Abnormal magnetic field effects in doped organic light-emitting devices

Deng, Jinqiu; Tang, Xiantong; Pan, Ruiheng; Hu, Yeqian; Zhu, Hong; Xiong, Zuhong; Chen, Xiaoli

doi:10.1360/n972018-00434

Cited by 3 publications

(4 citation statements)

References 11 publications

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“…其中MEL的低磁场快速上升主要归因于磁场抑制的极化子对间ISC [16,17] . MC的低磁场磁场范围快速增大 [32,33] . 而MEL和MC的高磁场缓慢上升来源于TQA散射过程 [18] , 其详细的解 MEL (25 mT) 和MC LFE = MC (300 mT) − MC (25 mT) [33] .…”

Section: 在有机发光器件中unclassified

Exciton regulation mechanism of Alq3/HAT-CN tandem electroluminescent devices

Li,

Guan,

Bao

et al. 2023

Acta Phys. Sin.

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Tandem organic electroluminescent devices (OLEDs) have attracted widespread attention due to their long lifetime and high current efficiency. In this study, a double-emitting unit tandem OLED was fabricated using Alq3/HAT-CN as an interconnect layer. Its photovoltaic properties and exciton regulation mechanism were investigated. The results show that the luminance (11189.86 cd/m2) and efficiency (13.85 cd/A) of the tandem OLED reached 2.7 times that of the single EL unit OLED (luminance and efficiency of 4007.14 cd/m2 and 5.00 cd/A, respectively) at a current density of 80 mA/cm2. This proves that Alq3/HAT-CN is an efficient interconnect layer. At room temperature, the polaron pair undergoes intersystem crossing (ISC) due to hyperfine interaction (HFI) when a magnetic field is applied to the device. This increases the concentration of the triplet exciton (T1), which favours charg the scattering. The result is a rapid increase in the low magnetic field and a slow increase in the high magnetic field of the MEL. When the injection current strength is constant, there is less uncompounded charge in the Alq3/HAT-CN device than in other connected layer devices. Triplet-charge annihilation (TQA) is weak, resulting in a relative increase in the concentration of T1, which is not involved in TQA. This suppresses the ISC and leads to a minimal increase in the MEL. As the current strength increases, the T1 concentration increases, causing TQA toincrease and ISC to decrease. Since TQA is related to charge and T1 concentration, lowering the temperature decreases the carrier mobility in the device, resulting in a relative decrease in charge concentration and a weakening of TQA. Lowering the temperature decreases the quenching of thermal phonons and increases the concentration of T1 while extending its lifetime, resulting in enhanced triplet-triplet annihilation (TTA). At low temperatures, the high magnetic field shape of the MEL changes from slowly increasing to rapidly decrease. Therefore, the concentration of T1 can be regulated by varying the current strength and temperature, which further affects the strength of ISC, TQA and TTA, and the luminescence and efficiency of the device can be effectively improved by reducing TQA and ISC. This work is important for the understanding of the luminescence mechanism of small molecule tandem devices and investigating the investigation of the mechanism for improving their photovoltaic performance.

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Section: 在有机发光器件中unclassified

Exciton regulation mechanism of Alq3/HAT-CN tandem electroluminescent devices

Li,

Guan,

Bao

et al. 2023

Acta Phys. Sin.

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“…Peng等人 [14] [18] . [19,20] , RISC [7,21] , TTA [2,22] 和TQA [9,23] )对应的MEL特征线型 [26] )与客体DCJTB的三重态能量 http://engine.scichina.com/doi/10.1360/N972018-01101 CBP的三线态能级为2.66 eV [27] , 远大于DCJTB的三线态激子能量(1.974 eV), 确保了客体DCJTB中 3 CT 激子的寿命较长, 为RISC过程的发生提供了有利的条件. 通常来说, 为了实现RISC, 激子的寿命必须要大于电子自旋发生翻转的时间(10 −9 s) [28] .…”

Section: 使其成为目前主流的Risc体系unclassified

“…对于非紧束缚的电荷转移态材料DCJTB来说, 它们的载流子之间的库伦吸引力较弱, 内电场对三重态激子的拆分作用不能忽视 [13] . 器件内电场会随着电流增大 [23] . 因此我们认为, 当温度降低时, 器件 B和C高场的变化(如图4…”

Section: 使其成为目前主流的Risc体系unclassified

Understanding the mechanisms of light emission from DCJTB charge-transfer states in OLEDs using organic magnetic field effects

Xu¹,

Tang²,

Deng³

et al. 2019

Chin. Sci. Bull.

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“…有机发光二极管(Organic Light-Emitting Diode, OLED)具有易制作、化学可调、透明、易弯曲等特点 [1][2][3][4][5][6][7][8] . OLED中存在很多与激子相关的演化过程, 如系间窜越(Intersystem Crossing, ISC) [9] 、单重态激子分裂(Singlet Fission, STT) [10] 、三重态激子湮灭(Triplet Fusion, TTA) [11] 等.…”

Section: 引言unclassified

Using magneto-electroluminescence to analyze the influence of high temperature environment on exciton evolution processes in organic light-emitting diodes

Zhu

Chen

Huo

2019

Sci. Sin.-Phys. Mech. Astron.

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Abnormal magnetic field effects in doped organic light-emitting devices

Cited by 3 publications

References 11 publications

Exciton regulation mechanism of Alq<sub>3</sub>/HAT-CN tandem electroluminescent devices

Exciton regulation mechanism of Alq<sub>3</sub>/HAT-CN tandem electroluminescent devices

Understanding the mechanisms of light emission from DCJTB charge-transfer states in OLEDs using organic magnetic field effects

Using magneto-electroluminescence to analyze the influence of high temperature environment on exciton evolution processes in organic light-emitting diodes

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