Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color...Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color pixels,the fluorescent color conversion layer inevitably includes green and red pixels.To fabricate such sort of display kits,inkjet printing is a promising way to position the color conversion layers.In this review article,the progress of AR/VR technologies is first reviewed,and in succession,the state of the art of inkjet printing,as well as two key issues-the optimization of ink and the reduction of coffee-ring effects,are introduced.Finally,some potential problems associated with the color converting layer are highlighted.展开更多
Theoretically,blue phosphorescent materials are capable of achieving 100%internal quantum effi-ciency.Nevertheless,the mutual constraints among efficiency,color purity,and stability remain one of the key bottlenecks i...Theoretically,blue phosphorescent materials are capable of achieving 100%internal quantum effi-ciency.Nevertheless,the mutual constraints among efficiency,color purity,and stability remain one of the key bottlenecks in the industrialization of organic light-emitting diodes(OLEDs).In addition,the design and application of host materials also exert a significant impact on the overall performance of blue light-emitting de-vices.To address this issue,this study constructs a series of host materials with high triplet energy levels by designing different connection modes,based on 9-phenylcarbazole and benzimidazole units.Through a combi-nation of theoretical and experimental approaches,the correlation between the chemical structure and perfor-mance has been unraveled.It is found that the designed and synthesized blue phosphorescent bipolar host ma-terials based on different biphenyl linking sites,i.e.,9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-bi-phenyl]-3-yl)-9H-carbazole(mCzmBI),9-(2'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-3-yl)-9H-carbazole(mCzoBI)and 9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-2-yl)-9H-carbazole(oCzmBI).The three compounds have a similar triplet energy level of 2.70 eV,accompanied with the glass transition temperatures of 92℃,103℃,and 93℃respectively.mCzmBI,mCzoBI and oCzmBI are regioiso-mers,but differ in the linking sites of carbazole and benzimidazole on the biphenyl linker.This difference in linking positions enables effective regulation of the host materials’properties.Constructed with the blue phos-phorescent material bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium(Ⅲ)(FIrpic)as the vip,the influence of the three hosts on device performance is clarified.Overall,the device using mCzmBI,a host linked by biphenyl at double meta-positions,achieved a maximum current efficiency of 24.9 cd·A^(-1)and a max-imum external quantum efficiency exceeding 12.8%,it also demonstrates low efficiency roll-off under highbrightness conditions.This work offers an effective strategy to the development of high-efficiency blue phospho-rescent hosts.展开更多
Two tetrasubstituted carbazole derivatives TBICz and TOXDCz have been designed and synthesized,which possess the twist skeletons and exhibit excellent thermal and morphological stabilities.Utilizing these novel compou...Two tetrasubstituted carbazole derivatives TBICz and TOXDCz have been designed and synthesized,which possess the twist skeletons and exhibit excellent thermal and morphological stabilities.Utilizing these novel compounds as host material,high efficiency solution-processed green phosphorescent organic light-emitting diodes(PhOLEDs)have been achieved.The high triplet energies of TBICz and TOXDCz ensure efficient energy transfer from the host to the phosphor and triplet exciton confinement on the phosphor.Solution-processable green phospho⁃rescent devices employing Ir(ppy)3 as vip and the two tetrasubstituted carbazole derivatives as hosts exhibit high ef⁃ficiencies.The best EL performance is achieved for the TBICz-based device,with a maximum current efficiency of 27.3 cd/A,a maximum power efficiency of 15.9 lm/W,and a maximum external quantum efficiency of 7.8%,which provides more host material options for solution-processed OLEDs.展开更多
基金supported by the National Natural Science Foundation of China (11904302)the Fundamental Research Funds for the Central Universities (Grant No.20720190005)+1 种基金the Major Science and Technology Project of Xiamen in China (3502Z20191015)Hong Kong University of Science and Technology-Foshan Joint Research Program (FSUST19-FYTRI11)
文摘Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color pixels,the fluorescent color conversion layer inevitably includes green and red pixels.To fabricate such sort of display kits,inkjet printing is a promising way to position the color conversion layers.In this review article,the progress of AR/VR technologies is first reviewed,and in succession,the state of the art of inkjet printing,as well as two key issues-the optimization of ink and the reduction of coffee-ring effects,are introduced.Finally,some potential problems associated with the color converting layer are highlighted.
文摘Theoretically,blue phosphorescent materials are capable of achieving 100%internal quantum effi-ciency.Nevertheless,the mutual constraints among efficiency,color purity,and stability remain one of the key bottlenecks in the industrialization of organic light-emitting diodes(OLEDs).In addition,the design and application of host materials also exert a significant impact on the overall performance of blue light-emitting de-vices.To address this issue,this study constructs a series of host materials with high triplet energy levels by designing different connection modes,based on 9-phenylcarbazole and benzimidazole units.Through a combi-nation of theoretical and experimental approaches,the correlation between the chemical structure and perfor-mance has been unraveled.It is found that the designed and synthesized blue phosphorescent bipolar host ma-terials based on different biphenyl linking sites,i.e.,9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-bi-phenyl]-3-yl)-9H-carbazole(mCzmBI),9-(2'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-3-yl)-9H-carbazole(mCzoBI)and 9-(3'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-2-yl)-9H-carbazole(oCzmBI).The three compounds have a similar triplet energy level of 2.70 eV,accompanied with the glass transition temperatures of 92℃,103℃,and 93℃respectively.mCzmBI,mCzoBI and oCzmBI are regioiso-mers,but differ in the linking sites of carbazole and benzimidazole on the biphenyl linker.This difference in linking positions enables effective regulation of the host materials’properties.Constructed with the blue phos-phorescent material bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium(Ⅲ)(FIrpic)as the vip,the influence of the three hosts on device performance is clarified.Overall,the device using mCzmBI,a host linked by biphenyl at double meta-positions,achieved a maximum current efficiency of 24.9 cd·A^(-1)and a max-imum external quantum efficiency exceeding 12.8%,it also demonstrates low efficiency roll-off under highbrightness conditions.This work offers an effective strategy to the development of high-efficiency blue phospho-rescent hosts.
文摘Two tetrasubstituted carbazole derivatives TBICz and TOXDCz have been designed and synthesized,which possess the twist skeletons and exhibit excellent thermal and morphological stabilities.Utilizing these novel compounds as host material,high efficiency solution-processed green phosphorescent organic light-emitting diodes(PhOLEDs)have been achieved.The high triplet energies of TBICz and TOXDCz ensure efficient energy transfer from the host to the phosphor and triplet exciton confinement on the phosphor.Solution-processable green phospho⁃rescent devices employing Ir(ppy)3 as vip and the two tetrasubstituted carbazole derivatives as hosts exhibit high ef⁃ficiencies.The best EL performance is achieved for the TBICz-based device,with a maximum current efficiency of 27.3 cd/A,a maximum power efficiency of 15.9 lm/W,and a maximum external quantum efficiency of 7.8%,which provides more host material options for solution-processed OLEDs.
