Inorganic perovskite lasers are of particular interest, with much recent work focusing on Fabry-Pérot cavity-forming nanowires. We demonstrate the direct observation of lasing from transverse electromagnetic (TEM) modes with a long coherence time ∼ 9.5 ps in coupled CsPbBr3 quantum dots, which dispense with an external cavity resonator and show how the wavelength of the modes can be controlled via two independent tuning-mechanisms. Controlling the pump power allowed us to fine-tune the TEM mode structure to the emission wavelength, thus providing a degree of control over the properties of the lasing signal. The temperature-tuning provided an additional degree of control over the wavelength of the lasing peak, importantly, maintained a constant full width at half maximum (FWHM) over the entire tuning range without mode-hopping.
The surprising recent
observation of highly emissive triplet-states
in lead halide perovskites accounts for their orders-of-magnitude
brighter optical signals and high quantum efficiencies compared to
other semiconductors. This makes them attractive for future optoelectronic
applications, especially in bright low-threshold nanolasers. While
nonresonantly pumped lasing from all-inorganic lead-halide perovskites
is now well-established as an attractive pathway to scalable low-power
laser sources for nano-optoelectronics, here we showcase a resonant
optical pumping scheme on a fast triplet-state in CsPbBr
3
nanocrystals. The scheme allows us to realize a polarized triplet-laser
source that dramatically enhances the coherent signal by 1 order of
magnitude while suppressing noncoherent contributions. The result
is a source with highly attractive technological characteristics,
including a bright and polarized signal and a high stimulated-to-spontaneous
emission signal contrast that can be filtered to enhance spectral
purity. The emission is generated by pumping selectively on a weakly
confined excitonic state with a Bohr radius ∼10 nm in the nanocrystals.
The exciton fine-structure is revealed by the energy-splitting resulting
from confinement in nanocrystals with tetragonal symmetry. We use
a linear polarizer to resolve 2-fold nondegenerate sublevels in the
triplet exciton and use photoluminescence excitation spectroscopy
to determine the energy of the state before pumping it resonantly.
Controlling or passivating the surface defects in perovskite materials is a key parameter to enhance the high photoluminescence quantum efficiency. An enhanced quantum efficiency for perovskite MAPbBr3 (MA = methylammonium) nanocrystals was demonstrated by encapsulating the MAPbBr3 with graphene (Gr) arising from defect passivation, a conclusion supported by density functional theory calculations.
This is a repository copy of Purcell enhancement of a deterministically coupled quantum dot in an SU-8 laser patterned photonic crystal heterostructure.
The effect of surface passivation on the photoluminescence (PL) emitted by CsPbBr3 micro/nano‐rods coated with Pb(OH)2 is investigated, where a high quantum yield and excellent stability for the emission are found. The CsPbBr3/Pb(OH)2 rods generally present a peak that is blue shifted compared to that seen in rods without a hydroxide cladding at low temperatures. By increasing the temperature, it is further shown that the passivated surface states are very robust against thermal effects and that the PL peak intensity only drops by a factor of 1.5. Localized stimulated emission at defect states found within larger rods is also demonstrated, clarified by spatially resolved confocal PL mapping along the length of the rods. The diffusion parameter of the carrier density distribution is measured to be 5.70 µm for the sky‐blue emission, whereas for the defect lasing site it is found to be smaller than this excitation spot size.
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