Improving the efficiency of near-IR perovskite LEDs via surface passivation and ultrathin interfacial layers

Near-infrared light-emitting diodes (NIR-LEDs) are widely used in night vision, sensors, medicine, security, telecommunications, and military applications. Methyl-ammonium lead iodide (MAPbI3) is a promising material for realizing high-performance NIR-LEDs because of its high color purity, low non-radiative recombination rates, and tunable band gap. However, the development of MAPbI3-based NIR-LEDs is hindered predominantly by poor film quality and increased defect states, limiting potential industrial applications. Here, we modify the interface of perovskite films with phenethylammonium iodide (PEAI) to resolve these issues. The preheated MAPbI3 films are post-treated with PEAI solution, resulting in high film quality, full coverage, and dense MAPbI3 film. Incorporating lithium fluoride as an interfacial layer and CN-T2T as an electron transport layer, perovskite NIR-LEDs are demonstrated with a maximum external quantum efficiency (EQE) of 18.74%. The high EQE of the devices is investigated by electrical, optical, and physical analyses. The result shows the potential to develop efficient NIR perovskite LEDs for practical applications.