LAUSR

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 three-dimensional perovskites. Here, we demonstrate a lateral Cs4 PbI6 /FAx Cs1- x PbI3 (zero-dimensional/three-dimensional, 0D/3D) heterostructure, which can enable efficient deep-red perovskite LEDs at very high brightness. 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. Our 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. Our LEDs are suitable for pulse oximeters, showing an error <2% of blood oxygen saturation compared with commercial oximeters. This article is protected by copyright. All rights reserved.