Multiple Resonance Thermally Activated Delayed Fluorescence Sensitizers Enable Green-toUltraviolet Photon Upconversion:Application in Photochemical Transformations  

作　　者：Yaxiong Wei Ke Pan Xiaosong Cao Yuanming Li Xiaoguo Zhou Chuluo Yang 

机构地区：[1]Shenzhen Key Laboratory of Polymer Science and Technology,College of Materials Science and Engineering,Shenzhen University,Shenzhen 518060 [2]School of Physics and Electronic Information,Anhui Normal University,Wuhu,Anhui 241000 [3]Department of Chemical Physics,University of Science and Technology of China,Hefei,Anhui 230026

出　　处：《CCS Chemistry》2022年第12期3852-3863,共12页中国化学会会刊（英文）

基　　金：This research was made possible as a result of several generous grants from the National Natural Science Foundation of China(grant nos.51903159 and 91833304);the Shenzhen Science and Technology Program(grant nos.KQTD20170330110107046 and JCYJ20190808151209557).

摘　　要：Efficient visible-to-ultraviolet(UV)triplet-triplet annihilation upconversion(TTA-UC)with large anti-Stokes shift is highly promising for solar-powered and indoor applications.Nonetheless,the excitationwavelengthis confined to the blue region(<450 nm),mainly due to large energy loss during triplet sensitization,resulting in reduced photon utilization efficiency in practical scenarios.Herein,a series of multiple resonance thermally activated delayed fluorescence(MR-TADF)compounds are developed as purely organic sensitizers for the purpose of energy-loss reduction,which also feature intense absorbance in the visible region,high intersystem crossing efficiencies,and long triplet lifetimes.By pairing the MR-TADF sensitizers with appropriate acceptors,green-to-UV TTA-UC systems were realized with an anti-Stokes shift up to 1.05 eV,upconversion quantum yield up to 8.6%,and threshold excitation intensity as low as 9.2 mW cm^(−2) in solution.The TTA-UC pairs were applied as internal or external sources of UV photons to trigger energy-demanding photopolymerization and photoligation reactions even under excitation of low-power-density green light-emitting diode light,revealing the broad utility of thesemolecular upconverters.This work unlocks the huge potential of MR-TADF-type sensitizers in upconversion applications.

关 键 词：triplet-triplet annihilation upconversion visible-to-ultraviolet upconversion multiple resonance photochemical reactions 

分 类 号：O57[理学—粒子物理与原子核物理]