Efficient and Bright Deep-Red Light-Emitting Diodes based on a Lateral 0D/3D Perovskite Heterostructure

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 Cs₄PbI₆/FA_xCs_{1- x}PbI₃ (0D/3D) heterostructure that can enable efficient deep-red perovskite LEDs at very high brightness is demonstrated. The Cs₄PbI₆ can facilitate the growth of low-defect FA_xCs_{1- 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.