Synergistic passivation and stepped-dimensional perovskite analogs enable high-efficiency near-infrared light-emitting diodes

Formamidinium lead iodide (FAPbI(3)) perovskites are promising emitters for near-infrared light-emitting diodes. However, their performance is still limited by defect-assisted nonradiative recombination and band offset-induced carrier aggregation at the interface. Herein, we introduce a couple of cadmium salts with acetate or halide anion into the FAPbI(3) perovskite precursors to synergistically passivate the material defects and optimize the device band structure. Particularly, the perovskite analogs, containing zero-dimensional formamidinium cadmium iodide, one-dimensional delta-FAPbI(3), two-dimensional FA(2)FA(n-1)Pb(n)I(3n+1), and three-dimensional alpha-FAPbI(3), can be obtained in one pot and play a pivotal and positive role in energy transfer in the formamidinium iodide-rich lead-based perovskite films. As a result, the near-infrared FAPbI(3)-based devices deliver a maximum external quantum efficiency of 24.1% together with substantially improved operational stability. Combining our findings on defect passivation and energy transfer, we also achieve near-infrared light communication with device twins of light emitting and unprecedented self-driven detection. Defect-assisted nonradiative recombination and carrier aggregation at the interface hinder the potential of perovskites as emitter for light-emitting diodes. Here, Fang et al. achieve an external quantum efficiency of 24.1% by combining multidimensional perovskite with cascade conduction bands.