Energy-efficient lighting sources are desired to provide another solution of carbon emission reduction.White organic light-emitting diodes are promising,because of theoretical internal quantum efficiencies for 100%ele...Energy-efficient lighting sources are desired to provide another solution of carbon emission reduction.White organic light-emitting diodes are promising,because of theoretical internal quantum efficiencies for 100%electric-to-light conversion.However,pure organic fluorescent materials still face a challenge in harvesting triplet excitons for radiation.Herein,we report a white fluorescent organic light-emitting diode having an external quantum efficiency of 30.7%and a power efficiency of 120.2 Im w^(-1).In the single emissive layers,we use blue thermally activated delayed fluorescent emitters to sensitize a yellow fluorescent emitter.Transient photoluminescence and electroluminescence analyses suggest that a blue thermally activated delayed fluorescent molecule with~100%reverse intersystem crossing efficiency and negligible triplet nonradiative rate constant completely converts triplet to singlet,suppressing triplet quenching by a yellow fluorescent emitter and ensuring 100%power conversion.展开更多
In this work, we designed and synthesized a novel spirocyclic compound functionalized spiro[fluorene-9,9'- xanthene] with carbazole group (2-carbazolyl-spiro[fluorene-9,9'-xanthene], SFX-Cz) via Friedel-Crafts and...In this work, we designed and synthesized a novel spirocyclic compound functionalized spiro[fluorene-9,9'- xanthene] with carbazole group (2-carbazolyl-spiro[fluorene-9,9'-xanthene], SFX-Cz) via Friedel-Crafts and Ullmann reaction, which is expected to own high thermal and morphological stability, and good carrier injection/ transporting properties due to the excellent hole transporting characteristics of carbazole and cruciform structure of spiro[fluorene-9,9'-xanthene]. The carbazole end-capped spiro[fluorene-9,9'-xanthene] SFX-Cz based PhOLEDs with Flrpic as phosphor emitter have been researched by varying dopant concentration, which exhibit the maximum EQEs of 8.9%, 7.4%, 9.1%, and 4.7% with the doping increasing from 10% to 50%. The higher performance PhOLEDs are independent on concentration variation from 10% to 30%, which suggests the bulky steric hindrance of SFX-Cz might be a potential canditate for high performance and inexpensive device with simplified process.展开更多
In this work, a novel molecule pyridinylfluorene/triphenylamine hybrid (TPyFTPA) with bulky steric hindrance effects has been synthesized successfully by substituting 9-(pyridine-2-yl)-fluoren-9-yl with triphenyla...In this work, a novel molecule pyridinylfluorene/triphenylamine hybrid (TPyFTPA) with bulky steric hindrance effects has been synthesized successfully by substituting 9-(pyridine-2-yl)-fluoren-9-yl with triphenylamine (TPA) via Friedel-Crafts reaction, which possesses good thermal stability and triplet energy (ET) of 420 ℃ with 5% weight loss and 2.86 eV, respectively. Moreover, the bulky steric hindrance material shows high stable morphology by heating to 200 ℃ without finding melting phenomena and crystallization that is demonstrated by differential scanning calorimetry (DSC) curve. The bulky pyridinylfluorene end-capped TPA has been used as host material for blue phosphorescent organic light-emitting diodes (PhOLEDs) with maximum external quantum efficiencies (EQEs) of 2.7%, 3.7%, and 3.5%, at the doping ratios of 10%, 30%, and 40%, respectively. The performances of TPyFTPA-based blue PhOLEDs own wide concentration ranging from 10% to 40%, which indicates the bulky TPyFTPA might be a potential candidate for inexpensive products with simplifying process for the applications in full-color display and solid state lighting.展开更多
In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties ...In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties of 3-Spiro,we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes(OLEDs).The device with 5% doping rate of 4 CzPNPh exhibits high external quantum efficiency(EQE) of 11%,which proves the potential of 3 D rigid structure emitters for OLEDs.展开更多
基金supported by the National Natural Science Foundation of China(92061205,62175060,51873056,61905070,and 22005088)the Young Innovative Team Supporting Projects of Heilongjiang Province,the National Science Fund for Excellent Young Scholars of Heilongjiang Province(YQ2020B006)+1 种基金the Postdoctoral Science Foundation of Heilongjiang Province(LBH-Q2116)the Fund for Distinguished Young Scholars of Heilongjiang University(JCL202001).
文摘Energy-efficient lighting sources are desired to provide another solution of carbon emission reduction.White organic light-emitting diodes are promising,because of theoretical internal quantum efficiencies for 100%electric-to-light conversion.However,pure organic fluorescent materials still face a challenge in harvesting triplet excitons for radiation.Herein,we report a white fluorescent organic light-emitting diode having an external quantum efficiency of 30.7%and a power efficiency of 120.2 Im w^(-1).In the single emissive layers,we use blue thermally activated delayed fluorescent emitters to sensitize a yellow fluorescent emitter.Transient photoluminescence and electroluminescence analyses suggest that a blue thermally activated delayed fluorescent molecule with~100%reverse intersystem crossing efficiency and negligible triplet nonradiative rate constant completely converts triplet to singlet,suppressing triplet quenching by a yellow fluorescent emitter and ensuring 100%power conversion.
文摘In this work, we designed and synthesized a novel spirocyclic compound functionalized spiro[fluorene-9,9'- xanthene] with carbazole group (2-carbazolyl-spiro[fluorene-9,9'-xanthene], SFX-Cz) via Friedel-Crafts and Ullmann reaction, which is expected to own high thermal and morphological stability, and good carrier injection/ transporting properties due to the excellent hole transporting characteristics of carbazole and cruciform structure of spiro[fluorene-9,9'-xanthene]. The carbazole end-capped spiro[fluorene-9,9'-xanthene] SFX-Cz based PhOLEDs with Flrpic as phosphor emitter have been researched by varying dopant concentration, which exhibit the maximum EQEs of 8.9%, 7.4%, 9.1%, and 4.7% with the doping increasing from 10% to 50%. The higher performance PhOLEDs are independent on concentration variation from 10% to 30%, which suggests the bulky steric hindrance of SFX-Cz might be a potential canditate for high performance and inexpensive device with simplified process.
文摘In this work, a novel molecule pyridinylfluorene/triphenylamine hybrid (TPyFTPA) with bulky steric hindrance effects has been synthesized successfully by substituting 9-(pyridine-2-yl)-fluoren-9-yl with triphenylamine (TPA) via Friedel-Crafts reaction, which possesses good thermal stability and triplet energy (ET) of 420 ℃ with 5% weight loss and 2.86 eV, respectively. Moreover, the bulky steric hindrance material shows high stable morphology by heating to 200 ℃ without finding melting phenomena and crystallization that is demonstrated by differential scanning calorimetry (DSC) curve. The bulky pyridinylfluorene end-capped TPA has been used as host material for blue phosphorescent organic light-emitting diodes (PhOLEDs) with maximum external quantum efficiencies (EQEs) of 2.7%, 3.7%, and 3.5%, at the doping ratios of 10%, 30%, and 40%, respectively. The performances of TPyFTPA-based blue PhOLEDs own wide concentration ranging from 10% to 40%, which indicates the bulky TPyFTPA might be a potential candidate for inexpensive products with simplifying process for the applications in full-color display and solid state lighting.
基金supported by the National Natural Science Foundation of China(No.51603055)the Natural Science Foundation of Heilongjiang Province(No.QC2017055)+1 种基金the China Postdoctoral Science Foundation(Nos.2016M601424,2017T100236)the Postdoctoral Foundation of Heilongjiang Province(Nos.LBH-Z16059,LBH-TZ10)。
文摘In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties of 3-Spiro,we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes(OLEDs).The device with 5% doping rate of 4 CzPNPh exhibits high external quantum efficiency(EQE) of 11%,which proves the potential of 3 D rigid structure emitters for OLEDs.