Thickness-Dependence of Exciton–Exciton Annihilationin Halide Perovskite Nanoplatelets
2020
Exciton–exciton
annihilation (EEA) and Auger recombination
are detrimental processes occurring in semiconductor optoelectronic
devices at high carrier densities. Despite constituting one of the
main obstacles for realizing lasing in semiconductor nanocrystals
(NCs), the dependencies on NC size are not fully understood, especially
for those with both weakly and strongly confined dimensions. Here,
we use differential transmission spectroscopy to investigate the dependence
of EEA on the physical dimensions of thickness-controlled 2D halide
perovskite nanoplatelets (NPls). We find the EEA lifetimes to be extremely
short on the order of 7–60 ps. Moreover, they are strongly
determined by the NPl thickness with a power law dependence according
to τ2 ∝ d5.3.
Additional measurements show that the EEA lifetimes also increase
for NPls with larger lateral dimensions. These results show that a
precise control of the physical dimensions is critical for deciphering
the fundamental laws governing the process especially in 1D and 2D
NCs.
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