Quasi-2D (Q2D) lead halide perovskites have emerged as promising materials for light-emitting diodes (LEDs) due to their tunable emission, sloweddown carrier diffusion, and improved stability. However, they are primarily fabricated through solution methods, which hinders its large-scale manufacture and practical applications. Physical-vapor-deposition (PVD) methods have well demonstrated the capability for reproducible, scalable, and layerby-layer fabrication of high quality organic/inorganic thin films. Herein, for the first time, the full-evaporation fabrication of organic-inorganic hybrid ((BA) 2 Cs n−1 Pb n Br 3n+1) Q2D-3D PeLEDs is demonstrated. The morphology and crystal phase of the perovskite are controlled from 3D to 2D by modulating material composition, annealing temperature, and film thicknesses. The confinement of carriers in 3D layers and the energy funnel effect are discovered and discussed. Importantly, a record high external quantum efficiency (EQE) of 5.3% based on evaporation method is achieved. Moreover, a centimeterscale PeLED (1.5 cm × 2 cm) is obtained. Furthermore, the T 50 lifetime of the device with an initial brightness of 100 cd m −2 is found to be 90 min with a thin layer PMMA passivation, which is among the longest for all PVD processed PeLEDs. Overall, this work casts a solid stepping stone towards the fabrication of high-performance PeLEDs on a large-scale.

Rapid progress in the domain of perovskite solar cells (PSCs) has boosted the power conversion efficiency (PCE) of such cells to 25.2%. However, the long‐term stability of a high‐performance PSCs is still the foremost concern that hinders its practical application. The interfaces are considered as the key part that determines the overall device performance and longevity. These interfaces include the intralayer grain boundaries (GBs) inside the perovskites, the interface between perovskites with electron/hole transport layer (ETL/HTL), and the interface of ETL/HTL with top/down contacts. To acquire a deep and detailed understanding of the impacts of interfacial properties, herein, a concise overview of recent interfacial engineering strategies with the aim of minimizing traps, promoting carrier extraction, and improving stability are summarized.