All-inorganic cesium lead bromide (CsPbBr 3 ) perovskite quantum dots (QDs) have recently emerged as highly promising solution-processed materials for nextgeneration light-emitting applications. They combine the advantages of QD and perovskite materials, which makes them an attractive platform for achieving high optical gain with high stability. Here, we report an ultralow lasing threshold (0.39 μJ/cm 2 ) from a hybrid vertical cavity surface emitting laser (VCSEL) structure consisting of a CsPbBr 3 QD thin film and two highly reflective distributed Bragg reflectors (DBRs). Temperature dependence of the lasing threshold and longterm stability of the device were also characterized. Notably, the CsPbBr 3 QDs provide superior stability and enable stable device operation over 5 h/1.8 × 10 7 optical pulse excitations under ambient conditions. This work demonstrates the significant potential of CsPbBr 3 perovskite QD VCSELs for highly reliable lasers, capable of operating in the short-pulse (femtosecond) and quasi-continuous-wave (nanosecond) regimes.
Perovskite light-emitting
diodes (PeLEDs) have undergone rapid
development in the last several years with external quantum efficiencies
(EQEs) reaching over 21%. However, most PeLEDs still suffer from severe
efficiency roll-off (droop) at high injection current densities, thus
limiting their achievable brightness and presenting a challenge to
their use in laser diode applications. In this work, we show that
the roll-off characteristics of PeLEDs are affected by a combination
of charge injection imbalance, nonradiative Auger recombination, and
Joule heating. To realize ultrabright and efficient PeLEDs, several
strategies have been applied. First, we designed an energy ladder
to balance the electron and hole transport. Second, we optimized perovskite
materials to possess reduced Auger recombination rates and improved
carrier mobility. Third, we replaced glass substrates with sapphire
substrates to better dissipate joule heat. Finally, by applying a
current-focusing architecture, we achieved PeLEDs with a record luminance
of 7.6 Mcd/m2. The devices can be operated at very high
current densities (J) up to ∼1 kA/cm2. Our work suggests a broad application prospect of perovskite materials
for high-brightness LEDs and ultimately a potential for solution-processed
electrically pumped laser diodes.
Metal
halide perovskites are emerging as attractive materials for
light-emitting diode (LED) applications. The external quantum efficiency
(EQE) has experienced a rapid progress and reached over 21%, comparable
to the state of the art organic and quantum dot LEDs. For metal halide
perovskites, their simple solution-processing preparation, facile
band gap tunability, and narrow emission line width provide another
attractive route to harness their superior optoelectronic properties
for multicolor display applications. In this work, we demonstrate
a high-resolution, large-scale photolithographic method to pattern
multicolor perovskite films. This approach is based on a dry lift-off
process which involves the use of parylene as an intermediary and
the easy mechanical peeling-off of parylene films on various substrates.
Using this approach, we successfully fabricated multicolor patterns
with red and green perovskite pixels on a single substrate, which
could be further applied in liquid crystal displays (LCDs) with blue
backlight. Besides, a prototype green perovskite micro-LED display
under current driving has been demonstrated.
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