Polymer‐Assisted Crystal Growth Regulation and Defect Passivation for Efficient Perovskite Light‐Emitting Diodes

Abstract Perovskite light‐emitting diodes (Pero‐LEDs) with external quantum efficiencies (EQEs) of over 20% have been achieved in the last several years. However, the reproducibility of such high‐efficiency Pero‐LEDs is still low. The perovskite film quality, especially for the non‐radiative defects, is crucial in determining the device performance. These defects may lie in bulk grains, grain boundaries, and interfaces of the as‐formed perovskite films. Here, a polymer infiltrative treatment method is developed to realize effective and universal defect passivation. Specifically, poly(vinylidene fluoride) (PVDF) polymer chains are blended into the perovskite films before they are fully crystallizing. This infiltrative treatment method can regulate crystallization and passivate defects through the chemical interactions of perovskite lattices and PVDF. As a result, high‐quality perovskite films with void‐free surfaces and few‐defect crystals are obtianed. The corresponding Pero‐LEDs show a maximum EQE of 22.29% and an average EQE of 20.44 ± 0.73% based on a statistical analysis of 50 devices, exhibiting excellent reproducibility. The work provides better insights into controlling crystal growth and defect passivation via polymer‐assisted methods for efficient Pero‐LEDs.