Chen Xuefeng, Wang Guangming, Piao Xixi, Zhang Kaka
State Key Laboratory of Organometallic Chemistry, Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China.
Chemistry. 2024 Mar 25;30(18):e202303834. doi: 10.1002/chem.202303834. Epub 2024 Feb 13.
Blue afterglow constitutes of one of the primary afterglow colors and can convert into other afterglow colors through energy transfer. The reported studies show the fabrication of blue afterglow emitters, but most of them are formed by room-temperature phosphorescence mechanism and require UVB lights as excitation source (these high-energy lights may damage organic systems). Here we report visible-light-excitable blue thermally activated delayed fluorescence type (TADF-type) afterglow materials via delicate control of excited states in difluoroboron β-diketonate (BFbdk) systems. Tiny change of the substituents in BFbdk system has been found to pose significant influence on excited state energy levels and consequently narrow the singlet-triplet splitting energy of the system. As a result, both forward and reverse intersystem crossing have been accelerated, leading to the emergence of BFbdk's TADF-type organic afterglow in rigid crystalline matrices. The resultant TADF-type afterglow materials exhibit emission lifetimes of several hundred milliseconds, photoluminescence quantum yield (PLQY) of 24.7 % and display temperature responsive property.
蓝色余辉是主要余辉颜色之一，可通过能量转移转化为其他余辉颜色。已报道的研究展示了蓝色余辉发光体的制备，但其中大多数是通过室温磷光机制形成的，并且需要紫外B光作为激发源（这些高能光可能会损害有机体系）。在此，我们通过对二氟硼β - 二酮（BFbdk）体系中的激发态进行精细调控，报道了可见光激发的蓝色热激活延迟荧光型（TADF型）余辉材料。已发现BFbdk体系中取代基的微小变化对激发态能级有显著影响，从而缩小了该体系的单重态 - 三重态分裂能。结果，正向和反向系间窜越均被加速，导致在刚性晶体基质中出现BFbdk的TADF型有机余辉。所得的TADF型余辉材料表现出几百毫秒的发射寿命、24.7%的光致发光量子产率（PLQY），并显示出温度响应特性。
