Hyperfluorescent organic light-emitting diodes(HF-OLEDs)approach has made it possible to achieve excellent device performance and color purity with low roll-off using noble-metal-free pure organic emitter.Despite sign...Hyperfluorescent organic light-emitting diodes(HF-OLEDs)approach has made it possible to achieve excellent device performance and color purity with low roll-off using noble-metal-free pure organic emitter.Despite significant progress,the performance of HF-OLEDs is still unsatisfactory due to the existence of a competitive dexter energy transfer(DET)pathway.In this contribution,two boron dipyrromethene(BODIPY)-based donor-acceptor emitters(BDP-C-Cz and BDP-N-Cz)with hybridized local and charge transfer characteristics(HLCT)are introduced in the HF-OLED to suppress the exciton loss by dexter mechanism,and a breakthrough performance with low-efficiency roll-off(0.3%)even at high brightness(1000 cd m^(-2))is achieved.It is demonstrated that the energy loss via the DET channel can be suppressed in HF-OLEDs utilizing the HLCT emitter,as the excitons from the dark triplet state of such emitters are funneled to its emissive singlet state following the hot-exciton mechanism.The developed HF-OLED device has realized a good maximum external quantum efficiency(EQE)of 19.25%at brightness of 1000 cd m^(-2)and maximum luminance over 60000 cd m^(-2),with an emission peak at 602 nm and Commission International de L'Eclairage(CIE)coordinates(0.57,0.41),which is among the best-achieved results in solution-processed HF-OLEDs.This work presents a viable methodology to suppress energy loss and achieve high performance in the HF-OLEDs.展开更多
Solution-processed fluorescent organic light-emitting diodes(OLEDs)are believed to be favorable for low-cost,large-area,and flexible displays but still suffer from the limited external quantum efficiency(EQE)below 5%....Solution-processed fluorescent organic light-emitting diodes(OLEDs)are believed to be favorable for low-cost,large-area,and flexible displays but still suffer from the limited external quantum efficiency(EQE)below 5%.Herein,we demonstrate the EQE breakthrough by introducing a donor–acceptor type thermally activated delayed fluorescence(TADF)polymer as the sensitizer for the typical green-emitting fluorescent dopants.Benefitting from their matched energy alignment,the unwanted trap-assisted recombination directly on fluorescent dopant is prevented to avoid the additional loss of triplet excitons.Indeed,triplet excitons are mainly formed on the polymeric TADF sensitizer via a Langevin recombination and then spin-flipped to singlet excitons due to the good upconversion capability.Followed by an efficient Förster energy transfer,both singlet and triplet excitons can be harvested by fluorescent dopants,leading to a promising solution-processed green hyperfluorescence with a record-high EQE of 21.2%(72.2cd/A,59.7lm/W)and Commission Internationale de L'Eclairage coordinates of(0.32,0.59).The results clearly highlight the great potential of solution-processed fluorescent OLEDs based on TADF polymers as the sensitizer.展开更多
基金supported by Guangdong Foundation of Basic and Applied Basic Research(2019B1515120023,2022B1515020041)National Natural Science Foundation of China(21975053,21975055,U2001222)for financial support
文摘Hyperfluorescent organic light-emitting diodes(HF-OLEDs)approach has made it possible to achieve excellent device performance and color purity with low roll-off using noble-metal-free pure organic emitter.Despite significant progress,the performance of HF-OLEDs is still unsatisfactory due to the existence of a competitive dexter energy transfer(DET)pathway.In this contribution,two boron dipyrromethene(BODIPY)-based donor-acceptor emitters(BDP-C-Cz and BDP-N-Cz)with hybridized local and charge transfer characteristics(HLCT)are introduced in the HF-OLED to suppress the exciton loss by dexter mechanism,and a breakthrough performance with low-efficiency roll-off(0.3%)even at high brightness(1000 cd m^(-2))is achieved.It is demonstrated that the energy loss via the DET channel can be suppressed in HF-OLEDs utilizing the HLCT emitter,as the excitons from the dark triplet state of such emitters are funneled to its emissive singlet state following the hot-exciton mechanism.The developed HF-OLED device has realized a good maximum external quantum efficiency(EQE)of 19.25%at brightness of 1000 cd m^(-2)and maximum luminance over 60000 cd m^(-2),with an emission peak at 602 nm and Commission International de L'Eclairage(CIE)coordinates(0.57,0.41),which is among the best-achieved results in solution-processed HF-OLEDs.This work presents a viable methodology to suppress energy loss and achieve high performance in the HF-OLEDs.
基金National Natural Science Foundation of China,Grant/Award Numbers:52273198,52173186,21961160720Yunnan Fundamental Research Projects,Grant/Award Numbers:202301BF070001-008,K264202230134+2 种基金The Yunling Scholar Project of“Yunnan Revitalization Talent Support Program”Natural Science Foundation of Jilin Province,Grant/Award Number:20230101358JCYouth Innovation Promotion Association。
文摘Solution-processed fluorescent organic light-emitting diodes(OLEDs)are believed to be favorable for low-cost,large-area,and flexible displays but still suffer from the limited external quantum efficiency(EQE)below 5%.Herein,we demonstrate the EQE breakthrough by introducing a donor–acceptor type thermally activated delayed fluorescence(TADF)polymer as the sensitizer for the typical green-emitting fluorescent dopants.Benefitting from their matched energy alignment,the unwanted trap-assisted recombination directly on fluorescent dopant is prevented to avoid the additional loss of triplet excitons.Indeed,triplet excitons are mainly formed on the polymeric TADF sensitizer via a Langevin recombination and then spin-flipped to singlet excitons due to the good upconversion capability.Followed by an efficient Förster energy transfer,both singlet and triplet excitons can be harvested by fluorescent dopants,leading to a promising solution-processed green hyperfluorescence with a record-high EQE of 21.2%(72.2cd/A,59.7lm/W)and Commission Internationale de L'Eclairage coordinates of(0.32,0.59).The results clearly highlight the great potential of solution-processed fluorescent OLEDs based on TADF polymers as the sensitizer.
