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
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
Pure near-infrared(NIR)phosphorescent materials with emission peak larger than 700 nm are of great significance for the development of optoelectronics and biomedicine.We have designed and synthesized two new B-embedde...Pure near-infrared(NIR)phosphorescent materials with emission peak larger than 700 nm are of great significance for the development of optoelectronics and biomedicine.We have designed and synthesized two new B-embedded pure near-infrared(NIR)-emitting iridium complexes(Ir(Bpiq)2acac and Ir(Bpiq)2dpm)with peaks greater than 720 nm.More importantly,they exhibit very narrow phosphorescent emission with full width at half maximum(FWHM)of only about 50 nm(0.12 e V),resulting in a high NIR content(>90%)in their spectrum.In view of better optical property and solubility,the complex Ir(Bpiq)_(2)dpm was used as the emitting layer of a solution-processed OLED device,and achieved good maximum external quantum efficiency(EQE)(2.8%)peaking at 728 nm.This research provides an important strategy for the design of narrowband NIR-emitting phosphorescent iridium complexes and their optoelectronic applications.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.
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。
基金support from the National Natural Science Foundation of China(Nos.22171109,52373195 and 22001097)Natural Science Foundation of Jiangsu Province of China(No.BK20201003)+1 种基金the Postdoctoral Research Foundation of China(No.2021M701657)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(No.JDGD-202301)。
文摘Pure near-infrared(NIR)phosphorescent materials with emission peak larger than 700 nm are of great significance for the development of optoelectronics and biomedicine.We have designed and synthesized two new B-embedded pure near-infrared(NIR)-emitting iridium complexes(Ir(Bpiq)2acac and Ir(Bpiq)2dpm)with peaks greater than 720 nm.More importantly,they exhibit very narrow phosphorescent emission with full width at half maximum(FWHM)of only about 50 nm(0.12 e V),resulting in a high NIR content(>90%)in their spectrum.In view of better optical property and solubility,the complex Ir(Bpiq)_(2)dpm was used as the emitting layer of a solution-processed OLED device,and achieved good maximum external quantum efficiency(EQE)(2.8%)peaking at 728 nm.This research provides an important strategy for the design of narrowband NIR-emitting phosphorescent iridium complexes and their optoelectronic applications.
