Two-Dimensional Perovskites with Alternating Diammonium and Methylammonium Cations in the Interlayer Space for Stable Light-Emitting Diodes

Metal halide perovskites constitute a promising area of research for application in light-emitting diodes (LEDs), given the successful demonstration of high external quantum efficiency (EQE) devices across the visible to the near-infrared window. Nevertheless, the ionic crystal structure, significantly impacted by internal defects and ionic migration, poses a challenge to the long-term stability of perovskite materials. This limitation stands as a pivotal hurdle impeding further commercialization of perovskite LEDs (PeLEDs). Two-dimensional (2D) perovskite-based materials strive to enhance the operational stability of PeLED devices by refining the crystal structure and passivating the film defects. To this end, we have successfully developed high-quality 2D perovskite thin films using 1,4-butanediammonium (BDA) and methylammonium as alternating cations in the interlayer space (ACI) for efficient LEDs with improved operational stability. Our best-performing device demonstrates an EQE of 4.3% at a high current density (J) of 130 mA/cm2 and remains above 3.3% for a J up to 510 mA/cm2, leading to a high radiance of 138 W/Sr·m2 when driven at 6 V. More importantly, this device shows impressive operational stability, retaining ∼80% of its initial performance operating at 25 mA/cm2 for 9 h. The utilization of ACI perovskites in PeLEDs demonstrates their potential for balancing both high stability and high efficiency.