High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been pai...High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been paid to find ways to reduce the phosphors＇ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscyanophenyl-6-（12-phenylindole[2,3-a]carbazole-ll-yl）-1,3,5-triazine （BCPICT）, with thermally activated delayed fluorescent （TADF） properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m^2.展开更多
An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB) was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isoch...An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB) was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isochromen-1-one(MAC) to further improve the performance of thermally activated delayed fluorescence(TADF)emitters. With the additional phenyl in coumarin-contained plane, MAB possesses an extended distribution of the lowest unoccupied molecular orbitals(LUMO), and thus realizes reduced electron exchange between the frontier molecular orbitals and a stretched molecular dipole moment compared with MAC. MAB based organic light-emitting diode(OLED)exhibits a remarkable maximum external quantum efficiency(EQE) of 21.7%, which is much better than the maximum EQE of MAC-based OLED with a value of 12.8%. Our work proves that extending the distribution of LUMO is a simple but effective method to improve the efficiency of TADF emitter.展开更多
We fabricated organic light-emitting diodes （OLEDs） with the thermally activated delayed fluorescence （TADF） mate- rial of 4CzlPN, Which show better stability compared with the 4,4＇-Bis（carbazol-9-yl）biphenyl ...We fabricated organic light-emitting diodes （OLEDs） with the thermally activated delayed fluorescence （TADF） mate- rial of 4CzlPN, Which show better stability compared with the 4,4＇-Bis（carbazol-9-yl）biphenyl （CBP） based devices. The half lifetime of the device using 4CzlPN as host material has doubled, and a slower voltage rise compared with that of CBP-based devices has been achieved, which indicates the improvement of stability. We attribute the better sta- bility to the good film morphology and difficult crystallization property of 4CzlPN. Our results suggest that employing the 4CzlPN as host material can be a promising way of fabricating OLEDs with longer operation lifetime.展开更多
A series of new red fluorescent siloles consisting of a silole core and dimesitylboranyl substituent connected with a furan, thiophene, and selenophene bridges were synthesized and characterized. The optical propertie...A series of new red fluorescent siloles consisting of a silole core and dimesitylboranyl substituent connected with a furan, thiophene, and selenophene bridges were synthesized and characterized. The optical properties, electronic structures, and electroluminescence （EL） performances were investigated. The emission wavelengths were red-shifted from the siloles with furan, to those with thiophene, and then selenophene. The thiophene, and selenophene-containing siloles, （MesB）2DTTPS, and （MesB）zDSTPS, showed the typical aggregation-enhanced emission （AEE） feature, while furan-containing one, （MesB）2DFTPS, showed slight emission decrease as the aggregate formation. Theoretical calculations were carried out to explain the difference in the optical properties. Undoped OLEDs using these red siloles as light-emitting layers were fabricated. The device of （MesB）2DTTPS exhibited the best performance. It radiated red EL emission at 589 nm, and afforded good maximum luminance, current, power, and external quantum efficiency of 13300 cd m^-2, 4.3 cd A^-1, 2.9 lm W^-1, and 1.8%, respectively.展开更多
基金supported by the National Natural Science Foundation of China (51525304)the National Key Basic Research and Development Program of China (2015CB655002)
文摘High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been paid to find ways to reduce the phosphors＇ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscyanophenyl-6-（12-phenylindole[2,3-a]carbazole-ll-yl）-1,3,5-triazine （BCPICT）, with thermally activated delayed fluorescent （TADF） properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m^2.
基金supported by the National Natural Science Foundation of China (51773029, 51533005 and 51373190)the National Key Research & Development Program of China (2016YFB0401002)+1 种基金Collaborative Innovation Center of Suzhou Nano Science & Technology, the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the 111 Project and Qing Lan Project, China
文摘An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB) was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isochromen-1-one(MAC) to further improve the performance of thermally activated delayed fluorescence(TADF)emitters. With the additional phenyl in coumarin-contained plane, MAB possesses an extended distribution of the lowest unoccupied molecular orbitals(LUMO), and thus realizes reduced electron exchange between the frontier molecular orbitals and a stretched molecular dipole moment compared with MAC. MAB based organic light-emitting diode(OLED)exhibits a remarkable maximum external quantum efficiency(EQE) of 21.7%, which is much better than the maximum EQE of MAC-based OLED with a value of 12.8%. Our work proves that extending the distribution of LUMO is a simple but effective method to improve the efficiency of TADF emitter.
基金supported by the National High Technology Research and Development Program of China(No.2012AA011901)the National Basic Research Program of China(No.2012CB723406)+2 种基金the National Natural Science Foundation of China(No.51573036)the Fundamental Research Funds for the Central Universities of China(No.JD2016JGPY0007)the Industry-University-Research Cooperation Project of Aviation Industry Corporation of China(No.CXY2013HFGD20)
文摘We fabricated organic light-emitting diodes （OLEDs） with the thermally activated delayed fluorescence （TADF） mate- rial of 4CzlPN, Which show better stability compared with the 4,4＇-Bis（carbazol-9-yl）biphenyl （CBP） based devices. The half lifetime of the device using 4CzlPN as host material has doubled, and a slower voltage rise compared with that of CBP-based devices has been achieved, which indicates the improvement of stability. We attribute the better sta- bility to the good film morphology and difficult crystallization property of 4CzlPN. Our results suggest that employing the 4CzlPN as host material can be a promising way of fabricating OLEDs with longer operation lifetime.
基金supported by the National Natural Sci-ence Foundation of China (51273053)the National Basic Research Program of China (2015CB655004,2013CB834702)+3 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar (2014A 030306035)the Guangdong Innovative R esearch Team Program o f China (201101C0105067115)ITC-CN ERC14S01the Fundam ental Research Funds for the Central Univer- sities (2015PT020, 2015ZY013)
文摘A series of new red fluorescent siloles consisting of a silole core and dimesitylboranyl substituent connected with a furan, thiophene, and selenophene bridges were synthesized and characterized. The optical properties, electronic structures, and electroluminescence （EL） performances were investigated. The emission wavelengths were red-shifted from the siloles with furan, to those with thiophene, and then selenophene. The thiophene, and selenophene-containing siloles, （MesB）2DTTPS, and （MesB）zDSTPS, showed the typical aggregation-enhanced emission （AEE） feature, while furan-containing one, （MesB）2DFTPS, showed slight emission decrease as the aggregate formation. Theoretical calculations were carried out to explain the difference in the optical properties. Undoped OLEDs using these red siloles as light-emitting layers were fabricated. The device of （MesB）2DTTPS exhibited the best performance. It radiated red EL emission at 589 nm, and afforded good maximum luminance, current, power, and external quantum efficiency of 13300 cd m^-2, 4.3 cd A^-1, 2.9 lm W^-1, and 1.8%, respectively.
