Wang Jinwen, Wu Xiaofeng, Pan Jing, Feng Tanglue, Wu Di, Zhang Xiujuan, Yang Bai, Zhang Xiaohong, Jie Jiansheng
Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China.
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, Jilin, 130012, P. R. China.
Adv Mater. 2020 Sep;32(38):e2003315. doi: 10.1002/adma.202003315. Epub 2020 Aug 16.
Monolayer organic crystals have attracted considerable attention due to their extraordinary optoelectronic properties. Solution self-assembly on the surface of water is an effective approach to fabricate monolayer organic crystals. However, due to the difficulties in controlling the spreading of organic solution on the water surface and the weak intermolecular interaction between the organic molecules, large-area growth of monolayer organic crystals remains a great challenge. Here, a graphene quantum dots (GQDs)-induced self-assembly method for centimeter-sized growth of monolayer organic crystals on a GQDs solution surface is reported. The spreading area of the organic solution can be readily controlled by tuning the pH value of the GQDs solution. Meanwhile, the π-π stacking interaction between the GQDs and the organic molecules can effectively reduce the nucleation energy of the organic molecules and afford a cohesive force to bond the crystals, enabling large-area growth of monolayer organic crystals. Using 2,7-didecyl benzothienobenzothiopene (C-BTBT) as an examples, centimeter-sized monolayer C-BTBT crystal with uniform molecular packing and crystal orientation is attained. Organic field-effect transistors based on the monolayer C-BTBT crystals exhibit a high mobility up to 2.6 cm V s, representing the highest mobility value for solution-assembled monolayer organic crystals. This work provides a feasible route for large-scale fabrication of monolayer organic crystals toward high-performance organic devices.
单层有机晶体因其优异的光电特性而备受关注。在水面上进行溶液自组装是制备单层有机晶体的一种有效方法。然而，由于难以控制有机溶液在水面上的铺展以及有机分子间较弱的分子间相互作用，单层有机晶体的大面积生长仍然是一个巨大的挑战。在此，报道了一种石墨烯量子点（GQDs）诱导的自组装方法，用于在GQDs溶液表面实现厘米级尺寸的单层有机晶体生长。通过调节GQDs溶液的pH值，可以轻松控制有机溶液的铺展面积。同时，GQDs与有机分子之间的π-π堆积相互作用能够有效降低有机分子的成核能量，并提供一种内聚力来粘结晶体，从而实现单层有机晶体的大面积生长。以2,7-二癸基苯并噻吩并苯并噻吩（C-BTBT）为例，获得了具有均匀分子排列和晶体取向的厘米级单层C-BTBT晶体。基于单层C-BTBT晶体的有机场效应晶体管展现出高达2.6 cm² V⁻¹ s⁻¹的高迁移率，这代表了溶液组装单层有机晶体的最高迁移率值。这项工作为大规模制备用于高性能有机器件的单层有机晶体提供了一条可行的途径。
