School of Chemical & Biological Engineering, The National Creative Research Initiative Center for Intelligent Hybrids, The WCU Program of Chemical Convergence for Energy & Environment, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.
ACS Nano. 2013 Oct 22;7(10):9019-26. doi: 10.1021/nn403594j. Epub 2013 Sep 24.
We demonstrate bright, efficient, and environmentally benign InP quantum dot (QD)-based light-emitting diodes (QLEDs) through the direct charge carrier injection into QDs and the efficient radiative exciton recombination within QDs. The direct exciton formation within QDs is facilitated by an adoption of a solution-processed, thin conjugated polyelectrolyte layer, which reduces the electron injection barrier between cathode and QDs via vacuum level shift and promotes the charge carrier balance within QDs. The efficient radiative recombination of these excitons is enabled in structurally engineered InP@ZnSeS heterostructured QDs, in which excitons in the InP domain are effectively passivated by thick ZnSeS composition-gradient shells. The resulting QLEDs record 3.46% of external quantum efficiency and 3900 cd m(-2) of maximum brightness, which represent 10-fold increase in device efficiency and 5-fold increase in brightness compared with previous reports. We believe that such a comprehensive scheme in designing device architecture and the structural formulation of QDs provides a reasonable guideline for practical realization of environmentally benign, high-performance QLEDs in the future.
我们通过直接向量子点注入电荷载流子并在量子点内有效进行辐射激子复合，展示了高效、环保的基于磷化铟（InP）量子点（QD）的发光二极管（QLED）。通过采用溶液处理的薄共轭聚合物电解质层，促进了量子点内的直接激子形成，该层通过真空能级移动降低了阴极和量子点之间的电子注入势垒，并促进了量子点内的电荷载流子平衡。在结构工程化的 InP@ZnSeS 异质结构量子点中，这些激子的高效辐射复合得以实现，其中 InP 域中的激子被厚的 ZnSeS 组成梯度壳有效地猝灭。所得 QLED 的外量子效率为 3.46%，最大亮度为 3900 cd/m²，与之前的报道相比，器件效率提高了 10 倍，亮度提高了 5 倍。我们相信，这种设计器件结构和量子点结构配方的综合方案，为未来实际实现环保、高性能 QLED 提供了合理的指导。
