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采用交流阻抗谱技术,研究了以共轭聚合物(poly[2-methoxy,5-(2′-ethylhexoxy)-1,4-phenylenevinylene])(MEH-PPV)为发光层,以带有胺基的聚芴共聚物poly[(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PF-NR2)为电子传输层的发光二极管的交流响应特性.对于结构为ITO/PEDOT/MEH-PPV/PF-NR2/Al的发光器件,交流阻抗谱中出现了负电容效应(negative capacitance),根据对其Cole-Cole图的分析,MEH-PPV/PF-NR2界面的交流响应可用一个RLL并联电路来模拟,实验结果表明,PF-NR2层既是电子传输层同时又充当了空穴阻挡层的作用,并给出了解释这种以PF-NR2/Al为阴极的器件效率提高的微观机理.
In this paper, the effect of poly (2-methoxy, 5- (2’-ethylhexoxy) -1,4-phenylenevinylene] (MEH-PPV) Poly (9,9-bis (3 ’- (N, N-dimethylamino) propyl) -2,7- fluorene) -alt- 2,7- (9,9-dioctylfluorene)] -NR2) is the AC response of the LED in the electron transport layer. For the light emitting device with the structure of ITO / PEDOT / MEH-PPV / PF-NR2 / Al, negative capacitance appears in the AC impedance spectrum, For the Cole-Cole diagram, the AC response of the MEH-PPV / PF-NR2 interface can be modeled by an RLL parallel circuit. The experimental results show that the PF-NR2 layer is both an electron transport layer and a hole blocking layer , And gives a micro-mechanism to explain the efficiency improvement of this PF-NR2 / Al-based device.