract

Impurities can be observed in the crude reaction solution of colloidal semiconductor nanocrystal quantum dots (QDs). Impurities must be eliminated from QDs before they can be used in optoelectronic devices or stored. However, because surface ligands are partially eliminated during purification, the purification stages frequently result in the formation of electronic traps. As a result, retaining the original quality of QDs after purification becomes extremely difficult. By engineering the charge carrier wavefunctions, we provide an approach for preserving the original quality of InP/ZnSe/ZnS QDs. we can effectively confine the wavefunctions of the charge carriers within the InP/ZnSe/ZnS QDs by inserting a thick ZnS shell layer, which acts as a huge electronic barrier. As a result, we make high-quality InP/ZnSe/ZnS QDs with reduced PL QY drop, whereas InP/ZnSe/ZnS QDs with a thin ZnS shell have a substantial decrease in PL QY after several purifying processes. Because of the reduced leakage of charge carriers, time-resolved spectroscopy and single dot spectroscopy experiments show that InP/ZnSe/ZnS QDs are substantially less impacted by surface traps. This observation is supported by theoretical understanding based on wavefunction calculations. Our approach provides a promising method for preserving the optoelectronic capabilities of QDs during purifying methods, improving their potential for a variety of applications.