Room-Temperature Polariton Lasing in All-Inorganic Perovskite Nanoplatelets

Polariton lasing is the coherent emission arising from a macroscopic polariton condensate first proposed in 1996. Over the past two decades, polariton lasing has been demonstrated in a few inorganic and organic semiconductors in both low and room temperatures. Polariton lasing in inorganic materials significantly relies on sophisticated epitaxial growth of crystalline gain medium layers sandwiched by two distributed Bragg reflectors in which combating the built-in strain and mismatched thermal properties is nontrivial. On the other hand, organic active media usually suffer from large threshold density and weak nonlinearity due to the Frenkel exciton nature. Further development of polariton lasing toward technologically significant applications demand more accessible materials, ease of device fabrication, and broadly tunable emission at room temperature. Herein, we report the experimental realization of room-temperature polariton lasing based on an epitaxy-free all-inorganic cesium lead chloride perovskite nanoplatelet microcavity. Polariton lasing is unambiguously evidenced by a superlinear power dependence, macroscopic ground-state occupation, blueshift of the ground-state emission, narrowing of the line width and the buildup of long-range spatial coherence. Our work suggests considerable promise of lead halide perovskites toward large-area, low-cost, high-performance room-temperature polariton devices and coherent light sources extending from the ultraviolet to near-infrared range

Optically Pumped Polaritons in Perovskite Light-Emitting Diodes

Lead halide perovskites have achieved significant progress in light-emitting diodes (LEDs) with high efficiency in the past few decades. They are also ideal candidates for reaching the strong exciton–photon coupling regime due to their large exciton binding energy and oscillator strength. The generation and control of exotic phenomena in perovskite electroluminescent microcavities, such as electrically pumped polariton lasing and polariton LEDs, operating in the strong coupling regime at room temperature, is still a great challenge. Here, we demonstrate room-temperature strong coupling in a perovskite LED structure. The best device shows a current efficiency of 4.5 cd/A and an external quantum efficiency of 1.4% while exhibiting anticrossing behavior via optical pumping. Our approach represents a new strategy to explore ultrafast LEDs as well as electrically pumped perovskite lasing

Nonreciprocal bandstructures in an exciton-polariton Floquet optical lattice

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