A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic li...A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.展开更多
在不追加额外的硬件设备投资的前提下,提升直流输电系统的抑制连续换相失败的能力具有重要意义;为此,首先阐述了基于电网换相的直流输电系统换流器换相机理,分析了低压限流启动(VDCOL,voltage dependent current order limiter)的控制方...在不追加额外的硬件设备投资的前提下,提升直流输电系统的抑制连续换相失败的能力具有重要意义;为此,首先阐述了基于电网换相的直流输电系统换流器换相机理,分析了低压限流启动(VDCOL,voltage dependent current order limiter)的控制方法,并根据实时测量的换流母线电压VDCOL的启动电压替代常规的直流电压测量,得到系统故障期间变化缓慢的启动电压;其次基于正常换相机理分析,改变常规VDCOL直流电压与直流电流之间的线性静态恢复关系,将VDCOL常规控制模型替换为变斜率数学模型,再将计算得到的VDCOL启动电压与变斜率VDCOL相结合;最后基于CIGRE HVDC(Conference International des Grands Reseaux Electriques,High-Voltage Direct Current Transmissions)标准测试模型验证了本文提出的控制策略在抑制连续换相失败方面具有明显的有效性与优越性。展开更多
基金the National Natural Science Foundation of China(21871272,91956119 and 21521002)the Youth Innovation Promotion Association CAS(2019034)Qingdao University of Science and Technology(QUSTHX201929)。
文摘A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.
文摘在不追加额外的硬件设备投资的前提下,提升直流输电系统的抑制连续换相失败的能力具有重要意义;为此,首先阐述了基于电网换相的直流输电系统换流器换相机理,分析了低压限流启动(VDCOL,voltage dependent current order limiter)的控制方法,并根据实时测量的换流母线电压VDCOL的启动电压替代常规的直流电压测量,得到系统故障期间变化缓慢的启动电压;其次基于正常换相机理分析,改变常规VDCOL直流电压与直流电流之间的线性静态恢复关系,将VDCOL常规控制模型替换为变斜率数学模型,再将计算得到的VDCOL启动电压与变斜率VDCOL相结合;最后基于CIGRE HVDC(Conference International des Grands Reseaux Electriques,High-Voltage Direct Current Transmissions)标准测试模型验证了本文提出的控制策略在抑制连续换相失败方面具有明显的有效性与优越性。
