Beyond Conventional 2D Organic Semiconductors: Blade-Coated isoSiPc Thin Films with Tunable Crystalline Alignment for Organic Thin-Film Transistors

Abstract Solution-processable two-dimensional organic single crystals (2D OSCs) have emerged as a highly promising class of materials for organic thin-film transistors (OTFTs), offering grain-boundary-free, long-range ordered active layers with exceptional charge transport properties. However, the current majority of 2D OSCs rely on planar, high-aspect-ratio, π-conjugated systems decorated in-plane with peripheral alkyl chains. Herein, we prepare 2D OSC-based OTFTs via blade coating of a recent material with a unique topology, isoSiPc, which combines a silicon phthalocyanine core with siloxane solubilizing chains that pass through the center of the π-conjugated core. We demonstrate that blade speed provides precise control over film morphology, crystallite texture, and in-plane alignment. Remarkably, we observe a blade-speed-dependent reorientation of crystallites within the film, directly correlating with device performance. At the optimal blade speed, an average hole mobility of 0.22 cm2V–1s–1 is achieved. Furthermore, application of our recently developed iodine post treatment enhances the average mobility to 0.44 cm2V–1s–1, with a champion device reaching 0.70 cm2V–1s–1. These results establish isoSiPc as a promising and structurally distinct 2D OSC platform, expanding the molecular design space and demonstrating a viable route toward high-performance, solution-processed organic electronics.