Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
Nat Commun. 2014 Dec 18;5:5756. doi: 10.1038/ncomms6756.
Recent developments in the field of π-conjugated polymers have led to considerable improvements in the performance of solution-processed organic light-emitting devices (OLEDs). However, further improving efficiency is still required to compete with other traditional light sources. Here we demonstrate efficient solution-processed multilayer OLEDs using small molecules. On the basis of estimates from a solvent resistance test of small host molecules, we demonstrate that covalent dimerization or trimerization instead of polymerization can afford conventional small host molecules sufficient resistance to alcohols used for processing upper layers. This allows us to construct multilayer OLEDs through subsequent solution-processing steps, achieving record-high power efficiencies of 36, 52 and 34 lm W(-1) at 100 cd m(-2) for solution-processed blue, green and white OLEDs, respectively, with stable electroluminescence spectra under varying current density. We also show that the composition at the resulting interface of solution-processed layers is a critical factor in determining device performance.
近年来，π 共轭聚合物领域的发展使得溶液处理型有机发光器件（OLEDs）的性能得到了显著改善。然而，要与其他传统光源竞争，仍需要进一步提高效率。在这里，我们展示了使用小分子的高效溶液处理多层 OLED。基于对小分子主体分子耐溶剂性测试的估计，我们证明了共价二聚或三聚而不是聚合可以为常规小分子主体分子提供足够的耐醇性，而醇用于处理上层。这使我们能够通过后续的溶液处理步骤构建多层 OLED，实现了溶液处理的蓝色、绿色和白色 OLED 的功率效率分别为 36、52 和 34 lm W(-1)的记录，在不同电流密度下的电致发光光谱稳定。我们还表明，溶液处理层之间的界面组成是决定器件性能的关键因素。
