Purely organic luminescent materials with ultralong room temperature phosphorescence by photo-activation have attracted great interest owing to their advantages of clean, safe, easy-to-use and control. Herein, we designed and synthesized a series of ultralong room temperature phosphorescence carbazole derivatives using flexible alkyl with different lengths to adjust the distance between two conjugated carbazole groups. Only, CzC3Cz crystal has the dynamic ultralong organic phosphorescence with increasing the excitation time of 365 nm UV light. By prolonging the UV excitation time (from 5 s to 3 min), room temperature phosphorescence intensity was improved about 10 times and phosphorescence lifetime increased from 48 ms to 898 ms. Additionally, it exhibited favorable stability and repeatability. Comparing the single crystal structure before and after photo-activation, intermolecular interaction of pi center dot center dot center dot pi and C-H center dot center dot center dot pi bond strengthens indicating that metastable state appears after long-time excitation of UV light. Considering the photo-activation characteristic, encryption pattern was prepared using the sifted compounds with similar phosphorescence performance for the application of anti-counterfeiting.

A purely organic D-pi-A-pi-D type emitter showing thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) was designed and synthesized by utilizing the benzophenone as an acceptor and the N-phenyl-2-napthylamine as a donor moiety. It exhibits considerable TADF character in doped PMMA film and room temperature phosphorescence with a long lifetime of 74 ms at 466 nm in solid state. The devices with the configuration of ITO/Mo2O3 (4 nm)/mCP (30 nm)/mCP: x wt% NP2BP/TmTyPB (60 nm)/LiF (1.5 nm)/Al (100 nm) were prepared by vacuum evaporation to explore their electroluminescent performance. Interestingly, the non-doped device has obtained near-white emission with a fluorescence emission peak at 475 nm and a phosphorescence emission peak at 563 nm having the CIE coordinate of (0.23, 0.32) and the maximum external quantum efficiency of 1.09%. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

开发新型有机红光材料对于制备高性能红光有机电致发光器件具有重要的研究意义.本文采用SU-ZUKI偶联反应,以芴酮为受体(A)、3,4,5-三甲氧基苯为给体(D)合成了新型D-π-A-π-D结构的有机红光材料(3MeFO).通过1 H NMR谱、13 C NMR谱和X单晶衍射确认了分子结构,该化合物展示了较强的电荷转移作用和良好的共轭结构,其晶体的发射峰达到620 nm.从单晶结构中看出甲氧基的引入有利于在分子间形成大量的氢键,有效地增强了分子间的相互作用.同时,该材料表现出良好的热稳定性能和电化学性能,使得其在OLED中展示了良好的电致发光性能.