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
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
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
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
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 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
为解决传统初始地应力场反演方法存在边界条件筛选能力弱、易受数据过拟合干扰以及难以解析多重边界相互作用的问题,提出一种基于LASSO-OLS(least absolute shrinkage and selection operator-ordinary least squares)的两阶段初始地应...为解决传统初始地应力场反演方法存在边界条件筛选能力弱、易受数据过拟合干扰以及难以解析多重边界相互作用的问题,提出一种基于LASSO-OLS(least absolute shrinkage and selection operator-ordinary least squares)的两阶段初始地应力场反演方法。该方法首先通过对候选边界条件应力矩阵和实测应力矩阵进行Frobenius范数标准化处理,消除不同边界条件数据量级差异的影响;然后,利用LASSO回归的L1正则化约束,从候选边界条件的回归系数路径图中筛选关键影响因素,剔除冗余与弱相关项;最后,针对筛选出的核心变量,采用普通最小二乘回归进行无偏估计,构建兼具稀疏性与准确性的地应力场反演模型。研究结果表明:1)在工程应用实例中,借助LASSO回归从11个候选边界条件中筛选出5个关键因素,显著降低模型复杂度;2)模型正则化参数在标准误差内取值,拟合结果能够保持较高的复相关系数(R=0.995 2),表明筛选后的边界条件有效捕捉了初始地应力场特征;3)初始地应力场反演模型通过LASSO回归筛选,在解析多重边界相互作用时表现出较高的稳定性和物理合理性;4)与传统方法相比,该方法能有效避免初始地应力场反演出现过拟合问题,提高反演结果的鲁棒性。展开更多
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.
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.
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。
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.
文摘为解决传统初始地应力场反演方法存在边界条件筛选能力弱、易受数据过拟合干扰以及难以解析多重边界相互作用的问题,提出一种基于LASSO-OLS(least absolute shrinkage and selection operator-ordinary least squares)的两阶段初始地应力场反演方法。该方法首先通过对候选边界条件应力矩阵和实测应力矩阵进行Frobenius范数标准化处理,消除不同边界条件数据量级差异的影响;然后,利用LASSO回归的L1正则化约束,从候选边界条件的回归系数路径图中筛选关键影响因素,剔除冗余与弱相关项;最后,针对筛选出的核心变量,采用普通最小二乘回归进行无偏估计,构建兼具稀疏性与准确性的地应力场反演模型。研究结果表明:1)在工程应用实例中,借助LASSO回归从11个候选边界条件中筛选出5个关键因素,显著降低模型复杂度;2)模型正则化参数在标准误差内取值,拟合结果能够保持较高的复相关系数(R=0.995 2),表明筛选后的边界条件有效捕捉了初始地应力场特征;3)初始地应力场反演模型通过LASSO回归筛选,在解析多重边界相互作用时表现出较高的稳定性和物理合理性;4)与传统方法相比,该方法能有效避免初始地应力场反演出现过拟合问题,提高反演结果的鲁棒性。
