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

Liu, Yongjie; Tao, Chen; Cao, Yu; Chen, Liangyan; Wang, Shuxin; Li, Pei; Wang, Cheng; Liu, Chenwei et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Formamidinium lead iodide (FAPbI<sub>3</sub>) 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<sub>3</sub> 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 δ-FAPbI<sub>3</sub>, two-dimensional FA<sub>2</sub>FA<sub>n-1</sub>Pb<sub>n</sub>I<sub>3n+1</sub>, and three-dimensional α-FAPbI<sub>3</sub>, 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<sub>3</sub>-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.