This paper reports the results on the nature of bond-order and net charge distributions predicted by Ab initio Hartree- Fock procedures for 1-amino-2-iminio-, 1-amino-3-iminio- and 1-amino-4-iminiotropylium cations th...This paper reports the results on the nature of bond-order and net charge distributions predicted by Ab initio Hartree- Fock procedures for 1-amino-2-iminio-, 1-amino-3-iminio- and 1-amino-4-iminiotropylium cations that incorporate, in order, the 1,7-, 1,3- and 1,5-diazapentadienium (vinamidinium) elements. There appears to be very little contribution from tropylium-type charge distribution, the positive charges residing largely in the nitrogen atoms. The partial bond fixations and charge distributions show interesting variation in the three isomers. The 1,3-isomer in which the 1,3-diazapentadienium element is preserved in the favoured zigzag conformation appears to be relatively the best stabilized. The six isomeric benzo-fused derivatives arising from the three amino-iminiotropylium cations show similar differences in patterns of behaviour. Interestingly, the isomer in which a zigzag 1,3-diazapentadienium element is conjugated with a styrene moiety receives the deepest stabilization. While showing that the element largely contributes to the relative stabilization among the systems studied, contribution from certain stereochemical destabilizing factors may not be insignificant.展开更多
Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged do...Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged donor–acceptor(D–A^(+))and D–A^(+)–D architectures are designed,innovatively based on the phosphonium cation electron acceptor.The symmetric D–A^(+)–D compound in doped film exhibits a high photoluminescence quantum yield of 0.91 and a short emission lifetime of 1.43 microseconds.Partially solution-processed organic lightemitting diodes based on these ionic TADF emitters achieve a maximum external quantum efficiency(EQE)of 18.3%and a peak luminance of 14,532 candelas per square meter(cd/m^(2))and show a small efficiency roll-off of 7.1%(EQE=17%)at a practical high luminance of 1000 cd/m^(2).These results demonstrate the high potential of phosphonium cations as promising electron acceptors to construct TADF emitters for high-performance electroluminescence devices.The current study opens up an appealing way for future exploitation of high-efficiency ionic TADF materials.展开更多
文摘This paper reports the results on the nature of bond-order and net charge distributions predicted by Ab initio Hartree- Fock procedures for 1-amino-2-iminio-, 1-amino-3-iminio- and 1-amino-4-iminiotropylium cations that incorporate, in order, the 1,7-, 1,3- and 1,5-diazapentadienium (vinamidinium) elements. There appears to be very little contribution from tropylium-type charge distribution, the positive charges residing largely in the nitrogen atoms. The partial bond fixations and charge distributions show interesting variation in the three isomers. The 1,3-isomer in which the 1,3-diazapentadienium element is preserved in the favoured zigzag conformation appears to be relatively the best stabilized. The six isomeric benzo-fused derivatives arising from the three amino-iminiotropylium cations show similar differences in patterns of behaviour. Interestingly, the isomer in which a zigzag 1,3-diazapentadienium element is conjugated with a styrene moiety receives the deepest stabilization. While showing that the element largely contributes to the relative stabilization among the systems studied, contribution from certain stereochemical destabilizing factors may not be insignificant.
基金This research was made possible as a result of a generous grant from the Key Research Program of Frontier Science,the Chinese Academy of Sciences(CAS)(grant no.QYZDJ-SSW-SLH033)the National Natural Science Foundation of China(grant no.52073286)+3 种基金the Natural Science Foundation of Fujian Province(grant no.2006L2005)the Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China(grant nos.2021ZR132 and 2021ZZ115)the Youth Innovation Foundation of Xiamen City(grant nos.3502Z20206082 and 3502Z20206083)the Major Research Project of Xiamen(grant no.3502Z20191015).
文摘Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged donor–acceptor(D–A^(+))and D–A^(+)–D architectures are designed,innovatively based on the phosphonium cation electron acceptor.The symmetric D–A^(+)–D compound in doped film exhibits a high photoluminescence quantum yield of 0.91 and a short emission lifetime of 1.43 microseconds.Partially solution-processed organic lightemitting diodes based on these ionic TADF emitters achieve a maximum external quantum efficiency(EQE)of 18.3%and a peak luminance of 14,532 candelas per square meter(cd/m^(2))and show a small efficiency roll-off of 7.1%(EQE=17%)at a practical high luminance of 1000 cd/m^(2).These results demonstrate the high potential of phosphonium cations as promising electron acceptors to construct TADF emitters for high-performance electroluminescence devices.The current study opens up an appealing way for future exploitation of high-efficiency ionic TADF materials.
