The construction of long-range charge-transfer(LRCT)states has emerged as a promising strategy to improve the reverse intersystem crossing(RISC)of multiple resonance thermally activated delayed fluorescence(MR-TADF)em...The construction of long-range charge-transfer(LRCT)states has emerged as a promising strategy to improve the reverse intersystem crossing(RISC)of multiple resonance thermally activated delayed fluorescence(MR-TADF)emitters,yet balancing LRCT with short-range charge-transfer(SRCT)states remains a significant challenge.To address this,we developed a machine learning-based empirical formula to accurately predict whether LRCT/SRCT-type TADF molecules can retain narrowband emission,thereby aiding the design of novel molecules.Guided by this empirical formula,the proof-of-concept emitter DABNA-TP-Di PXZ exhibited fully hybridized LRCT and SRCT states with deep-blue emission peaking at 445 nm and an impressively narrow full width at half maximum(FWHM)of 19 nm.The corresponding device exhibited outstanding performance,achieving a maximum external quantum efficiency(EQE_(max))of 32%,and Commission Internationale de L'Eclairage(CIE)coordinates of(0.14,0.06).Moreover,it delivered a remarkably high chromaticity efficiency of 367 cd/A,representing the highest value reported among LRCT/SRCT type TADF emitters.These results underscore the remarkable efficiency and color purity of DABNA-TP-Di PXZ,demonstrating the effectiveness of our molecular design strategy in advancing high-performance and high-purity deep-blue emitters.展开更多
High-performance deep-blue emitters that meet the BT.2020 standard proposed by the International Telecommunication Union(ITU)for organic light-emitting diodes(OLEDs)remain highly limited.In this work,four deep-blue em...High-performance deep-blue emitters that meet the BT.2020 standard proposed by the International Telecommunication Union(ITU)for organic light-emitting diodes(OLEDs)remain highly limited.In this work,four deep-blue emitters,PP1M,PP2M,PP3M,and PP4M,are designed and synthesized by connecting methylsubstituted biphenyl groups with classical hot exciton building block of phenanthreneimidazole.The introduction of methyl groups contributes to increase the molecular torsion angle and widen the energy gaps for the four compounds.Through appropriate modulation of substitution site,PP3M achieves the highest photoluminescence quantum yield of 85.3%in neat film.As a result,the PP3M-based device exhibits deep-blue light with external quantum efficiency of 7.2%and suppressed efficiency roll-off.The device also shows a small full width at half maximum of 53 nm and the CIE coordinates locate at(0.16,0.04),meeting well with the BT.2020 standard.The high exciton utilization efficiency is primarily ascribed to the hot exciton pathway.This study provides a reliable insight for the design of efficient deep-blue OLEDs with high color purity.展开更多
To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polym...To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.展开更多
Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS...Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS and PPPIS,with hot exciton property are successfully developed.Compared to PPIS,the embedded phenyl bridge in PPPIS is able to effectively increase the overlap of frontier molecular orbitals.In consequence,PPPIS shows higher oscillator strength and significantly enhanced PLQY.PPPIS also achieves better electroluminescence performance in non-doped device,showing deep-blue emission with Commission International de l’Eclairage(CIE)coordinates of(0.153,0.087)and the maximum external quantum efficiency(EQEmax)of 8.5%with minuscule efficiency roll-off.Meanwhile,when PPPIS serves as the host for phosphor PO-01,high-efficiency orange phosphorescent device is obtained with high EQEmax of 29.8%and negligible efficiency roll-off at 1000 cd/m^(2).Further,efficient single-emissive-layer white device is assembled via utilizing PPPIS as a blue emitter as well as the host for PO-01 simultaneously,providing warm-white emission with CIE coordinates of(0.429,0.433)at 1000 cd/m^(2),the forward-viewing EQEmaxof 27.2%and maximum power efficiency(PEmax)of 80.1 lm/W,respectively.Our studies can establish a viable design strategy for deep-blue emitters in high-performance non-doped blue OLEDs and hybrid WOLEDs.展开更多
近年来随着手机薄型化趋势的发展以及对可靠性要求的提高,OLED(Organic Light-Emitting Diode)屏幕孔区出现彩虹纹现象的比例有一定的上升。本文定性、定量地分析了OLED屏幕孔区出现彩虹纹现象的原因,并基于此,建立了一套相对完备的可...近年来随着手机薄型化趋势的发展以及对可靠性要求的提高,OLED(Organic Light-Emitting Diode)屏幕孔区出现彩虹纹现象的比例有一定的上升。本文定性、定量地分析了OLED屏幕孔区出现彩虹纹现象的原因,并基于此,建立了一套相对完备的可以相互交叉印证结果的多维度分析测试方法。对薄膜封装(Thin Film Encapsulation,TFE)膜层结构成分的进一步优化,可以最大限度地降低可靠性测试后出现与孔区彩虹纹相关的暗斑风险。通过裂片,分析了高温高湿实验条件下孔区发生彩虹纹的区域和位置;并以透射电子显微镜(Transmission Electron Microscope,TEM)、飞行时间二次离子质谱(Time of Flight Secondary Ion Mass Spectrometry,TOF-SIMS)和X射线光电子能谱(X-ray Photoelectron Spectroscopy,XPS)系统分析了孔区产生现象的原因。实验结果表明,CVD1(Chemical Vapor Deposition 1)中SiON在高温高湿条件下,会逐步向SiO膜层转化。TEM和TOF-SIMS的结果表明,被氧化后膜层的含氮量小于2%;XPS分峰结果显示,CVD1-2表面的SiON几乎全部转化为SiO膜层。通过将TFE中CVD1-1的SiON膜层折光率从1.72提升为1.76,CVD1-1的SiON膜层被氧化的深度下降了70%。该分析方法的建立不仅解释了孔区CVD膜层被氧化后生成的SiO是造成出现彩虹纹现象的原因,而且提出了彩虹纹区域对OLED面板孔区可靠性的影响。该方案策略为OLED显示未来在车载、IT(Information Technology)、广告牌等具有更高可靠性要求领域的应用提供了相应的解决思路。展开更多
Film morphology of emissive layers is crucial to the performance and stability of solution-processable organic light-emitting diodes(OLEDs). Compared to the interpenetration of conjugated polymer chain,small molecular...Film morphology of emissive layers is crucial to the performance and stability of solution-processable organic light-emitting diodes(OLEDs). Compared to the interpenetration of conjugated polymer chain,small molecular emitter with a flexible side chain always presents easily aggregation upon external treatment, and caused π-electronic coupling, which is undesirable for the efficiency and stability of deep-blue OLEDs. Herein, we proposed a side-chain coupling strategy to enhance the film morphological an emission stability of solution-processable small molecular deep-blue emitter. In contrary to “parent” MC8 TPA,the crosslinkable styryl and vinyl units were introduced as ended unit at the side-chain of Cm TPA and OEYTPA. Interestingly, Cm TPA and OEYTPA films present a relatively stable morphology and uniform deep-blue emission after thermal annealing(160 ℃) in the atmosphere, different to the discontinuous MC8 TPA annealed film. Besides, compared to the Cm TPA and OEYTPA ones, serious polaron formation in the MC8 TPA annealed film also negative to the deep-blue emission, according to transient absorption analysis. Therefore, both Cm TPA and OEYTPA annealed film obtained at 140 ℃ present an excellent deep-blue ASE behavior with a 445 nm, but absence for MC8 TPA ones, associated with the disruption of annealed films. Finally, enhancement of device performance based on Cm TPA and OEYTPA film(~40%)after thermal annealing with a similar performance curves also confirmed the assumption above. Therefore, these results also supported the effectiveness of our side-chain coupling strategy for optoelectronic applications.展开更多
The control of the condensed superstructure of light-emitting conjugated polymers(LCPs)is a crucial factor to obtain high performance and stable organic optoelectronic devices.Side-chain engineering strategy is an eff...The control of the condensed superstructure of light-emitting conjugated polymers(LCPs)is a crucial factor to obtain high performance and stable organic optoelectronic devices.Side-chain engineering strategy is an effective platform to tune inter chain aggregation and photophysical behaviour of LCPs.Herein,we systematically investigated the alkyl-chain branched effecton the conformational transition and photophysical behaviour of polydiarylfluorenes toward efficient blue optoelectronic devices.The branched side chain will improve materials solubility to inhibit interchain aggregation in solution according to DLS and optical analysis,which is useful to obtain high quality film.Therefore,our branched PEODPF,POYDPF pristine film present high luminance efficiency of 36.1%and 39.6%,enhanced about 20%relative to that of PODPF.Compared to the liner-type sides'chain,these branched chains also suppress chain planarization and improve film morphological stability effectively.Interestingly,the branched polymer also had excellent stable amplified spontaneous emission(ASE)behaviour with low threshold(4.72μJ/cm2)and a center peak of 465 nm,even thermal annealing at 220℃in the air atmosphere.Therefore,side-chain branched strategy for LCPs is an effective means to control interchain aggregation,film morphology and photophysical property of LCPs.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
The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by ...The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by the energy gap law and inefficient triplet exciton utilization.In this study,we present a conformation-locking strategy combined with donor engineering to enhance NIR emitters based on a boron-dipyrromethene(BODIPY)scaffold for high-performance solution-processed OLEDs.Two NIR emitters,Ph-BDP-Cz and Ph-BDP-PY,were synthesized by introducing a donor at the α-position of the BODIPY core via a vinyl bridge.This design increases molecular rigidity by promoting HF interactions between vinyl hydrogens and the BF2 group,suppressing twisting and scissoring motions,which results in narrow emission and high photoluminescence quantum yields.Donor engineering also enables fine-tuning of emission wavelengths without broadening the full-width at half-maximum(FWHM),maintaining a narrow emission profile.Using these BODIPY emitters in thermally activated delayed fluorescence(TADF)-sensitized hyperfluorescent OLEDs,we achieved a maximum external quantum efficiency(EQE)of 6.9%with an emission peak at 702 nm and a narrow FWHM of<45 nm.To our knowledge,this represents one of the highest efficiencies among TADF sensitized solution-processed NIR OLEDs,offering a promising path toward the development of sustainable and high-performance NIR optoelectronic devices.展开更多
π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance a...π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.展开更多
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
The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissi...The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissive layers that combine high efficiency with mechanical robustness.Thermally activated delayed fluorescence(TADF)materials have attracted significant attention as third-generation emitters capable of achieving 100%internal quantum efficiency;however,their application in stretchable OLEDs has been limited.In this study,we propose an elastomer doping strategy.Polyurethane(PU)is incorporated into TADF polymers to improve their mechanical flexibility while maintaining a high luminescent efficiency.The resulting composite films exhibited excellent TADF characteristics and remarkable stretchability(75%).OLEDs fabricated from these materials achieved a maximum external quantum efficiency(EQE)of 14.26%and a peak luminance of 73570 cd·m^(-2),with the PUdoped devices showing a significantly suppressed efficiency roll-off.Additionally,a fully stretchable OLED architecture was designed and operated under tensile strain to maintain stable electroluminescent performance.These results demonstrate that elastomer doping is an effective strategy for balancing the mechanical compliance with optoelectronic performance,offering a promising pathway for the development of high-performance stretchable OLEDs for flexible electronics.展开更多
Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-r...Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-resolution pixel architectures.In this study,electropolymerization of 3,4-ethylenedioxythiophene(EDOT)in poly(styrene sulfonate)(PSS-)surfactant-solubilized colloidal media is shown to afford poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)films with robust surface uniformity and stable energy levels suitable for application as hole-injection layers in OLEDs.Systematic investigation reveals that the hole-injection properties of these films are governed primarily by the colloidal chemistry of EDOT/PSS-surfactant-solubilized systems,rather than by conventional electrochemical parameters.This colloidal regulation modulates the film work function over a practically useful range.Incorporation of optimized films into OLEDs leads to enhanced hole injection and improved device performance,with external quantum efficiency increasing from 2.2%to 7.4%and minimal roll-off.Overall,this work demonstrates a feasible example of realizing spin-coating-free hole-injection layers,offering a potential direction for the development of electrodeposited injection layers for OLEDs.展开更多
基金supported by the Wuhan Joint Innovation Laboratory of Advanced Display Industry(2024010902040449)the National Natural Science Foundation of China(52473175)+1 种基金the Science and Technology Department of Hubei Province(2024BAB014)the Shenzhen Science and Technology Program(JCYJ20220530161208020,JCYJ20240813153419026)。
文摘The construction of long-range charge-transfer(LRCT)states has emerged as a promising strategy to improve the reverse intersystem crossing(RISC)of multiple resonance thermally activated delayed fluorescence(MR-TADF)emitters,yet balancing LRCT with short-range charge-transfer(SRCT)states remains a significant challenge.To address this,we developed a machine learning-based empirical formula to accurately predict whether LRCT/SRCT-type TADF molecules can retain narrowband emission,thereby aiding the design of novel molecules.Guided by this empirical formula,the proof-of-concept emitter DABNA-TP-Di PXZ exhibited fully hybridized LRCT and SRCT states with deep-blue emission peaking at 445 nm and an impressively narrow full width at half maximum(FWHM)of 19 nm.The corresponding device exhibited outstanding performance,achieving a maximum external quantum efficiency(EQE_(max))of 32%,and Commission Internationale de L'Eclairage(CIE)coordinates of(0.14,0.06).Moreover,it delivered a remarkably high chromaticity efficiency of 367 cd/A,representing the highest value reported among LRCT/SRCT type TADF emitters.These results underscore the remarkable efficiency and color purity of DABNA-TP-Di PXZ,demonstrating the effectiveness of our molecular design strategy in advancing high-performance and high-purity deep-blue emitters.
文摘High-performance deep-blue emitters that meet the BT.2020 standard proposed by the International Telecommunication Union(ITU)for organic light-emitting diodes(OLEDs)remain highly limited.In this work,four deep-blue emitters,PP1M,PP2M,PP3M,and PP4M,are designed and synthesized by connecting methylsubstituted biphenyl groups with classical hot exciton building block of phenanthreneimidazole.The introduction of methyl groups contributes to increase the molecular torsion angle and widen the energy gaps for the four compounds.Through appropriate modulation of substitution site,PP3M achieves the highest photoluminescence quantum yield of 85.3%in neat film.As a result,the PP3M-based device exhibits deep-blue light with external quantum efficiency of 7.2%and suppressed efficiency roll-off.The device also shows a small full width at half maximum of 53 nm and the CIE coordinates locate at(0.16,0.04),meeting well with the BT.2020 standard.The high exciton utilization efficiency is primarily ascribed to the hot exciton pathway.This study provides a reliable insight for the design of efficient deep-blue OLEDs with high color purity.
基金the support from the Jiangsu Provincial Senior Talent Program (Dengfeng,Jiangsu University)the support from the National Key R&D Program of China (No.2024YFB3612600)+3 种基金the National Natural Science Foundation of China (Nos.22275098,62288102)Basic Research Program of Jiangsu (No.BK20243057)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (No.NY222097)the National Natural Science Foundation of China (No.62205035)。
文摘To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.
基金financial support from National Natural Science Foundation of China(No.22075100)the Jilin Provincial Science and Technology Department(No.20220201082GX)+2 种基金the China Postdoctoral Science Foundation(Nos.2022TQ0111,2023M731267)Sichuan Science and Technology Program(No.2023NSFSC0985)Scientific Research Foundation of Chengdu University of Information Technology(No.KYTZ202174)and the Changsha Automobile Innovation Research Institute。
文摘Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS and PPPIS,with hot exciton property are successfully developed.Compared to PPIS,the embedded phenyl bridge in PPPIS is able to effectively increase the overlap of frontier molecular orbitals.In consequence,PPPIS shows higher oscillator strength and significantly enhanced PLQY.PPPIS also achieves better electroluminescence performance in non-doped device,showing deep-blue emission with Commission International de l’Eclairage(CIE)coordinates of(0.153,0.087)and the maximum external quantum efficiency(EQEmax)of 8.5%with minuscule efficiency roll-off.Meanwhile,when PPPIS serves as the host for phosphor PO-01,high-efficiency orange phosphorescent device is obtained with high EQEmax of 29.8%and negligible efficiency roll-off at 1000 cd/m^(2).Further,efficient single-emissive-layer white device is assembled via utilizing PPPIS as a blue emitter as well as the host for PO-01 simultaneously,providing warm-white emission with CIE coordinates of(0.429,0.433)at 1000 cd/m^(2),the forward-viewing EQEmaxof 27.2%and maximum power efficiency(PEmax)of 80.1 lm/W,respectively.Our studies can establish a viable design strategy for deep-blue emitters in high-performance non-doped blue OLEDs and hybrid WOLEDs.
文摘近年来随着手机薄型化趋势的发展以及对可靠性要求的提高,OLED(Organic Light-Emitting Diode)屏幕孔区出现彩虹纹现象的比例有一定的上升。本文定性、定量地分析了OLED屏幕孔区出现彩虹纹现象的原因,并基于此,建立了一套相对完备的可以相互交叉印证结果的多维度分析测试方法。对薄膜封装(Thin Film Encapsulation,TFE)膜层结构成分的进一步优化,可以最大限度地降低可靠性测试后出现与孔区彩虹纹相关的暗斑风险。通过裂片,分析了高温高湿实验条件下孔区发生彩虹纹的区域和位置;并以透射电子显微镜(Transmission Electron Microscope,TEM)、飞行时间二次离子质谱(Time of Flight Secondary Ion Mass Spectrometry,TOF-SIMS)和X射线光电子能谱(X-ray Photoelectron Spectroscopy,XPS)系统分析了孔区产生现象的原因。实验结果表明,CVD1(Chemical Vapor Deposition 1)中SiON在高温高湿条件下,会逐步向SiO膜层转化。TEM和TOF-SIMS的结果表明,被氧化后膜层的含氮量小于2%;XPS分峰结果显示,CVD1-2表面的SiON几乎全部转化为SiO膜层。通过将TFE中CVD1-1的SiON膜层折光率从1.72提升为1.76,CVD1-1的SiON膜层被氧化的深度下降了70%。该分析方法的建立不仅解释了孔区CVD膜层被氧化后生成的SiO是造成出现彩虹纹现象的原因,而且提出了彩虹纹区域对OLED面板孔区可靠性的影响。该方案策略为OLED显示未来在车载、IT(Information Technology)、广告牌等具有更高可靠性要求领域的应用提供了相应的解决思路。
基金supported by the National Natural Science Foundation of China (Nos.22075136,61874053)National Key Research and Development Program of China (No.2020YFA0709900)+5 种基金Natural Science Funds of the Education Committee of Jiangsu Province (No.18KJA430009)Natural Science Foundation of Jiangsu Province (No.BK20200700)“High-Level Talents in Six Industries” of Jiangsu Province (No.XYDXX-019)Chain Postdoctoral Science Foundation (No.2021M692623)the open research fund from State Key Laboratory of Supramolecular Structure and Materials (No.sklssm202108)Anhui Province Key Laboratory of Environmentfriendly Polymer Materials and Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology。
文摘Film morphology of emissive layers is crucial to the performance and stability of solution-processable organic light-emitting diodes(OLEDs). Compared to the interpenetration of conjugated polymer chain,small molecular emitter with a flexible side chain always presents easily aggregation upon external treatment, and caused π-electronic coupling, which is undesirable for the efficiency and stability of deep-blue OLEDs. Herein, we proposed a side-chain coupling strategy to enhance the film morphological an emission stability of solution-processable small molecular deep-blue emitter. In contrary to “parent” MC8 TPA,the crosslinkable styryl and vinyl units were introduced as ended unit at the side-chain of Cm TPA and OEYTPA. Interestingly, Cm TPA and OEYTPA films present a relatively stable morphology and uniform deep-blue emission after thermal annealing(160 ℃) in the atmosphere, different to the discontinuous MC8 TPA annealed film. Besides, compared to the Cm TPA and OEYTPA ones, serious polaron formation in the MC8 TPA annealed film also negative to the deep-blue emission, according to transient absorption analysis. Therefore, both Cm TPA and OEYTPA annealed film obtained at 140 ℃ present an excellent deep-blue ASE behavior with a 445 nm, but absence for MC8 TPA ones, associated with the disruption of annealed films. Finally, enhancement of device performance based on Cm TPA and OEYTPA film(~40%)after thermal annealing with a similar performance curves also confirmed the assumption above. Therefore, these results also supported the effectiveness of our side-chain coupling strategy for optoelectronic applications.
基金supported by the National Natural Science Foundation of China(Nos.61874053,21774061,91833306)Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,PAPD(No.YX03002)+10 种基金the Six Peak Talents Foundation of Jiangsu Province(No.XCL-CXTD-009)Natural Science Funds of the Education Committee of Jiangsu Province(No.18KJA430009)"High-Level Talents in Six Industries"of Jiangsu Province(No.XYDXX-019)Program for Postgraduates Research Innovation in University of Jiangsu Province(No.KYCX17_0752)the open research fund from Key Laboratory for Organic Electronics and Information Display&and State Key Laboratory of Supramolecular Structure and Materials(No.sklssm2019017)Overseas Merit Foundation of Science and Technology of Nanjingfinancial support from the Regional Government of Madrid through NMAT2D-CM Project(No.S2018/NMT-4511)the Spanish Ministry of Economy and Competitiveness through project RTI2018-097508-B-I00through the Severo Ochoa Program for Centers of Excellence(No.SEV-2016-0686)the Campus of International Excellence(CEI)UAM+CSICthe China Scholarship Council(No.201608390023)for a PhD sponsorship
文摘The control of the condensed superstructure of light-emitting conjugated polymers(LCPs)is a crucial factor to obtain high performance and stable organic optoelectronic devices.Side-chain engineering strategy is an effective platform to tune inter chain aggregation and photophysical behaviour of LCPs.Herein,we systematically investigated the alkyl-chain branched effecton the conformational transition and photophysical behaviour of polydiarylfluorenes toward efficient blue optoelectronic devices.The branched side chain will improve materials solubility to inhibit interchain aggregation in solution according to DLS and optical analysis,which is useful to obtain high quality film.Therefore,our branched PEODPF,POYDPF pristine film present high luminance efficiency of 36.1%and 39.6%,enhanced about 20%relative to that of PODPF.Compared to the liner-type sides'chain,these branched chains also suppress chain planarization and improve film morphological stability effectively.Interestingly,the branched polymer also had excellent stable amplified spontaneous emission(ASE)behaviour with low threshold(4.72μJ/cm2)and a center peak of 465 nm,even thermal annealing at 220℃in the air atmosphere.Therefore,side-chain branched strategy for LCPs is an effective means to control interchain aggregation,film morphology and photophysical property of LCPs.
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.
基金financially supported by Natural Science Foundation of Guangdong Province(No.2022B1515020041)National Natural Science Foundation of China(Nos.22350410384,52273179,52303228,U23A20594)+1 种基金Guangzhou Basic and Applied Basic Research(No.2023A04J1374)the Instrumental Analysis Center of Guangdong University of Technology for their support。
文摘The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by the energy gap law and inefficient triplet exciton utilization.In this study,we present a conformation-locking strategy combined with donor engineering to enhance NIR emitters based on a boron-dipyrromethene(BODIPY)scaffold for high-performance solution-processed OLEDs.Two NIR emitters,Ph-BDP-Cz and Ph-BDP-PY,were synthesized by introducing a donor at the α-position of the BODIPY core via a vinyl bridge.This design increases molecular rigidity by promoting HF interactions between vinyl hydrogens and the BF2 group,suppressing twisting and scissoring motions,which results in narrow emission and high photoluminescence quantum yields.Donor engineering also enables fine-tuning of emission wavelengths without broadening the full-width at half-maximum(FWHM),maintaining a narrow emission profile.Using these BODIPY emitters in thermally activated delayed fluorescence(TADF)-sensitized hyperfluorescent OLEDs,we achieved a maximum external quantum efficiency(EQE)of 6.9%with an emission peak at 702 nm and a narrow FWHM of<45 nm.To our knowledge,this represents one of the highest efficiencies among TADF sensitized solution-processed NIR OLEDs,offering a promising path toward the development of sustainable and high-performance NIR optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Nos.22105099 and 61874053)Natural Science Foundation of Jiangsu Province(No.BK20200700)+2 种基金the China Postdoctoral Science Foundation(No.2022M711591)the open research fund from Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology(No.OMST202101)the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology).
文摘π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.
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supported by the National Natural Science Foundation of China(Nos.T2441002,22525506,U24A20137,and U22A6002)Strategic Priority Research Program of CAS(No.XDB0520101)+1 种基金National Key R&D Program of China(No.2023YFB3609000)CAS Project for Young Scientists in Basic Research(No.YSBR-053)。
文摘The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic lightemitting diodes(OLEDs).A critical challenge in this field is the creation of emissive layers that combine high efficiency with mechanical robustness.Thermally activated delayed fluorescence(TADF)materials have attracted significant attention as third-generation emitters capable of achieving 100%internal quantum efficiency;however,their application in stretchable OLEDs has been limited.In this study,we propose an elastomer doping strategy.Polyurethane(PU)is incorporated into TADF polymers to improve their mechanical flexibility while maintaining a high luminescent efficiency.The resulting composite films exhibited excellent TADF characteristics and remarkable stretchability(75%).OLEDs fabricated from these materials achieved a maximum external quantum efficiency(EQE)of 14.26%and a peak luminance of 73570 cd·m^(-2),with the PUdoped devices showing a significantly suppressed efficiency roll-off.Additionally,a fully stretchable OLED architecture was designed and operated under tensile strain to maintain stable electroluminescent performance.These results demonstrate that elastomer doping is an effective strategy for balancing the mechanical compliance with optoelectronic performance,offering a promising pathway for the development of high-performance stretchable OLEDs for flexible electronics.
基金supported by the National Key R&D Program of China(No.2020YFA0714604)the Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates(No.2023B1212060003)+1 种基金the SSL Sci-tech Commissioner Program(No.20234383-01KCJ-G)the National Natural Science Foundation of China(No.92463310)。
文摘Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-resolution pixel architectures.In this study,electropolymerization of 3,4-ethylenedioxythiophene(EDOT)in poly(styrene sulfonate)(PSS-)surfactant-solubilized colloidal media is shown to afford poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)films with robust surface uniformity and stable energy levels suitable for application as hole-injection layers in OLEDs.Systematic investigation reveals that the hole-injection properties of these films are governed primarily by the colloidal chemistry of EDOT/PSS-surfactant-solubilized systems,rather than by conventional electrochemical parameters.This colloidal regulation modulates the film work function over a practically useful range.Incorporation of optimized films into OLEDs leads to enhanced hole injection and improved device performance,with external quantum efficiency increasing from 2.2%to 7.4%and minimal roll-off.Overall,this work demonstrates a feasible example of realizing spin-coating-free hole-injection layers,offering a potential direction for the development of electrodeposited injection layers for OLEDs.
