Highly Efficient Nondoped Green Organic Light-Emitting Diodes with Combination of High Photoluminescence and High Exciton Utilization.
Highly Efficient Nondoped Green Organic Light-Emitting Diodes with Combination of High Photoluminescence and High Exciton Utilization.
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DOI：
10.1021/acsami.5b10129
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发表时间：
2016-01
影响因子：
9.5
通讯作者：
Chu Wang;Xiang-long Li;Yuyu Pan;Shitong Zhang;Liang Yao;Qing Bai;Weijun Li;P. Lu;Bing Yang-Bing-Y
中科院分区：
文献类型：
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作者：
Chu Wang;Xiang-long Li;Yuyu Pan;Shitong Zhang;Liang Yao;Qing Bai;Weijun Li;P. Lu;Bing Yang-Bing-Y
光致发光（PL）效率和激子利用效率是有机电致发光器件（OLED）获得高效电致发光（EL）的两个关键参数。但是将这两种特性（高PL效率和高激子利用率）同时联合收割机结合到荧光材料中并不容易。在这项工作中，一个有效的组合，实现了通过两个概念的杂化本地和电荷转移（CT）状态（HLCT）和“热激子”，其中前者是负责高PL效率，而后者有助于高激子利用率。通过对TPA-BZP（一种绿光给体-受体分子）进行微化学修饰，我们设计合成了CzP-BZP，该化合物具有高的发光效率（η（PL）= 75%）和最大的激子利用效率（η（IQE）= 35%），大大超过了自旋统计极限的25%。CzP-BZP的非掺杂OLED显示出优异的性能：绿色发光，其CIE坐标为（0.34，0.60），最大电流效率为23.99 cd A（-1），最大外量子效率（EQE，η（EQE））为6.95%。这种结合HLCT态和“热激子”的策略应该是设计下一代、低成本、高效率荧光OLED材料的实用方法。
Photoluminescence (PL) efficiency and exciton utilization efficiency are two key parameters to harvest high-efficiency electroluminescence (EL) in organic light-emitting diodes (OLEDs). But it is not easy to simultaneously combine these two characteristics (high PL efficiency and high exciton utilization) into a fluorescent material. In this work, an efficient combination was achieved through two concepts of hybridized local and charge-transfer (CT) state (HLCT) and "hot exciton", in which the former is responsible for high PL efficiency while the latter contributes to high exciton utilization. On the basis of a tiny chemical modification in TPA-BZP, a green-light donor-acceptor molecule, we designed and synthesized CzP-BZP with this efficeient combination of high PL efficiency of η(PL) = 75% in the solid state and maximal exciton utilization efficiency up to 48% (especially, the internal quantum efficiency of η(IQE) = 35% substantially exceed 25% of spin statistics limit) in OLED. The nondoped OLED of CzP-BZP exhibited an excellent performance: a green emission with a CIE coordinate of (0.34, 0.60), a maximum current efficiency of 23.99 cd A(-1), and a maximum external quantum efficiency (EQE, η(EQE)) of 6.95%. This combined HLCT state and "hot exciton" strategy should be a practical way to design next-generation, low-cost, high-efficiency fluorescent OLED materials.