Carbazole/iridium dendrimer side-chain phosphorescent copolymers for efficient light emitting devices
Carbazole/iridium dendrimer side-chain phosphorescent copolymers for efficient light emitting devices
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DOI：
10.1039/c1nj20493a
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发表时间：
2012-01
影响因子：
3.3
通讯作者：
J. W. Levell;Wenyong Lai;Robert J. Borthwick;P. Burn;S. Lo;I. Samuel
中科院分区：
文献类型：
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作者：
J. W. Levell;Wenyong Lai;Robert J. Borthwick;P. Burn;S. Lo;I. Samuel
树枝状聚合物已被证明是用于可溶液加工的磷光有机发光二极管（OLED）的成功材料。最近，我们一直在研究聚（树枝状大分子）与喷墨打印应用程序的改进粘度。在这项工作中，我们提出了三个磷光侧链共聚物组成的聚（苯乙烯）的骨干，咔唑电荷传输单元，和铱（III）络合物不含树枝状分子（简单的复合物），一个单一的树枝状分子连接到两个配体，或双树枝状的复合物与两个树枝状分子添加到配体。除了它们的电荷传输能力之外，包含咔唑单元的共聚物结构还可以防止发色团的聚集，时间分辨发光中只有一个发射环境就证明了这一点。我们报告了用纯共聚物制成的器件在100 cd m−2和8.3 V下的11.0%（37.3 cd A−1）的高外量子效率。通过将双树枝化共聚物与50wt%的4，4 ′-双（N-二咔唑基）联苯（CBP）共混实现最佳性能，其在100 cd m−2和9.3V下产生14.7%的EQE（48.3 cd A−1）。
Dendrimers have proved to be successful materials for solution-processable phosphorescent organic light emitting diodes (OLEDs). Recently we have been investigating poly(dendrimer)s with improved viscosity for ink-jet printing applications. In this work we present three phosphorescent side-chain copolymers comprised of a poly(styrene) backbone, carbazole charge transporting units, and iridium(III) complexes containing no dendrons (simple complex), a single dendron attached to two of the ligands, or doubly dendronised complexes with two dendrons added to the ligands. In addition to their charge transporting capability the copolymer structure incorporating carbazole units can also prevent aggregation of the chromophores, as evidenced by there being only one emissive environment in time-resolved luminescence. We report high external quantum efficiencies of 11.0% (37.3 cd A−1) at 100 cd m−2 and 8.3 V for devices made with the neat copolymers. The best performance is achieved by blending the doubly dendronised copolymer with 50 wt% of 4,4′-bis(N-dicarbazolyl)biphenyl (CBP) which results in 14.7% EQE (48.3 cd A−1) at 100 cd m−2 and 9.3V.