Efficient and Fast X-Ray Luminescence in Organic Phosphors Through High-Level Triplet-Singlet Reverse Intersystem Crossing  

作　　者：Yang Zhang Minghong Chen Xiaoze Wang Miao Lin Hongyu Wang Weihong Li Fuhai Chen Qing Liao Hongming Chen Qiushui Chen Meijin Lin Huanghao Yang 

机构地区：[1]Key Laboratory of Molecule Synthesis and Function Discovery,College of Chemistry,Fuzhou University,Fuzhou,Fujian 350116 [2]New Cornerstone Science Laboratory,MOE Key Laboratory for Analytical Science of Food Safety and Biology,College of Chemistry,Fuzhou University,Fuzhou,Fujian 350108 [3]College of Materials Science and Engineering,Fuzhou University,Fuzhou,Fujian 350116

出　　处：《CCS Chemistry》2024年第2期334-341,共8页中国化学会会刊（英文）

基　　金：supported by the National Key R&D Program of China(grant no.2020YFA0709900);the National Natural Science Foundation of China(grant nos.21971041,22201042,22027805,62134003,and 22104016);the Natural Science Foundation of Fujian Province(grant nos.2020J01447,2022J06008,and 2022J0121);the Research Foundation of Education Bureau of Fujian Province(grant no.JAT210001);the Fuzhou University Testing Fund of Precious Apparatus(grant no.2022T001).

摘　　要：Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbidden transitions in these materials often result in long-lived phosphorescence,which is undesirable for ultrafast X-ray detection and imaging.Here we demonstrate that the effect of hybridized local and charge-transfer(HLCT)excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence(RL)in response to X-ray irradiation.Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad(OMNI-PTZ 2)with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)on MNIπ-orbitals,and moderate donor–acceptor electron interactions.As a result,the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence(TADF)molecule MNI-PTZ 1.We further demonstrate the practical utility of the OMNI-PTZ 2(G)in high-performance X-ray detection and imaging,achieving an X-ray dose sensitivity of 97 nGy s−1 and an exceptional spatial resolution of 20 lp/mm.Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors.

关 键 词：organic scintillators X-ray imaging hybridized local and charge transfer excited state triplet-singlet reverse intersystem crossing high exciton utilization 

分 类 号：O62[理学—有机化学]