Grain orientation management and recombination suppression for ultra-stable PeLEDs with record brightness

Three-dimensional (3D) polycrystalline perovskite is emerging as a promising candidate for high-brightness light-emitting applications. However, 3D perovskite light-emitting diodes (PeLEDs) are difficult to achieve high brightness, efficiency, and stability simultaneously, as they are limited by the trade-off between the advanced external quantum efficiency (EQE) and the inevitable roll-off. Here, we develop a 3D FAPbI₃ perovskite material system that enables high brightness, efficiency, and long device lifetime simultaneously, engineered by an alkyl-chain-length-dependent ammonium salt molecule modulation strategy. We elucidate the roles of alkylammonium salts on crystal orientation management, grain size control, non-radiative recombination suppression, and thus device performances. Consequently, we simultaneously obtain efficient, ultra-bright, and stable PeLEDs with a high EQE of 23.2%, a record radiance of 1,593 W sr⁻¹ m⁻² and a record lifetime of 227 h (at a high current density of 100 mA cm⁻²), representing the best performance for the DC-drive near-infrared (NIR) PeLEDs at high-brightness levels.