Polymer-linked growth wafer-sized Ruddlesden-Popper perovskite single-crystal films.

Wafer-sized two-dimensional Ruddlesden-Popper perovskite single-crystal thin films (SCTFs) hold immense potential as alternatives for fabricating large-scale optoelectronic devices and are anticipated to achieve commercial application in technologies such as high-performance micro-PeLEDs and integrated panels for advanced displays of the future. However, wafer-sized growth of perovskite single-crystal films remains challenging, primarily attributed to the inherent difficulties in controlling the nucleation process and managing the anisotropic growth behavior. These factors lead to rapid nucleation rate and high nucleation density, which impede crystal wafer-sized growth. Herein, we design a polymer-linked assistance strategy to grow wafer-sized BA₂PbBr₄(BA=CH₃CH₂CH₂CH₂NH₃⁺) SCTFs. The coordination interaction between the polymers containing oxygen functional groups and lead ions enhances solution stability, reducing nucleation density and increasing nucleation size. Additionally, the polymers adsorb onto inorganic layers through coordination interaction, suppressing vertical crystal growth while promoting preferential lateral orientation. These mechanisms collectively facilitate the growth of wafer-sized, high-quality BA₂PbBr₄SCTFs. This strategy yields high-quality BA₂PbBr₄SCTFs with lateral dimension of 50.0 mm and thickness of 470.8 nm, representing a high aspect ratio more than 10⁵. The defects in BA₂PbBr₄SCTFs are suppressed by the coordination interaction between functional groups and lead ions. This work not only establishes a feasible strategy for wafer-sized growth of high-quality halide perovskite SCTFs, but also paves the way for their practical implementation in next-generation optoelectronic devices.