热活化延迟荧光分子取代基位置对发光性质影响的理论研究  

Theoretical study of substituent position effect on luminescence properties of the thermally activated delayed fluorescence molecules

作　　者：沈钰 张晴 曹泽星 SHEN Yu;ZHANG Qing;CAO Zexing(Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China;Huzhou Key Laboratory of Environmental Functional Materials and Pollution Control,School of Engineering,Huzhou University,Huzhou 313000,China)

机构地区：[1]厦门大学化学化工学院,福建省理论与计算化学重点实验室,福建厦门361005 [2]湖州师范学院工学院,湖州市环境功能材料与污染治理重点实验室,浙江湖州313000

出　　处：《厦门大学学报（自然科学版）》2023年第5期792-800,共9页Journal of Xiamen University：Natural Science

基　　金：国家自然科学基金(21873078,21933009)。

摘　　要：热活化延迟荧光(TADF)材料具有较高的激子利用率,在有机发光二极管(OLED)研究中备受关注.与蓝色和绿色TADF分子相比,红色TADF分子发光能隙窄,其激发态很容易以不发光的非辐射方式失活回到基态,因此,实验上很难获得发光效率较高的红色TADF材料.本文应用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法,研究了互为异构体的T-DA-2和C-DA-2分子的电子吸收光谱、延迟荧光性质及光物理过程机制.结果表明,T-DA-2和C-DA-2分子的电子吸收谱主要来自基态到较高能级激发态的电子跃迁,并且其荧光发射遵循反-Kasha规则.和C-DA-2分子相比,异构体T-DA-2分子因其更小的内转换速率和更有效的反系间窜越过程而具有更好的荧光和延时荧光特性,表现出显著的取代基位置效应.Thermally activated delayed fluorescence(TADF)materials have attracted considerable attention in the research field of organic light-emitting diode(OLED)due to their high exciton efficiency.In comparison with blue and green TADF molecules,red TADF molecules have a relatively narrow luminous energy gap,and their excited states are more prone to deactivate back to the ground state through the non-radiative decay.Therefore,it is difficult to obtain red TADF materials experimentally with high luminous efficiency.Herein,the density functional theory(DFT)and the time-dependent density functional theory(TD-DFT)were used to study electronic absorptions,delayed fluorescence properties,and photophysical processes of T-DA-2 and C-DA-2 isomers.The results show that the electronic absorptions of T-DA-2 and C-DA-2 molecules mainly arise from the electronic excitation from the ground state to high-lying excited states,and their fluorescence emissions follow the anti-Kasha rule.Compared to C-DA-2,the T-DA-2 isomer has better fluorescence and TADF characteristics due to smaller internal conversion rate and more efficient reverse intersystem crossing process,therefore showing significant substituent position effects.

关 键 词：热活化延迟荧光 激发态 取代基位置效应 含时密度泛函理论 量子力学/分子力学组合方法 

分 类 号：O644.17[理学—物理化学]