Volume‐Confined Fabrication of Large‐Scale Single‐Crystalline Molecular Ferroelectric Thin Films and Their Applications in 2D Materials

With outstanding advantages of chemical synthesis, structural diversity, and mechanical flexibility, molecular ferroelectrics have attracted increasing attention, demonstrating themselves as promising candidates for next‐generation wearable electronics and flexible devices in the film form. However, it remains a challenge to grow high‐quality thin films of molecular ferroelectrics. To address the above issue, a volume‐confined method is utilized to achieve ultrasmooth single‐crystal molecular ferroelectric thin films at the sub‐centimeter scale, with the thickness controlled in the range of 100–1000 nm. More importantly, the preparation method is applicable to most molecular ferroelectrics and has no dependency on substrates, showing excellent reproducibility and universality. To demonstrate the application potential, two‐dimensional (2D) transitional metal dichalcogenide semiconductor/molecular ferroelectric heterostructures are prepared and investigated by optical spectroscopic method, proving the possibility of integrating molecular ferroelectrics with 2D layered materials. These results may unlock the potential for preparing and developing high‐performance devices based on molecular ferroelectric thin films. Large‐scale single‐crystalline film of molecular ferroelectrics is achieved via a mild, simple, and substrate‐independent chemical process. The ultrasmooth surface and enduring ferroelectricity of the film enable the successful construction and optical control of heterostructures, enabling ferroelectric films for large‐scale flexible electronics.