Abstract

The spin polarization and spin–orbit coupling (SOC) in polymer light emitting diodes (PLEDs) with the active layer doped with Fe3O4 nanoparticles (NPs) were identified through magneto-electroluminescence (MEL). By comparing the MEL characteristics such as linewidth and magnitude between PLEDs with and without Fe3O4 dopant, we confirmed the existence of spin polarization, but ruled out the existence of SOC. Although the spin polarization is positive to electroluminescence, the brightness–current characteristics suggested that the current efficiency of the doped PLED does not improve. We attributed it to the current leakage caused by the Fe3O4 NPs in the active layer. This work is beneficial for us to further understand the effect of magnetic nanoparticle doping on the dynamic behavior of excitons and polaron pairs in organic semiconductor devices.

Highlights

  • Ferrimagnetic nanomaterials are promising materials due to their extensive application potential.[1,2,3,4,5,6]. They have been used in organic electronic devices, like polymer light emitting diodes (PLEDs) and organic solar cells, as anode buffers to improve the injection of holes[7,8,9,10,11] or as an active layer dopant to improve the internal quantum efficiency by adjusting the number ratio of single excitons to triplet excitons (RST).[12,13,14,15]

  • According to the spin polarization model the holes are injected from the anode into the magnetic nanomaterial dispersed in the active layer under a bias voltage, and the holes are spin-polarized by magnetic nanomaterial before they hop onto the host molecule

  • We used MEL ngerprint to identify whether the spin polarization and the spin–orbit coupling (SOC) coexist in Fe3O4-doped PLEDs

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Summary

Introduction

Ferrimagnetic nanomaterials are promising materials due to their extensive application potential.[1,2,3,4,5,6] In recent years, they have been used in organic electronic devices, like polymer light emitting diodes (PLEDs) and organic solar cells, as anode buffers to improve the injection of holes[7,8,9,10,11] or as an active layer dopant to improve the internal quantum efficiency by adjusting the number ratio of single excitons to triplet excitons (RST).[12,13,14,15] Two distinct views have been proposed on the direction of change in the RST. Weiyao Jia, abc Tadaaki Ikoma, c Lixiang Chen,a Hongqiang Zhu, a Xiantong Tang, a Fenlan Qu a and Zuhong Xiong *ab

Results
Conclusion

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