The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. Th...The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. The research on the change trend of CCT and the law of extending the change range of CCT will help to further improve the performance of this kind of device. The present work fabricated a series of CT-WOLED devices with a simple structure, which are all composed of two ultra-thin phosphor layers (PO-01 and Flrpic) and a spacer interlayer. The yellow interface exciplex (TCTA/PO-T2T) formed between the spacer layer (PO-T2T) and transmission material (TCTA) in EML will decrease the CCT value at low voltage. The relationship between the energy transfer in EML and CCT change trend is investigated by adjusting the interface exciplexes and the thickness of the interlayer or the phosphor layer in devices A, B and C, respectively. The results demonstrate that a simple OLED device with an interlayer inserted between two ultra-thin phosphor layers can achieve a wider CCT span from 3359 K to 6451 K at voltage increases from 2.75 V to 8.25 V. .展开更多
The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, w...The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, with the increase of voltage, the movement of the recombination zone (RZ) is inevitable because the perfect bipolar host material is difficult to obtain, which will redistribute the energy in the light emitting layer (EML) and affect the stability of the spectrum. We fabricate a series of ternary hybrid WOLEDs with a simple structure by inserting ultra-thin PO-T2T into the blue exciplex (TCTA:TPBi) to form the green interface exciplex. Without considering the movement of RZ, device B2 realizes the dynamic balance energy distribution in EML and stable spectrum by controlling two processes of the Dexter energy transfer and exciton capture. By modifying the doping ratio of the host material, we also find that the broadened RZ is helpful to further improve the spectral stability of the device. When the voltage changes from 3 V to 7 V, the change range of color coordinates is only (0.026, 0.025).展开更多
White organic light-emitting diodes(WOLEDs)have several desirable features,but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device struc...White organic light-emitting diodes(WOLEDs)have several desirable features,but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures.Herein,we investigate a standard blue emitting hole transporting material(HTM)N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine(NPB)and its exciplex emission upon combining with a suitable electron transporting material(ETM),3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole(TAZ).Blue and yellow OLEDs with simple device structures are developed by using a blend layer,NPB:TAZ,as a blue emitter as well as a host for yellow phosphorescent dopant iridium(III)bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate(PO-01).Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units.The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer(CGL).Judicious choice of the spacer prevents exciton difusion from the blue emitter unit,yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation.This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission.The overall white light emission properties are enhanced,achieving CIE coordinates(0.36,0.39)and color temperature(4643 K)similar to daylight.Employing intermolecular exciplex emission in OLEDs simplifes the device architecture via its dual functionality as a host and as an emitter.展开更多
Metal-free room-temperature phosphorescence(RTP)materials have the characteristics of large Stokes shift,long lifetime,and triplet state transition.They exhibit application potential in various fields,such as bioimagi...Metal-free room-temperature phosphorescence(RTP)materials have the characteristics of large Stokes shift,long lifetime,and triplet state transition.They exhibit application potential in various fields,such as bioimaging,computer display,sensor,and anticounterfeiting and have drawn much research interest.Recent work showed that manipulating intermolecular interactions(e.g.,crystallization,polymerization,and rigid matrix)and host-guest assembly to restrain nonradiative transitions and isolate phosphor from oxygen as much as possible is a feasible way to obtain various types of efficient RTP materials.In some cases,intermolecular interactions also facilitated RTP emission by regulating the triplet state.On the other hand,heavy atoms(Br,I,etc.),heteroatoms(N,O,S,etc.),or carbonyls were introduced to the molecular skeleton through molecular engineering to enhance intersystem crossing,which is important for populating the triplet exciton.By comprehensively using the aforesaid strategies,great progress has been made for RTP materials.In this mini-review,we summarized recent advances in organic RTP materials based on manipulating intermolecular interactions.Typical host-guest assembly,hydrogen-bond assembly,energy transfer process,and exciplex emission system-based RTP materials were well illustrated.In summary,the current challenges and prospects for development in this field were presented.展开更多
Comprehensive Summary Duration-tunable afterglow materials have garnered considerable attention in various applications.Herein,carbon dots(CDs)-based long persistent luminescence(LPL)composites with a tunable duration...Comprehensive Summary Duration-tunable afterglow materials have garnered considerable attention in various applications.Herein,carbon dots(CDs)-based long persistent luminescence(LPL)composites with a tunable duration in an ultrawide range of seconds-to-hours levels were designed and prepared for the first time.In contrast to the established CD-based afterglow materials,we reported that CD-based composites exhibit LPL in the form of exciplexes and long-lived charge-separated states,enabling the LPL to be prolonged from several seconds to over one hour,exceeding the typical regulation range(limited to 1 min).Further studies revealed that the relationship between the excited and charge-transfer states of CDs plays a pivotal role in activating the LPL and regulating its duration.Furthermore,these composites exhibited high photoluminescence(PL)quantum yields of up to 60.63%,and their LPL was robust under ambient conditions,even in aqueous media.Their robust and superior LPL performance endows these composites with a strong competitive advantage in dynamic display systems,such as tags for time-resolved data encryption and displays of the remaining time of takeaways.This study offers an approach to preparing CDs-based LPL composites with tunable durations and may provide new insights for the development of rare-earth-free LPL materials.展开更多
High efficient yellow organic light emitting diodes （OLEDs） based on exciplex were reported. The exciplex was formed by 4, 4＇, 4″-tris β-methylphenyl （phenyi） amino]-triphenylamine （m-MTDATA） and 4, 7- diphen...High efficient yellow organic light emitting diodes （OLEDs） based on exciplex were reported. The exciplex was formed by 4, 4＇, 4″-tris β-methylphenyl （phenyi） amino]-triphenylamine （m-MTDATA） and 4, 7- diphenyl-1, 10-phenanthroline （BPhen）. The resulting yellow OLEDs exhibited an external quantum efficiency of over 7%, which is attributed to the effective energy back transfer from exciplex triplet state to exciplex singlet state. The maximum power efficiency of 25 lm/W was achieved. Doping a yellow phosphor Ir（bt）2（acac） into m-MTDATA： BPhen blend, a high efficiency device was achieved with a turn-on voltage of 2.1 V, maximum power efficiency and external quantum efficiency of 86.1 lm/W and 20.7%, respectively.展开更多
4,7-Bisphenyl-1,10-phenanthroline(BPhen)is a promising electron transport material(ETM)and has been widely used in organic light-emitting diodes(OLEDs)because of the large electron mobility and easy fabrication proces...4,7-Bisphenyl-1,10-phenanthroline(BPhen)is a promising electron transport material(ETM)and has been widely used in organic light-emitting diodes(OLEDs)because of the large electron mobility and easy fabrication process.However,its low glass transition temperature would lead to poor device stability.In the past decades,various attempts have been carried out to improve its thermal stability though always be accomplished by the reduced electron mobility.Here,we present a molecular engineering to modulate the properties of BPhen,and through which,a versatile BPhen derivative(4,7-bis(naphthaleneb-yl)-1,10-phenanthroline,b-BNPhen)with high thermal stability(glass transition temperature=111.9℃),large electron mobility(7.8×10-4 cm2/(V s)under an electrical field of 4.5×105 V/cm)and excellent n-doping ability with an air-stable metal of Ag is developed and used as multifunctional layers to improve the efficiency and enhance the stability of OLEDs.This work elucidates the great importance of our molecular engineering methodology and device structure optimization strategy,unlocking the potential of 1,10-phenanthroline derivatives towards practical applications.展开更多
文摘The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. The research on the change trend of CCT and the law of extending the change range of CCT will help to further improve the performance of this kind of device. The present work fabricated a series of CT-WOLED devices with a simple structure, which are all composed of two ultra-thin phosphor layers (PO-01 and Flrpic) and a spacer interlayer. The yellow interface exciplex (TCTA/PO-T2T) formed between the spacer layer (PO-T2T) and transmission material (TCTA) in EML will decrease the CCT value at low voltage. The relationship between the energy transfer in EML and CCT change trend is investigated by adjusting the interface exciplexes and the thickness of the interlayer or the phosphor layer in devices A, B and C, respectively. The results demonstrate that a simple OLED device with an interlayer inserted between two ultra-thin phosphor layers can achieve a wider CCT span from 3359 K to 6451 K at voltage increases from 2.75 V to 8.25 V. .
文摘The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, with the increase of voltage, the movement of the recombination zone (RZ) is inevitable because the perfect bipolar host material is difficult to obtain, which will redistribute the energy in the light emitting layer (EML) and affect the stability of the spectrum. We fabricate a series of ternary hybrid WOLEDs with a simple structure by inserting ultra-thin PO-T2T into the blue exciplex (TCTA:TPBi) to form the green interface exciplex. Without considering the movement of RZ, device B2 realizes the dynamic balance energy distribution in EML and stable spectrum by controlling two processes of the Dexter energy transfer and exciton capture. By modifying the doping ratio of the host material, we also find that the broadened RZ is helpful to further improve the spectral stability of the device. When the voltage changes from 3 V to 7 V, the change range of color coordinates is only (0.026, 0.025).
基金support by DST-SERB,Govt.of India(CRG/2020/003699)CKV and KNNU acknowledge support from DST-AISRF program of the Department of Science and Technology,Government of India(DST/INT/AUS/P-74/2017)support from Council of Scientifc and Industrial Research(CSIR),Government of India for the award of a research fellowship.AKS acknowledges support from DST-INSPIRE for the award of a research fellowship.
文摘White organic light-emitting diodes(WOLEDs)have several desirable features,but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures.Herein,we investigate a standard blue emitting hole transporting material(HTM)N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine(NPB)and its exciplex emission upon combining with a suitable electron transporting material(ETM),3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole(TAZ).Blue and yellow OLEDs with simple device structures are developed by using a blend layer,NPB:TAZ,as a blue emitter as well as a host for yellow phosphorescent dopant iridium(III)bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate(PO-01).Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units.The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer(CGL).Judicious choice of the spacer prevents exciton difusion from the blue emitter unit,yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation.This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission.The overall white light emission properties are enhanced,achieving CIE coordinates(0.36,0.39)and color temperature(4643 K)similar to daylight.Employing intermolecular exciplex emission in OLEDs simplifes the device architecture via its dual functionality as a host and as an emitter.
基金supported by the National Natural Science Foundation of China(21788102,22125803,22020102006,21871083)Shanghai Municipal Science and Technology Major Project(2018SHZDZX03)+3 种基金the Program of Shanghai Academic/Technology Research Leader(20XD1421300)the“Shu Guang”Project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(19SG26)the Fundamental Research Funds for the Central Universitiesthe China National Postdoctoral Program for Innovative Talents(BX20220106)。
文摘Metal-free room-temperature phosphorescence(RTP)materials have the characteristics of large Stokes shift,long lifetime,and triplet state transition.They exhibit application potential in various fields,such as bioimaging,computer display,sensor,and anticounterfeiting and have drawn much research interest.Recent work showed that manipulating intermolecular interactions(e.g.,crystallization,polymerization,and rigid matrix)and host-guest assembly to restrain nonradiative transitions and isolate phosphor from oxygen as much as possible is a feasible way to obtain various types of efficient RTP materials.In some cases,intermolecular interactions also facilitated RTP emission by regulating the triplet state.On the other hand,heavy atoms(Br,I,etc.),heteroatoms(N,O,S,etc.),or carbonyls were introduced to the molecular skeleton through molecular engineering to enhance intersystem crossing,which is important for populating the triplet exciton.By comprehensively using the aforesaid strategies,great progress has been made for RTP materials.In this mini-review,we summarized recent advances in organic RTP materials based on manipulating intermolecular interactions.Typical host-guest assembly,hydrogen-bond assembly,energy transfer process,and exciplex emission system-based RTP materials were well illustrated.In summary,the current challenges and prospects for development in this field were presented.
基金the National Natural Science Foundation of China(52372047 and 52003284)for financially supportingthis work.
文摘Comprehensive Summary Duration-tunable afterglow materials have garnered considerable attention in various applications.Herein,carbon dots(CDs)-based long persistent luminescence(LPL)composites with a tunable duration in an ultrawide range of seconds-to-hours levels were designed and prepared for the first time.In contrast to the established CD-based afterglow materials,we reported that CD-based composites exhibit LPL in the form of exciplexes and long-lived charge-separated states,enabling the LPL to be prolonged from several seconds to over one hour,exceeding the typical regulation range(limited to 1 min).Further studies revealed that the relationship between the excited and charge-transfer states of CDs plays a pivotal role in activating the LPL and regulating its duration.Furthermore,these composites exhibited high photoluminescence(PL)quantum yields of up to 60.63%,and their LPL was robust under ambient conditions,even in aqueous media.Their robust and superior LPL performance endows these composites with a strong competitive advantage in dynamic display systems,such as tags for time-resolved data encryption and displays of the remaining time of takeaways.This study offers an approach to preparing CDs-based LPL composites with tunable durations and may provide new insights for the development of rare-earth-free LPL materials.
基金Acknowledgements We sincerely thank Y. Gu, C. L. Yang and H. Xu for their careful testing of the samples. The authors gratefully acknowledge the National Natural Science Foundation of China （Grant Nos. 51333007 and 50973104）, the National Basic Research Program of China （No. 2013CB834805）, the Foundation of Jilin Research Council （Nos.2012ZDGG001, 20130206003GX and 201105028）, and Chinese Academy of Sciences Instrument Project （No. YZ201103） for the support of this research.
文摘High efficient yellow organic light emitting diodes （OLEDs） based on exciplex were reported. The exciplex was formed by 4, 4＇, 4″-tris β-methylphenyl （phenyi） amino]-triphenylamine （m-MTDATA） and 4, 7- diphenyl-1, 10-phenanthroline （BPhen）. The resulting yellow OLEDs exhibited an external quantum efficiency of over 7%, which is attributed to the effective energy back transfer from exciplex triplet state to exciplex singlet state. The maximum power efficiency of 25 lm/W was achieved. Doping a yellow phosphor Ir（bt）2（acac） into m-MTDATA： BPhen blend, a high efficiency device was achieved with a turn-on voltage of 2.1 V, maximum power efficiency and external quantum efficiency of 86.1 lm/W and 20.7%, respectively.
基金supported by the National Key Basic Research and Development Program of China(2017YFA0204501,2016YFB0400702 and 2016YFB0401003)the National Natural Science Foundation of China(51525304 and 61890942)the Fundamental Research Funds for the Central Universities.
文摘4,7-Bisphenyl-1,10-phenanthroline(BPhen)is a promising electron transport material(ETM)and has been widely used in organic light-emitting diodes(OLEDs)because of the large electron mobility and easy fabrication process.However,its low glass transition temperature would lead to poor device stability.In the past decades,various attempts have been carried out to improve its thermal stability though always be accomplished by the reduced electron mobility.Here,we present a molecular engineering to modulate the properties of BPhen,and through which,a versatile BPhen derivative(4,7-bis(naphthaleneb-yl)-1,10-phenanthroline,b-BNPhen)with high thermal stability(glass transition temperature=111.9℃),large electron mobility(7.8×10-4 cm2/(V s)under an electrical field of 4.5×105 V/cm)and excellent n-doping ability with an air-stable metal of Ag is developed and used as multifunctional layers to improve the efficiency and enhance the stability of OLEDs.This work elucidates the great importance of our molecular engineering methodology and device structure optimization strategy,unlocking the potential of 1,10-phenanthroline derivatives towards practical applications.
