Suppression of Auger Processes in Confined Structures

Abstract

We explore how the size and shape of the microscopic confinement potential affects the nonradiative Auger decay rate of confined carriers. Calculations conducted in the two-band, effective mass Kane model unambiguously show that smoothing out the confinement potential could reduce the rate by more than 3 orders of magnitude relative to the rate in structures with abruptly terminating boundaries. As the confinement potential width is increased, the calculated rate decreases overall, exhibiting very deep minima at regular widths. Such minima suggest that nanocrystals of "magic sizes" can exist for which nonradiative Auger processes are strongly suppressed.

Interfacial engineering of core/shell heterostructured nanocrystal quantum dots for light-emitting applications

“…Cragg and Efros first predicted that the smooth potential changes from the core to the shell can diminish the AR rates by three orders of magnitude (Figure 3(a)) [31]. Later, Climente et al [32] further supported the effects of the potential profiles across the interface on the AR rates in heterostructured NQDs.…”

“…In heterostructured NQDs, the potential shape (smooth vs. sharp) of the interfaces has a significant impact on AR (Figure 3(a,b)) [26,28,29,31,32,47]. Cragg and Efros first predicted that the smooth potential changes from the core to the shell can diminish the AR rates by three orders of magnitude (Figure 3(a)) [31].…”

“…Specifically, the structural formulation at the core-shell interface affects the formation of misfit defects that are efficient non-radiative recombination centers [21][22][23][24]27,30]. In addition, the potential profiles across the interfaces influence the Auger recombination (AR) rates [28,29,31,32]. Beyond gaining photophysical insights into the structure-property relationship, the advances in interfacial engineering have enabled the control of the optical properties of core/shell heterostructured NQDs and have led to substantial advances in their applications [5,24,33].…”

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

“…The momentum selection rule is therefore not so strict in a NC. Consequently, the Auger process can be much faster, depending on the overlap between charge carrier wavefunctions in momentum space [224,225] Top Curr Chem (Z) (2016) 374:58 Page 13 of 30 58 properties of trions on the single-NC level [72,[206][207][208]. However, this method is only applicable to NCs where the trion state luminescence can be clearly distinguished from the neutral exciton luminescence.…”

“…The most commonly studied hetero-NC composition for reduced Auger losses is CdSe/CdS in various shapes and sizes [72,84,206,[221][222][223]. It was first predicted theoretically [224,225] and later confirmed experimentally [84,[221][222][223] that an alloyed coreshell interface leads to suppressed Auger recombination. An alloyed heterointerface creates a smooth confinement potential for charge carriers in which highmomentum components in the wavefunctions are reduced in amplitude (see Fig.…”