Growth of Fractal Crystalline C

The growth of organic semiconductor films with long-range ordered structures on device substrates is crucial for transistor performance and functionality. Wide-bandgap 2D materials, characterized by their atomic-level cleanness and inert surface properties, are considered ideal for growing high-quality organic films. However, there is still a lack of sufficient understanding regarding the growth behavior of organic molecules on 2D materials. Herein, a systematic study is presented on the crystal growth process of fullerene (C60) films from the nanoscale to the microscale and obtained its fractal growth mode and large-sized C60 layered crystalline thin films on mechanically exfoliated hexagonal boron nitride (h-BN) crystals. The balanced intermolecular interaction and molecule-substrate interaction, in conjunction with the high step edge barrier, are the primary factors contributing to the fractal but island growth of C60 films are revealed. Furthermore, based on these large-sized and highly crystalline polycrystalline thin films, high-electron-mobility phototransistors are fabricated and the resulting devices present high photoresponse performance with rapid photo-switching characteristics. This research offers a thorough investigation into the growth of highly crystalline organic thin films and advances our understanding of their optoelectronic properties.