Two-dimensional melt growth of large-scale, single-crystalline hybrid organic-inorganic perovskite films

Melt growth is a process for creating large, bulk single crystals by solidifying a molten material. It combines elements of the Czochralski method, which creates a molten phase, and the Bridgman method, which controls the temperature gradient. Here, we apply two-dimensional (2D) melt growth to synthesize large-scale, single-crystal hybrid organic-inorganic perovskites (HOIPs), enabling substrate-agnostic crystallization with precise thickness control. Our method involves a vapor-liquid-solid process, where the reaction between the pre-deposited inorganic Na x PbBr y seeding layer and the organic precursor flux produces the 2D molten phase of HOIPs. This molten phase spreads into a 2D liquid film and allows uniform, large-scale crystallization of ultrathin HOIPs in a substrate-agnostic manner, bypassing requirements for lattice matching. Using this approach, we successfully grow 2D ( n = 1) and quasi-2D ( n > 1) ferroelectric HOIP films on SiO 2 /Si wafers at a low thermal budget, enabling direct large-scale device fabrication. Statistical analysis of devices demonstrates reliable ferroelectric switching and uniform electronic performance across the film. Our method holds great potential for other types of HOIPs and heterostructures, paving the way for applications in large-scale on-chip devices.