Xu Zhenzhen, Zhang Zhiwei, Jin Xue, Liao Qing, Fu Hongbing
Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing, 100048, People's Republic of China.
Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Sciences, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, People's Republic of China.
Chem Asian J. 2017 Dec 5;12(23):2985-2990. doi: 10.1002/asia.201701207. Epub 2017 Nov 2.
Color tuning of organic solid-state luminescent materials remains difficult and time-consuming through conventional chemical synthesis. Herein, we reported highly efficient polymorph-dependent green (P1), yellow (P2), and red (P3) emissions of organic crystals made by the same molecular building blocks of 4-(2-{4-[2-(4-diphenylamino-phenyl)-vinyl]-phenyl}-vinyl)-benzonitrile (DOPVB). Single-crystal X-ray diffraction (XRD) and spectroscopic data reveal that all three polymorphs follow the herringbone packing motif in H-type aggregations. On the one hand, from P1, P2 to P3, the reduced pitch translation along π stacks increases the intermolecular interactions between adjacent molecules, therefore leading to gradually red-shifted emissions from 540, 570 to 614 nm. On the other hand, the edge-to-face arrangement and large roll translations avoid strong π-π overlap, making P1, P2 and P3 highly emissive with record-high solid-state fluorescence quantum yields of 0.60, 0.98, and 0.68, respectively. Furthermore, the optically allowed 0-1 transitions of herringbone H-aggregates of P1, P2 and P3 naturally provide a four-level scheme, enabling green and yellow amplified spontaneous emissions (ASE) with very low thresholds.
通过传统化学合成方法对有机固态发光材料进行颜色调谐仍然困难且耗时。在此，我们报道了由4-(2-{4-[2-(4-二苯胺基苯基)-乙烯基]-苯基}-乙烯基)-苯甲腈（DOPVB）的相同分子结构单元制成的有机晶体呈现出高效的多晶型依赖性绿色（P1）、黄色（P2）和红色（P3）发射。单晶X射线衍射（XRD）和光谱数据表明，所有三种多晶型在H型聚集体中均遵循人字形堆积模式。一方面，从P1、P2到P3，沿π堆积方向的螺距平移减小，增加了相邻分子间的分子间相互作用，因此导致发射峰从540、570 nm逐渐红移至614 nm。另一方面，面对面排列和大的滚动平移避免了强烈的π-π重叠，使得P1、P2和P3具有高发射率，其固态荧光量子产率分别达到创纪录的0.60、0.98和0.68。此外，P1、P2和P3的人字形H聚集体的光学允许的0-1跃迁自然地提供了一个四能级方案，实现了绿色和黄色的放大自发发射（ASE），且阈值非常低。
