Low Roll-Off and High Stable Electroluminescence in Three-Dimensional FAPbI3 Perovskites with Bifunctional-Molecule Additives.

Three-dimensional (3D) perovskites have been demonstrated as an effective strategy to achieve efficient light-emitting diodes (LEDs) at high brightness. However, most 3D perovskite LEDs still suffer from serious efficiency roll-off. Here, using FAPbI3 as a model system, we find that the main reason for efficiency droop and degradation in 3D perovskite LEDs is defects and the ion migration under electrical stress. By introducing bifunctional-molecule 3-chlorobenzylamine additive into the perovskite precursor solution, the detrimental effects can be significantly suppressed through the growth of high crystalline perovskites and defect passivation. This approach leads to bright near-infrared perovskite LEDs with a peak external quantum efficiency of 16.6%, which sustains 80% of its peak value at a high current density of 460 mA cm-2, corresponding to a high brightness of 300 W sr-1 m-2. Moreover, the device exhibits a record half-lifetime of 49 h under a constant current density of 100 mA cm-2.