State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China.
Molecular Materials and Nanosystems, Institute for, Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
Chemistry. 2019 Jan 7;25(2):564-572. doi: 10.1002/chem.201804020. Epub 2018 Dec 10.
The packing mode of small-molecular semiconductors in thin films is an important factor that controls the performance of their optoelectronic devices. Designing and changing the packing mode by molecular engineering is challenging. Three structurally related diketopyrrolopyrrole (DPP)-based compounds were synthesized to study the effect of replacing C-C bonds by isoelectronic dipolar B←N bonds. By replacing one of the bridging C-C bonds on the peripheral fluorene units of the DPP molecules by a coordinative B←N bond and changing the B←N bond orientation, the optical absorption, fluorescence, and excited-state lifetime of the compounds can be tuned. The substitution alters the preferential aggregation of the molecules in the solid state from H-type (for C-C) to J-type (for B←N). Introducing B←N bonds thus provides a subtle way of controlling the packing mode. The photovoltaic properties of the compounds were evaluated in bulk heterojunctions with a fullerene acceptor and showed moderate performance as a consequence of suboptimal morphologies, bimolecular recombination, and triplet-state formation.
薄膜中小分子半导体的堆积模式是控制其光电设备性能的一个重要因素。通过分子工程设计和改变堆积模式具有挑战性。本文合成了三种结构相关的二酮吡咯并吡咯（DPP）基化合物，以研究用等电子偶极 B←N 键替代 C-C 键对堆积模式的影响。通过用配位 B←N 键替代 DPP 分子外围芴单元上的一个桥接 C-C 键，并改变 B←N 键的取向，可以调节化合物的光吸收、荧光和激发态寿命。取代改变了分子在固态中从 H 型（对于 C-C）到 J 型（对于 B←N）的优先聚集。因此，引入 B←N 键提供了一种控制堆积模式的微妙方法。用富勒烯受体评估了这些化合物在本体异质结中的光伏性能，由于形貌不佳、双分子复合和三重态形成，导致性能中等。
