Novel electroluminescent conjugated polyelectrolytes based on polyfluorene
Novel electroluminescent conjugated polyelectrolytes based on polyfluorene
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DOI：
10.1021/cm034650o
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发表时间：
2004-02-24
影响因子：
8.6
通讯作者：
Cao, Y
中科院分区：
文献类型：
--
作者：
Huang, F;Wu, HB;Cao, Y
交替共聚物聚[(9,9 - 双(3' - (N,N - 二甲基氨基)丙基)-2,7 - 芴)-alt - 2,7(9,9 - 二辛基芴)]（P1）和聚[(9,9 - 双(3' - (N,N - 二甲基氨基)丙基)-2,7 - 芴)-alt - 1,4 - 亚苯基]（P3）通过钯催化的Suzuki偶联反应合成，并且它们的季铵化聚电解质衍生物（P2，P4）通过对末端氨基进行后聚合处理获得。所得的共轭聚电解质（P2，P4）可溶于极性溶剂，如甲醇、N,N - 二甲基甲酰胺（DMF）和二甲基亚砜（DMSO），而P4是一种水溶性的蓝色发光共轭聚电解质。对所得共聚物的电化学和光物理性质进行了充分研究。中性氨基官能化聚芴（P1，P3）和季铵盐官能化共轭聚电解质衍生物（P2，P4）都被用作器件制备中的发光层。所有这些聚合物在使用高功函数金属阴极（如铝）时都比使用低功函数（钡）阴极表现出更高的外量子效率（QE）。对于使用铝阴极的P1、P2、P3和P4，二极管的最大外量子效率分别为0.38%、0.16%、0.07%和0.09%。提出了极性聚合物在聚合物/阴极界面偶极排列的自组装可能机制。我们已经表明，这类聚合物可用作电子注入层，它可以显著提高使用高功函数金属（如铝）的发光聚合物的器件性能。氧化铟锡（ITO）/聚(3,4 - 乙撑二氧噻吩)（PEDT）/聚[2 - 甲氧基 - 5 - (2 - 乙基己氧基) - 1,4 - 苯乙烯撑]（MEHPPV）/P1/铝器件显示出大于2%的外量子效率，与使用钡/铝阴极的效率一样高。
Alternating copolymers poly [(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7(9,9-dioctylfluorene)] (P1) and poly [(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-1,4-phenylene] (P3) were synthesized by the palladium-catalyzed Suzuki coupling reaction and their quaternized ammonium polyelectrolyte derivatives (P2, P4) were obtained through a postpolymerization treatment on the terminal amino groups. The resulting conjugated polyelectrolytes (P2, P4) are soluble in polar solvents such as methanol, DMF, and DMSO while P4 is a water-soluble blue-emitting conjugated polyelectrolyte. The electrochemical and photophysics properties of the resulting copolymers were fully investigated. Both the neutral amino-functionalized polyfluorenes (P1, P3) and the quaternized ammonium salt functional conjugated polyelectrolytes derivatives (P2, P4) were used as the emitting layers in device fabrication. All these polymers show even higher external quantum efficiencies (QE) with the high work-function metal cathode such as Al than with the low work-function (Ba) cathode. The maximal external quantum efficiencies of the diodes are respectively 0.38%, 0.16%, 0.07%, and 0.09% for P1, P2, P3, and P4 with an Al cathode. A possible mechanism of self-assembly of dipole alignment of polar polymer in the polymer/cathode interface was proposed. We have shown that such polymers can be used as an electron-injection layer, which can significantly enhance device performance of light-emitting polymers with high work-function metals such as Al. ITO/PEDT/MEHPPV/P1/Al devices show an external quantum efficiency greater than 2%, as high as that by using a Ba/Al cathode.