Efficient All-Inorganic Perovskite Light-Emitting Diodes Enabled by Simultaneous Growth Regulation and Defect Passivation

Metal-halide perovskites(MHPs) have attracted widespread attention as the next-generation luminescent materials due to their excellent emission characteristics, such as narrowband emission and tunable color. Compared with hybrid perovskites, all-inorganic perovskites have better thermal and chemical stability and can therefore provide the basis for high-performance light-emitting diodes (LEDs) with reasonable operating stability. However, due to the large grain size and relatively poor surface quality of inorganic perovskites, the radiation recombination efficiency is inefficient, leading to a reduced efficiency of LED devices. Here, we employed the additive 2-(9H-carbazol-9-yl)ethylphosphonic acid (2PACz) for a straightforward in situ reaction with three-dimensional (3-D) inorganic perovskite. 2PACz forms a covalent bond with under-coordinated lead atoms on the perovskite surface, effectively passivating surface defects and enhancing radiative recombination efficiency. Simultaneously, crystal growth was controlled to obtain high-quality inorganic perovskite thin films with a smooth surface and small grain size. This approach not only reduces trap density in the perovskite but also maintains excellent charge transport characteristics of 3-D perovskite. Consequently, we fabricated a perovskite light-emitting diode (PeLED) with a maximum brightness of 13 192 cd m $^{-\text{2}}$ , an external quantum efficiency (EQE) of up to 20.87%, and a half-lifetime of 479 h (at 100 cd m $^{-\text{2}}\text{)}$ .