2D organic semiconductor crystals are considered as ideal material systems for realizing high-performance organic field-effect transistors due to their ultrathin properties and long-range ordered molecular packing structures. However, the "coffee ring" effect caused by evaporative convection near the contact line seriously hinders the large-area preparation of 2D organic crystals by solution method. To this end, the research group of Prof. Jiansheng Jie of Soochow University has developed a new strategy for the growth of large-area two-dimensional organic crystals by effectively suppressing the "coffee ring" effect by using a blend solution of organic semiconductors and polymers. Both experiments and theoretical simulations have proved that the addition of high-viscosity polymers can significantly reduce the mass transfer rate of evaporative convection to the contact line, ensuring that organic molecules are uniformly deposited on the entire substrate, which is beneficial to inhibit the out-of-plane direction of organic molecules. crystallization, thereby greatly promoting in-plane two-dimensional crystallization. Using this method, wafer-scale thin films composed of few-layer 2,7-didecylbenzothienobenzothiophene two-dimensional molecular crystals were successfully realized. In addition, the organic field-effect transistor based on the 2D crystal exhibits excellent electrical properties, with a hole mobility of up to 12.6 cm2•V−1•s−1, and the average mobility of 36 devices is 8.2 cm2•V−1•s−1. This work provides a new idea for realizing large-area ultrathin 2D organic semiconductor crystals.

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