Abstract

Monolayer organiccrystals have attracted considerable attention due to their extraordinary optoelectronicproperties. Solution-self-assembly on water surface is an effective approach tofabricate monolayer organic crystals. However, due to the difficulties incontrolling the spreading of organic solution on water surface and weakintermolecular interaction between organic molecules, large-area growth ofmonolayer organic crystals remains a great challenge. Here, we report agraphene quantum dots (GQDs)-induced self-assembly method for centimeter-sizedgrowth of monolayer organic crystals on GQDs solution surface. The spreadingarea of organic solution can be readily controlled by tuning the pH value ofthe GQDs solution. Meanwhile, π-π stacking interaction between GQDs and organicmolecules can effectively reduce the nucleation energy of organic molecules andafford a cohesive force to bond the crystals, enabling large-area growth ofmonolayer organic crystals. Using 2,7-didecyl benzothienobenzothiopene (C₁₀-BTBT)as an example, centimeter-sized monolayer C₁₀-BTBT crystal withuniform molecular packing and crystal orientation is attained. Organicfield-effect transistors based on the monolayer C₁₀-BTBT crystalsexhibit a high mobility up to 2.6 cm² V^-1 s^-1,representing the highest mobility value for solution-assembled monolayerorganic crystals. Our work provides a feasible route for large-scale fabricationof monolayer organic crystals towards high-performance organic devices.