Enhancing metal halide perovskite LED performance by minimizing ion migration through the design of a mixed 2D(RP+DJ)/3D active layer structure

Low dimensional perovskite has attracted much research attention in recent years due to its unique quantum well structure and enhanced stability. Although quasi-2D perovskites show great potential for light-emitting diodes due to their impressive performance, there are still challenges in achieving uniform n-phases and stable internal crystal structures in films. These inconsistencies can lead to reduced performance in LED devices. The fabrication of 2D/3D mixed structures has shown great potential for achieving efficient energy transfer from high band gap to low band gap and stable LEDs. In this work, the effect of 2D perovskite as an additive on the morphological, optical and optoelectronic properties of 3D MAPbBr3 perovskite was investigated. The 2D/3D mixed structure with 2D Ruddlesden-Popper (RP) phase and Dion-Jacobson (DJ) phase containing different concentrations of (OA)2PbBr4 and (BDA)PbBr4 perovskites was investigated. The effect of concentration on the crystal structure, quality and optical properties of perovskite films was also studied. Furthermore, we have mixed RP and DJ phases to preparing mixed phase 2D perovskite. The optimal concentrations of the three phases of 2D/3D mixed perovskite structures (x=20 %) were determined based on their PLQY and used as the active layer in the fabrication of LEDs. The mixture of 2D and 3D, led to a reduction in holes, defects and a subsequent increase in PLQY. The LEDs based on 2D(RP+DJ)/3D mixed perovskite, exhibited remarkable stability, with its luminance decreasing from 4639 cdm-2 to 3197 cdm-2 over a period of 15 days. This represents a 68 % retention of its initial brightness. The results show the significant reduction in hysteresis for the 2D/3D perovskite device with a mixed phase cation (RP+DJ). This indicates that the mixed cation approach is highly effective in suppressing ion migration within the perovskite layer.