Abundant efforts have been devoted to improving the efficiency of organic light-emitting diodes(OLEDs),however,approaches to control the device efficiency roll-off are still extremely limited,especially in nondoped bl...Abundant efforts have been devoted to improving the efficiency of organic light-emitting diodes(OLEDs),however,approaches to control the device efficiency roll-off are still extremely limited,especially in nondoped blue OLEDs.In this work,three blue emitters(TAT,TAMT and TAMT-CN)with"hot exciton"properties are designed and synthesized based on[1,2,4]triazolo[1,5-a]pyridine(TP)as a regulating unit as well as anthracene-triphenylamine(An-TPA)as the chromophore.By adjusting the linkage mode and modifying the TP unit,the excited state properties,carrier transfer abilities,horizontal orientation,and device efficiency roll-off were precisely controlled.Among these materials,emitters that directly connect the fused TP unit exhibit balanced charge-transporting ability,higher photoluminescent quantum yield and improved horizontal orientation,resulting in better electroluminescence(EL)performance in non-doped blue OLEDs.As a result,non-doped blue OLEDs exhibit excellent performance with external quantum efficiencies of over 6%,brightness of over 30,000 cd/m2and EL peaks of around 476 nm.More importantly,the device based on TAMT-CN exhibits an ultra-low efficiency roll-off of 2.97%at a high brightness of10,000 cd/m2.The accessible molecular unit and feasible design strategy in this work are of great significance for designing highly efficient and ultra-low efficiency roll-off non-doped blue OLEDs.展开更多
Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic materia...Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic material with blue-shifted mechanochromic properties.Compounds 2b and 2c presented opposite mechanochromic trends.For 2b,the enol-form emission enhanced,and the ketoform emission blue-shift after grinding.In contrast,2c exhibited the weak enol-form emission disappeared and the keto-form emission slightly red-shift after grinding treatments.The estrone-containing2b-based water-dispersed nanoparticles(NPs)exhibit apparent dual-emission and were applied for fluorescence images.In addition,bis(TPA)-containing 2c-based devices exhibit dual-emission with good performance and a singlet exciton yield of 92%,which breaks through the theoretical upper limit of 25%in conventional fluorescent OLEDs.This is one of the highest exciton utilization values recorded for the ESIPT molecules with a dual emission system.展开更多
Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)P...Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)Pt(acac) were prepared and characterized,in which(2-(4',6'-difluorophenyl)pyridinato-N,C2')(2,4-pentanedionato-0,0)Pt(Ⅱ) was used as the planar emission core and 9-(4-(phenylsulfonyl)phenyl)-9 H-carbazole(DC) was regard as the bent pendent.Both platinum complexes showed bright emission in solution and solid state,concomitant with charming external-stimuli-responsive emission under mechanical grinding,organic solvent vapors and pressure.The change emission color spanned from yellow to near-infrared region.Using the platinum complexes as the dopant,solution processable organic light-emitting diodes(OLEDs) were fabricated and a maximum external quantum efficiency of ~18% was achieved,which is the highest value among the reported solution-processable OLEDs based on externalstimuli-responsive luminescence.This research demonstrated that platinum complex can show promising stimuli responsive emission via ingenious molecular design,indicating a novel way for developing the smart materials in semiconductor filed.展开更多
The effect of a benzimidazole derivative(TPBI)electron injection layer(EIL)on the performance of Alga based organic light-emitting devices(OLEDs)with a Cs_(2)C0_(3)/Al cathode is investigated.An increasing current den...The effect of a benzimidazole derivative(TPBI)electron injection layer(EIL)on the performance of Alga based organic light-emitting devices(OLEDs)with a Cs_(2)C0_(3)/Al cathode is investigated.An increasing current density from 71.9mA/cm2 to 188.3mA/cm^(2),and an enhanced electroluminescence(EL)efficiency from 3.2cd/A to 3.64 cd/A at 9 V are found when a thin TPBI layer(5 nm)is inserted at the Alq_(3)/Cs_(2)C0_(3)interface.After further increasing the TPBI thickness to 10 run,OLEDs display a further increase in EL efficiency to 4.53cd/A.Our experiment suggests that the TPBI thin layer at the Alq_(3)/Cs_(2)C0_(3)interface facilitates the electron injection and is also involved with hole-blocking and exciton confinement.展开更多
2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED...2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.展开更多
A simple method to determine the traps＇ density of state （DOS） in organic light-emitting diodes （OLEDs） by manipulating the current-voltage （I-V） characteristic of the devices at room temperature is introduced....A simple method to determine the traps＇ density of state （DOS） in organic light-emitting diodes （OLEDs） by manipulating the current-voltage （I-V） characteristic of the devices at room temperature is introduced. In particular, the trap-dependent space-charge limited current formula is simplified to obtain effective density of traps. In this study, poly[（9,9-di-n-octylfluorenyl-2,7-diyl）-alt-（benzo[2,1,3]thiadiazol-4,8-diyl）] （F8BT） and 2- Methoxy-5-（3＇, 7＇-dimethyloctyloxy） benzene-l,4-diacetonitrile （0C1 Clo-PPV） are selected as the OLEDs emissive layer. The trap DOS of F8BT- and OC1Clo-PPV-based OLEDs are calculated in the magnitudes of 1024 m^-3 and 1023 m^-3, respectively. In addition, the results agree with the other conventional method which is used to determine the trap DOS in OLEDs. This calculation technique may serve as a robust and reliable approach to obtain the trap DOS in OLEDs at room temperature.展开更多
Electrodeposition is an old and effective method for the fabrication of organic films.Though electrodeposited organic films have been widely used in various applications,highly luminescent films have been a great chal...Electrodeposition is an old and effective method for the fabrication of organic films.Though electrodeposited organic films have been widely used in various applications,highly luminescent films have been a great challenge because the electrochemically doped state may strongly quench the fluorescence.In the first part of this review,the organic electrodeposition techniques,along with general electropolymerization and other special electrodepositions are introduced.In the second part of the review,we describe how to electrochemically fabricate luminescent films for organic light-emitting diodes(OLEDs).With the rational molecular design and well-controlled electrodeposition process,we have not only demonstrated high-performance OLEDs,but also paved a promising way to practice active-matrix OLEDs(AMOLEDs)and super-resolution OLEDs.In particular,RGB 3×3 array OLEDs based on active-matrix substrates,RGB passive-matrix OLEDs(PMOLEDs)with a resolution of 210 ppi,and monochromatic OLEDs with a super-resolution of 2822 ppi have been successfully fabricated.It is highly anticipated that the organic electrodeposition technology is of comparable or perhaps even higher contenders in manufacturing and downscaling OLEDs and AMOLEDs with low-cost and high-resolution for the human-computer interaction fields such as augmented reality(AR),virtual reality(VR),etc.展开更多
In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters...In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters, we studied the performance of device and its mechanism. A solution processed OLED with a structure of indium tin oxide(ITO, 150 nm)/PEDOT:PSS(30 nm)/CBP:4 Cz IPN-x%:4 Cz PN-y%(30 nm)/TPBi(40 nm)/Li F(1 nm)/Al(100 nm) was fabricated. The current efficiencies of 26.6 cd/A and 26.4 cd/A were achieved by the devices with dopant ratio of 6% 4 Cz IPN:2% 4 Cz PN and 2% 4 Cz IPN:6% 4 Cz PN in emitting material layer(EML), respectively. By investigating the tendency of current density change in devices with different doping ratio, we suggested that the enhancement of the current efficiency should be due to the charge transport balance improvement induced by assist dopant in EML.展开更多
The calculation of the external quantum efficiency(η_ ext ) of organic light-emitting devices(OLEDs) is presented theoretically. The basic idea is to obtain η_ ext by calculating the fraction of the generated light ...The calculation of the external quantum efficiency(η_ ext ) of organic light-emitting devices(OLEDs) is presented theoretically. The basic idea is to obtain η_ ext by calculating the fraction of the generated light that can escape through the top surface and the average transmittance over the escape cone. During the calculation, the effects of the interference, absorption and multiple reflections are neglected. Then a result of a typical 8-tris-hydroxyquinoline aluminum(Alq_ 3 )-based OLEDs on a planar glass substrate is obtained. And a twice increase in η_ ext can be achieved by using a high-index-glass substrate with an antireflection coating(SiO_ 2 ) on substrate surface.展开更多
The effect of LiF thickness on the electrical and luminescent characteristics in OLEDs has been studied by carefully varying thickness value range from 0 nm to 1.2 nm. It’s interesting to find that the device with 0....The effect of LiF thickness on the electrical and luminescent characteristics in OLEDs has been studied by carefully varying thickness value range from 0 nm to 1.2 nm. It’s interesting to find that the device with 0.2 nm LiF layer performs the largest current and comparative lower luminescent efficiency, while the one with 0.6 nm LiF performs another current peak (lower than that of device with 0.2 nm LiF layer) but the highest luminescent efficiency in all devices. Here the much enhanced electron injection and destructive efficiency for 0.2 nm LiF device are understood by the chemical interaction model at cathode interface, while the fairly increased electron injection and much improved efficiency for 0.6 nm LiF device would be interpreted by other mechanisms, and LiF plays a protective part in preventing the deposition-induce photoluminescence from quenching by Al cathode.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.52273187 and 51973107)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme 2019(No.GDUPS2019)。
文摘Abundant efforts have been devoted to improving the efficiency of organic light-emitting diodes(OLEDs),however,approaches to control the device efficiency roll-off are still extremely limited,especially in nondoped blue OLEDs.In this work,three blue emitters(TAT,TAMT and TAMT-CN)with"hot exciton"properties are designed and synthesized based on[1,2,4]triazolo[1,5-a]pyridine(TP)as a regulating unit as well as anthracene-triphenylamine(An-TPA)as the chromophore.By adjusting the linkage mode and modifying the TP unit,the excited state properties,carrier transfer abilities,horizontal orientation,and device efficiency roll-off were precisely controlled.Among these materials,emitters that directly connect the fused TP unit exhibit balanced charge-transporting ability,higher photoluminescent quantum yield and improved horizontal orientation,resulting in better electroluminescence(EL)performance in non-doped blue OLEDs.As a result,non-doped blue OLEDs exhibit excellent performance with external quantum efficiencies of over 6%,brightness of over 30,000 cd/m2and EL peaks of around 476 nm.More importantly,the device based on TAMT-CN exhibits an ultra-low efficiency roll-off of 2.97%at a high brightness of10,000 cd/m2.The accessible molecular unit and feasible design strategy in this work are of great significance for designing highly efficient and ultra-low efficiency roll-off non-doped blue OLEDs.
基金Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology(No.BM2012110)the fundamental research funds for the central universities(No.2023CDJYGRH-YB17)+4 种基金the Venture&Innovation Support Program for Chongqing Overseas Returnees(No.cx2022061)the Natural Science Foundation of Chongqing(No.CSTB2022NSCQ-MSX1123)the Chongqing Talents:Exceptional Young Talents Project(No.cstc2021ycjh-bgzxm0067)Changzhou University,Advanced Catalysis and Green Manufacturing Collaborative Innovation Center(No.ACGM2022–10–10)National Natural Science Foundation of China(Nos.21702019,62174160)for financial support。
文摘Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic material with blue-shifted mechanochromic properties.Compounds 2b and 2c presented opposite mechanochromic trends.For 2b,the enol-form emission enhanced,and the ketoform emission blue-shift after grinding.In contrast,2c exhibited the weak enol-form emission disappeared and the keto-form emission slightly red-shift after grinding treatments.The estrone-containing2b-based water-dispersed nanoparticles(NPs)exhibit apparent dual-emission and were applied for fluorescence images.In addition,bis(TPA)-containing 2c-based devices exhibit dual-emission with good performance and a singlet exciton yield of 92%,which breaks through the theoretical upper limit of 25%in conventional fluorescent OLEDs.This is one of the highest exciton utilization values recorded for the ESIPT molecules with a dual emission system.
基金Patent Industrialization Project of Shaanxi Province(No.2005ZZ-04)Industrialization Project of Shaanxi Education Office(No.06JC23)Patent Scientific Research Project of Shaanxi Education Office(No.07JK191)
基金Financial support was from the National Natural Science Foundation of China(Nos.51773021,51911530197,U1663229)Six Talent Peaks Project in Jiangsu Province(No.XCL-102)the Talent Project of Jiangsu Specially-Appointed Professor,Natural Science Fund for Colleges and Universities in Jiangsu Province(No.19KJA430002)。
文摘Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)Pt(acac) were prepared and characterized,in which(2-(4',6'-difluorophenyl)pyridinato-N,C2')(2,4-pentanedionato-0,0)Pt(Ⅱ) was used as the planar emission core and 9-(4-(phenylsulfonyl)phenyl)-9 H-carbazole(DC) was regard as the bent pendent.Both platinum complexes showed bright emission in solution and solid state,concomitant with charming external-stimuli-responsive emission under mechanical grinding,organic solvent vapors and pressure.The change emission color spanned from yellow to near-infrared region.Using the platinum complexes as the dopant,solution processable organic light-emitting diodes(OLEDs) were fabricated and a maximum external quantum efficiency of ~18% was achieved,which is the highest value among the reported solution-processable OLEDs based on externalstimuli-responsive luminescence.This research demonstrated that platinum complex can show promising stimuli responsive emission via ingenious molecular design,indicating a novel way for developing the smart materials in semiconductor filed.
基金Supported by the National Natural Science Foundation of China under Grant No 20972097Guangdong-Provincial Natural Science Foundation(No 031805)+2 种基金the Major Program in Key Field of Guangdong Province Government(No 2003-03)Science and Technology Program of Shenzhen(No 2006-2007)the Project 000011 Supported by SZU R/D Fund,Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province.
文摘The effect of a benzimidazole derivative(TPBI)electron injection layer(EIL)on the performance of Alga based organic light-emitting devices(OLEDs)with a Cs_(2)C0_(3)/Al cathode is investigated.An increasing current density from 71.9mA/cm2 to 188.3mA/cm^(2),and an enhanced electroluminescence(EL)efficiency from 3.2cd/A to 3.64 cd/A at 9 V are found when a thin TPBI layer(5 nm)is inserted at the Alq_(3)/Cs_(2)C0_(3)interface.After further increasing the TPBI thickness to 10 run,OLEDs display a further increase in EL efficiency to 4.53cd/A.Our experiment suggests that the TPBI thin layer at the Alq_(3)/Cs_(2)C0_(3)interface facilitates the electron injection and is also involved with hole-blocking and exciton confinement.
基金supported by National Natural Science Foundation of China(No. 61605158)the Science and TechnologyDepartment of Shaanxi Province(No. 2016JQ2028)the Education Department of Shaanxi Province(No. 16JK1790)
文摘2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.
基金Supported by the Science Fund under Grant No SF019-2013the Fundamental Research Grant Scheme under Grant No FP033-2013B+1 种基金the Postgraduate Research Fund under Grant No PG107-2015Athe University Malaya Research Grant under Grant No RP026B-15AFR
文摘A simple method to determine the traps＇ density of state （DOS） in organic light-emitting diodes （OLEDs） by manipulating the current-voltage （I-V） characteristic of the devices at room temperature is introduced. In particular, the trap-dependent space-charge limited current formula is simplified to obtain effective density of traps. In this study, poly[（9,9-di-n-octylfluorenyl-2,7-diyl）-alt-（benzo[2,1,3]thiadiazol-4,8-diyl）] （F8BT） and 2- Methoxy-5-（3＇, 7＇-dimethyloctyloxy） benzene-l,4-diacetonitrile （0C1 Clo-PPV） are selected as the OLEDs emissive layer. The trap DOS of F8BT- and OC1Clo-PPV-based OLEDs are calculated in the magnitudes of 1024 m^-3 and 1023 m^-3, respectively. In addition, the results agree with the other conventional method which is used to determine the trap DOS in OLEDs. This calculation technique may serve as a robust and reliable approach to obtain the trap DOS in OLEDs at room temperature.
基金financially supported by the National Natural Science Foundation of China(Nos.U20A6002 and 21733005)the National Key R&D Program of China(No.2020YFA0714604)+1 种基金the Basic and Applied Basic Research Major Program of Guangdong Province(No.2019B030302007)Research and Development Funds for Science and Technology Program of Guangzhou(No.202007020004)。
文摘Electrodeposition is an old and effective method for the fabrication of organic films.Though electrodeposited organic films have been widely used in various applications,highly luminescent films have been a great challenge because the electrochemically doped state may strongly quench the fluorescence.In the first part of this review,the organic electrodeposition techniques,along with general electropolymerization and other special electrodepositions are introduced.In the second part of the review,we describe how to electrochemically fabricate luminescent films for organic light-emitting diodes(OLEDs).With the rational molecular design and well-controlled electrodeposition process,we have not only demonstrated high-performance OLEDs,but also paved a promising way to practice active-matrix OLEDs(AMOLEDs)and super-resolution OLEDs.In particular,RGB 3×3 array OLEDs based on active-matrix substrates,RGB passive-matrix OLEDs(PMOLEDs)with a resolution of 210 ppi,and monochromatic OLEDs with a super-resolution of 2822 ppi have been successfully fabricated.It is highly anticipated that the organic electrodeposition technology is of comparable or perhaps even higher contenders in manufacturing and downscaling OLEDs and AMOLEDs with low-cost and high-resolution for the human-computer interaction fields such as augmented reality(AR),virtual reality(VR),etc.
基金supported by the National High Technology Research and Development Program of China (No.2012AA011901)the National Program on Key Basic Research Project 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In this paper, co-doping method is used to improve the current efficiency of solution-processed organic light-emitting diodes(OLEDs). By changing the ratio of two thermally activated delayed fluorescent(TADF) emitters, we studied the performance of device and its mechanism. A solution processed OLED with a structure of indium tin oxide(ITO, 150 nm)/PEDOT:PSS(30 nm)/CBP:4 Cz IPN-x%:4 Cz PN-y%(30 nm)/TPBi(40 nm)/Li F(1 nm)/Al(100 nm) was fabricated. The current efficiencies of 26.6 cd/A and 26.4 cd/A were achieved by the devices with dopant ratio of 6% 4 Cz IPN:2% 4 Cz PN and 2% 4 Cz IPN:6% 4 Cz PN in emitting material layer(EML), respectively. By investigating the tendency of current density change in devices with different doping ratio, we suggested that the enhancement of the current efficiency should be due to the charge transport balance improvement induced by assist dopant in EML.
基金National Natural Science Foundation of China(60207003 and 60376028) National"973"Project of China(2003cb314703)
文摘The calculation of the external quantum efficiency(η_ ext ) of organic light-emitting devices(OLEDs) is presented theoretically. The basic idea is to obtain η_ ext by calculating the fraction of the generated light that can escape through the top surface and the average transmittance over the escape cone. During the calculation, the effects of the interference, absorption and multiple reflections are neglected. Then a result of a typical 8-tris-hydroxyquinoline aluminum(Alq_ 3 )-based OLEDs on a planar glass substrate is obtained. And a twice increase in η_ ext can be achieved by using a high-index-glass substrate with an antireflection coating(SiO_ 2 ) on substrate surface.
文摘The effect of LiF thickness on the electrical and luminescent characteristics in OLEDs has been studied by carefully varying thickness value range from 0 nm to 1.2 nm. It’s interesting to find that the device with 0.2 nm LiF layer performs the largest current and comparative lower luminescent efficiency, while the one with 0.6 nm LiF performs another current peak (lower than that of device with 0.2 nm LiF layer) but the highest luminescent efficiency in all devices. Here the much enhanced electron injection and destructive efficiency for 0.2 nm LiF device are understood by the chemical interaction model at cathode interface, while the fairly increased electron injection and much improved efficiency for 0.6 nm LiF device would be interpreted by other mechanisms, and LiF plays a protective part in preventing the deposition-induce photoluminescence from quenching by Al cathode.
