磁电阻
材料科学
分子间力
凝聚态物理
激发态
电致发光
单重态
磁场
物理
分子
原子物理学
纳米技术
量子力学
图层(电子)
作者
Yue Wu,Zhihua Xu,Bin Hu,Jane Y. Howe
标识
DOI:10.1103/physrevb.75.035214
摘要
We report a tunable magnetoresistance by uniformly mixing strong-spin-orbital-coupling molecule fac-tris (2-phenylpyridinato) iridium $[\mathrm{Ir}(ppy{)}_{3}]$ and weak-spin-orbital-coupling polymer poly($N$-vinyl carbazole) (PVK). Three possible mechanisms, namely charge transport distribution, energy transfer, and intermolecular spin-orbital interaction, are discussed to interpret the $\mathrm{Ir}(ppy{)}_{3}$ concentration-dependent magnetoresistance in the $\mathrm{PVK}+\mathrm{Ir}(ppy{)}_{3}$ composite. The comparison between the magnetic field effects measured from energy-transfer and nonenergy-transfer $\mathrm{Ir}(ppy{)}_{3}$ doped polymer composites indicates that energy transfer and intermolecular spin-orbital interaction lead to rough and fine tuning for the magnetoresistance, respectively. Furthermore, the photocurrent dependence of magnetic field implies that the excited states contribute to the magnetoresistance through dissociation. As a result, the modification of singlet or triplet ratio of excited states through energy transfer and intermolecular spin-orbital interaction form a mechanism to tune the magnetoresistance in organic semiconducting materials.
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