1 research outputs found
Origin of the Enhanced Photoluminescence Quantum Yield in MAPbBr<sub>3</sub> Perovskite with Reduced Crystal Size
Methylammonium
lead bromide perovskite (MAPbBr<sub>3</sub>) has
been widely investigated for applications in visible perovskite light-emitting
diodes (LEDs). Fine-tuning of the morphology and of the crystal size,
from the microscale down to the quantum confinement regime, has been
used to increase the photoluminescence quantum yield (PLQY). However,
the physical processes underlying the PL emission of this perovskite
remain unclear. Here, we elucidate the origin of the PL emission of
polycrystalline MAPbBr<sub>3</sub> thin films by different spectroscopic
techniques. We estimate the exciton binding energy, the reduced exciton
effective mass, and the trap density. Moreover, we confirm the coexistence
of free carriers and excitons, quantifying their relative population
and mutual interaction over a broad range of excitation densities.
Finally, the enhanced PLQY upon crystal size reduction to the micro-
and nanometer scale in the presence of additives is attributed to
favored excitonic recombination together with reduced surface trapping
thanks to efficient passivation by the additives