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

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.