2 research outputs found
Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr<sub>3</sub> Perovskite Nanocrystals
Perovskite semiconductors
have emerged as a promising class of
materials for optoelectronic applications. Their favorable device
performances can be partly justified by the defect tolerance that
originates from their electronic structure. The effect of this inherent
defect tolerance, namely the absence of deep trap states, on the photoluminescence
(PL) of perovskite nanocrystals (NCs) is currently not well understood.
The PL emission of NCs fluctuates in time according to power law kinetics
(PL intermittency, or blinking), a phenomenon that has been explored
over the past two decades in a vast array of nanocrystal (NC) materials.
The kinetics of the blinking process in perovskite NCs have not been
widely explored. Here, PL trajectories of individual orthorhombic
cesium lead bromide (CsPbBr<sub>3</sub>) perovskite NCs are measured
using a range of excitation intensities. The power law kinetics of
the bright NC state are observed to truncate exponentially at long
durations, with a truncation time that decreases with increasing intensity
before saturating at an intensity corresponding to an average formation
of a single exciton. The results indicate that a diffusion-controlled
electron transfer (DCET) mechanism is the most likely charge trapping
process, while Auger autoionization plays a lesser role. The relevance
of the multiple recombination centers (MRC) model to the results presented
here cannot be ascertained, since the underlying switching mechanism
is not currently available. Further experimentation and theoretical
work are needed to gain a comprehensive understanding of the photophysics
in these emerging materials
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Highly Luminescent Colloidal Nanoplates of Perovskite Cesium Lead Halide and Their Oriented Assemblies
Anisotropic colloidal quasi-two-dimensional
nanoplates (NPLs) hold
great promise as functional materials due to their combination of
low dimensional optoelectronic properties and versatility through
colloidal synthesis. Recently, lead-halide perovskites have emerged
as important optoelectronic materials with excellent efficiencies
in photovoltaic and light-emitting applications. Here we report the
synthesis of quantum confined all inorganic cesium lead halide nanoplates
in the perovskite crystal structure that are also highly luminescent
(PLQY 84%). The controllable self-assembly of nanoplates either into
stacked columnar phases or crystallographic-oriented thin-sheet structures
is demonstrated. The broad accessible emission range, high native
quantum yields, and ease of self-assembly make perovskite NPLs an
ideal platform for fundamental optoelectronic studies and the investigation
of future devices