优化室温有机磷光分子体系的激发态动力学研究  

Enhancing room-temperature organic phosphorescence via excited-state dynamics study

作　　者：段宏星 吕学举[2] 王建 张红星 DUAN Hong-xing;LYU Xue-ju;WANG Jian;ZHANG Hong-xing(Jilin Provincial Experimental School,Changchun 130000,China;College of Chemistry,Jilin University,Changchun 130012,China)

机构地区：[1]吉林省实验中学,吉林长春130000 [2]吉林大学化学学院,吉林长春130012

出　　处：《分子科学学报》2023年第6期528-536,共9页Journal of Molecular Science

基　　金：国家自然科学基金资助项目(21873038)。

摘　　要：采用量子化学电子结构计算和非绝热激发态动力学手段,本文系统地研究了纯有机光致磷光体系1-(二苯并[b, d]呋喃-2-基)苯甲酮的振动分辨电子吸收光谱和激发态失活动力学.探讨了分子振动模式与隙间窜跃通道之间的关系,并针对性地进行了卤代修饰.研究发现在保持特征吸收峰不变的前提下,显著增强了低能区域特征峰的强度.引入Br和I重原子后,出现了明显的重原子效应,隙间窜跃速率激增高达百倍,从而显著提高了光感信号灵敏度.同时,修饰后的有机磷光发射颜色由浅绿色变为黄绿色,更利于人眼观察.这些结果为深入理解该体系的光物理化学性质和开发新型有机磷光探针提供了重要参考.In this study,we have undertaken a systematic investigation on the pure organic room-temperature phosphorescence system 1-(dibenz[b,d]furan-2-yl)benzaldehyde.The focus was on vibrationally-resolved electronic absorption spectra and trajectory surface-hopping dynamics that include intersystem crossing(ISC).To accomplish this,we employed(time-dependent)density functional theory(DFT)electronic structure calculations and nonadiabatic trajectory surface-hopping excited electronic state dynamics simulations with spin-orbit couplings on-the-fly.To gain insights into the internal molecular motions that facilitate ISC within the trajectories,we utilized time-resolved principal component analysis(PCA).By employing essential dynamics or principal component analysis,we were able to determine motion(s)that occurred primarily within the dynamics,regardless of whether they could be mapped into a normal mode or not.Based on our analysis,we discovered that the lowest triplet excited electronic state T_(1) starts to populate as early as 40 fs.The most significant motion mode in this state is primarily attributed to the movement of hydrogen atoms,the degenerate bending vibration of oxygen atoms,and the degenerate bending vibration of the benzene plane around the carbonyl.We also sought to identify the internal molecular motions that promote ISC.Based on the relationship between existing motion patterns and ISC channels,we designed molecular engineering improvements by introducing F,Cl,Br,or I for halogenation at specific sites.This approach was effective in maintaining the position of existing characteristic absorption peaks while significantly increasing the intensity of low-energy region characteristic absorption peaks after introducing heavy atoms such as Br or I.Furthermore,introducing Br or I heavy atoms can effectively accelerate ISC rate up to 100 times faster.Phosphorescent emission calculations revealed that after halogenation modification,the emission color changed from light green to yellow-green,which is more conducive

关 键 词：有机磷光 电子结构 激发态动力学 非绝热动力学 密度泛函理论 

分 类 号：O64[理学—物理化学]