![]() ![]() ![]() Second, we develop a photophysical fitting model to determine the Auger lifetime of the simplest charged states in Si NCs: the negative (t X -) and positive (t X +) trions. We show that this method can be used to determine the presence of free carriers for any doped NC system, regardless of the presence/absence of defect channels in the carrier dynamics. First, we monitor the AR of charge-neutral multiexcitons by measuring the biexciton lifetime (t XX) as a function of the NC size and doping configuration. We expand the study over more » a large NC size range (D NC ~ 3-8 nm), in which n- and p-type doping is achieved by either a substitutional or surface doping effect, respectively. In this study, we investigate AR decay of non-thermal plasma-produced n- and p-type-doped Si NCs. However, such an analysis has remained elusive for indirect band gap Si NCs. To this end, extensive experimental studies on direct band gap NCs have investigated the trion components (both positive and negative) that construct the total AR rate. Consequently, it complicates the practical realization of many semiconductor nanocrystal (NC)-based devices such as light-emitting diodes, photovoltaic cells, and single-photon emitters, in which charged exciton states often occur. ![]() Nonradiative Auger recombination (AR) tends to dominate carrier dynamics in charged, quantum-confined structures. Our findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states, suggesting its generality to quantum-confined nanocrystals of arbitrary compositions and complexities. Furthermore, by comparing the measurements on the QDs with the “sharp” versus “smooth” interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive more » trion pathways. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdS QDs with two distinct core/shell interfacial profiles (“sharp” versus “smooth”). Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. ![]()
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