Growing two-dimensional single crystals of organic semiconductors on liquid surfaces

Two-dimensional (2D) organic semiconducting single crystals (OSSCs) combine the advantages of OSSCs and 2D molecular materials, and currently, are an important and hot research topic in the field of organic optoelectronics and 2D materials. Growth of large-sized 2D OSSCs with controlled thickness is highly important for fundamental research and practical application, which is still a challenging task. Liquid surfaces can provide ideal platforms for growth of large-scale and layer-controlled 2D OSSCs because their surfaces are molecularly flat and free-defect, the “coffee-ring” effect can be effectively suppressed on liquid surfaces, and the improved spread area of organic semiconductor solutions on liquid surfaces. This perspective concentrates on recent advances in the growth of large-area and layer-controlled 2D OSSCs on liquid surfaces; the optoelectronic applications based on 2D OSSCs, as well as the challenges and outlooks in the field, are also discussed.