Bright and efficient deep-red light-emitting diodes (LEDs) are important for applications in medical therapy and biological imaging due to the high penetration of deep-red photons into human tissues. Metal-halide perovskites have potential to achieve bright and efficient electroluminescence due to their favorable optoelectronic properties. However, efficient and bright perovskite-based deep-red LEDs have not been achieved yet, due to either Auger recombination in low-dimensional perovskites or trap-assisted nonradiative recombination in 3D perovskites. Here, a lateral Cs4 PbI6 /FAx Cs1- x PbI3 (0D/3D) heterostructure that can enable efficient deep-red perovskite LEDs at very high brightness is demonstrated. The Cs4 PbI6 can facilitate the growth of low-defect FAx Cs1- x PbI3 , and act as low-refractive-index grids, which can simultaneously reduce nonradiative recombination and enhance light extraction. This device reaches a peak external quantum efficiency of 21.0% at a photon flux of 1.75 × 1021 m-2 s-1 , which is almost two orders of magnitude higher than that of reported high-efficiency deep-red perovskite LEDs. Theses LEDs are suitable for pulse oximeters, showing an error <2% of blood oxygen saturation compared with commercial oximeters.
Keywords: 0D/3D perovskite heterostructure; deep-red perovskite light-emitting diodes; efficiency; oximeters.
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