有机发光二极管(OLEDs)中电致发光磁效应(MEL)是一种能够揭示多种激发态微观过程的探测工具.最新研究成果(Tang X T,Pan R H,Zhao X,Jia W Y,Wang Y,Ma C H 2020 Adv.Funct.Mater.5765)表明:将低浓度的红荧烯(Rubrene)分子掺杂在一定主...有机发光二极管(OLEDs)中电致发光磁效应(MEL)是一种能够揭示多种激发态微观过程的探测工具.最新研究成果(Tang X T,Pan R H,Zhao X,Jia W Y,Wang Y,Ma C H 2020 Adv.Funct.Mater.5765)表明:将低浓度的红荧烯(Rubrene)分子掺杂在一定主体作为发光层的OLEDs中,存在一种高能三重态激子(T_(2,Rub))的反向系间窜越过程(HL-RISC,S_(1,Rub)←T_(2,Rub)).但本文发现:以Rubrene作为纯发光层且其两边的载流子传输层也不存在T_(2,Rub)激子的能量损失通道的OLEDs中,在室温下只观察到单重态激子(S_(1))的分裂过程(S_(1)+S_(0)→T_(1)+T_(1)),却没能观察到该T_(2,Rub)激子的HL-RISC过程;而且,最基本的因电子和空穴在纯Rubrene发光层中直接注入形成极化子对(polaron-pair,PP_(1)和PP_(3))的系间窜越过程(ISC,PP_(1)→PP_(3))也没有被观察到.为了揭示该反常现象背后的微观物理机制,以纯Rubrene分子和质量分数为5%的Rubrene掺杂主体作为发光层来制备器件,并对两种器件的MEL进行变温实验.对所得实验结果比对分析后发现:室温下PP态的ISC和T_(2,Rub)激子的HL-RISC产生的MEL正好完全相互抵消,这是采用MEL在纯Rubrene作为发光层的OLEDs中同时观察不到ISC和HL-RISC的物理原因,这种如此巧合的物理现象在文献中还未曾报道.展开更多
The ceramic samples with nominal composition of La_(2/3)Ca_(1/3)Fe_(1-x)Mn_(x)O_(3)(0.01≤x≤0.20)were prepared by solid state reaction method.The effect of Fe doping on the Mn site was measured by the positron annihi...The ceramic samples with nominal composition of La_(2/3)Ca_(1/3)Fe_(1-x)Mn_(x)O_(3)(0.01≤x≤0.20)were prepared by solid state reaction method.The effect of Fe doping on the Mn site was measured by the positron annihilation technique and M'dssbauer spectroscopy.Upon doping,no appreciable structure change and electronic structure change in Mn-O plane were observed in the series of compounds.The M6ssbauer parameters show that the iron probe has stable 3+valance with the high spin state in all samples.Moreover,by examining the shape of the spectra,the tendency can be found that the isomer shift and quadruploe splitting increase with the increasing Fe+3 content.This phenomenon shows the local lattice distortion and the localization of d-electrons with the increasing Fe-doping content.展开更多
文摘有机发光二极管(OLEDs)中电致发光磁效应(MEL)是一种能够揭示多种激发态微观过程的探测工具.最新研究成果(Tang X T,Pan R H,Zhao X,Jia W Y,Wang Y,Ma C H 2020 Adv.Funct.Mater.5765)表明:将低浓度的红荧烯(Rubrene)分子掺杂在一定主体作为发光层的OLEDs中,存在一种高能三重态激子(T_(2,Rub))的反向系间窜越过程(HL-RISC,S_(1,Rub)←T_(2,Rub)).但本文发现:以Rubrene作为纯发光层且其两边的载流子传输层也不存在T_(2,Rub)激子的能量损失通道的OLEDs中,在室温下只观察到单重态激子(S_(1))的分裂过程(S_(1)+S_(0)→T_(1)+T_(1)),却没能观察到该T_(2,Rub)激子的HL-RISC过程;而且,最基本的因电子和空穴在纯Rubrene发光层中直接注入形成极化子对(polaron-pair,PP_(1)和PP_(3))的系间窜越过程(ISC,PP_(1)→PP_(3))也没有被观察到.为了揭示该反常现象背后的微观物理机制,以纯Rubrene分子和质量分数为5%的Rubrene掺杂主体作为发光层来制备器件,并对两种器件的MEL进行变温实验.对所得实验结果比对分析后发现:室温下PP态的ISC和T_(2,Rub)激子的HL-RISC产生的MEL正好完全相互抵消,这是采用MEL在纯Rubrene作为发光层的OLEDs中同时观察不到ISC和HL-RISC的物理原因,这种如此巧合的物理现象在文献中还未曾报道.
基金Supported by the National Natural Science Foundation of China under Grant No.19805010by the Key-project of Chinese Academy of Sciences under contract KJ952-S1-416.
文摘The ceramic samples with nominal composition of La_(2/3)Ca_(1/3)Fe_(1-x)Mn_(x)O_(3)(0.01≤x≤0.20)were prepared by solid state reaction method.The effect of Fe doping on the Mn site was measured by the positron annihilation technique and M'dssbauer spectroscopy.Upon doping,no appreciable structure change and electronic structure change in Mn-O plane were observed in the series of compounds.The M6ssbauer parameters show that the iron probe has stable 3+valance with the high spin state in all samples.Moreover,by examining the shape of the spectra,the tendency can be found that the isomer shift and quadruploe splitting increase with the increasing Fe+3 content.This phenomenon shows the local lattice distortion and the localization of d-electrons with the increasing Fe-doping content.
