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