Tunneling electron induced molecular electroluminescence from individual porphyrin J-aggregates
Tunneling electron induced molecular electroluminescence from individual porphyrin J-aggregates
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单个卟啉 J 聚集体的隧道电子诱导分子电致发光
DOI：
10.1063/1.4927650
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发表时间：
2015
影响因子：
4
通讯作者：
Dong Zhenchao
中科院分区：
文献类型：
--
作者：
Meng Qiushi;Zhang Chao;Zhang Yang;Zhang Yao;Liao Yuan;Dong Zhenchao
利用超高真空扫描隧道显微镜（STM）研究了单个管状卟啉J-聚集体在Au（111）表面的隧道电子激发下的分子电致发光。高分辨率的STM图像表明一个螺旋管状结构的卟啉J-聚集体与高度有序的“砖”样安排。发现这种聚集的纳米管表现出自解耦的分子结构，并显示出源自离域激子的J聚集体的红移电致发光特性。发现发射峰的位置根据激发位点而略有偏移，这与所观察到的光谱轮廓与电子振动进展的变化一起，表明几个分子内的激子相干数有限。J-聚集体电致发光也被发现是单极的，仅在负样品电压下发生，这可能与通过载流子注入机制的分子激发的背景下的结不对称性有关。
We investigate molecular electroluminescence from individual tubular porphyrin J-aggregates on Au(111) by tunneling electron excitations in an ultrahigh-vacuum scanning tunneling microscope (STM). High-resolution STM images suggest a spiral tubular structure for the porphyrin J-aggregate with highly ordered “brickwork”-like arrangements. Such aggregated nanotube is found to behave like a self-decoupled molecular architecture and shows red-shifted electroluminescence characteristics of J-aggregates originated from the delocalized excitons. The positions of the emission peaks are found to shift slightly depending on the excitation sites, which, together with the changes in the observed spectral profiles with vibronic progressions, suggest a limited exciton coherence number within several molecules. The J-aggregate electroluminescence is also found unipolar, occurring only at negative sample voltages, which is presumably related to the junction asymmetry in the context of molecular excitations via the carrier injection mechanism.