Glutamine Induced High‐Quality Perovskite Film to Improve the Efficiency of NIR Perovskite Light‐Emitting Diodes

Abstract Formamidine lead iodide (FAPbI 3 ) is an important material for realizing high‐performance near‐infrared light‐emitting diodes (NIR‐LEDs). However, due to the uncontrollable growth of solution‐processed films which usually causes low coverage, and poor surface morphology, the development of FAPbI 3 ‐based NIR‐LEDs is hindered, restraining its potential industrial applications. In this work, by employing glutamine (Gln) in perovskite precursor, the quality of FAPbI 3 film is improved significantly. Due to the ameliorated solution process by the organic additive, the film coverage over the substrate is substantially enhanced. Meanwhile, the trap state of grain is largely reduced. Consequently, NIR perovskite LEDs are demonstrated with a maximum external quantum efficiency (EQE) of 15% with the emission peak at 795 nm, which is four times higher than the device with pristine perovskite film.