Green syntheses of stable and efficient organic dyes for organic hybrid light-emitting diodes
Green syntheses of stable and efficient organic dyes for organic hybrid light-emitting diodes
复制标题
DOI：
10.1039/d1tc01567b
复制
发表时间：
2021-05-13
影响因子：
6.4
通讯作者：
Luscombe, Christine K.
中科院分区：
文献类型：
--
作者：
Huang, Yunping;Cohen, Theodore A.;Luscombe, Christine K.
有机混合发光二极管（混合LED）采用有机染料作为商业蓝色无机LED顶部的光转换器，取代由稀土和/或有毒金属元素合成的现有无机磷光体光转换器，以优化设备的环境可持续性。在这里，我们提出了两种天然衍生的有机染料的混合发光二极管，突出的稳定性和效率提高的基础上，一种新的“受体-受体”的分子设计。这种“受体-受体”骨架包括可可碱和噻二唑，这两个吸电子基团降低能级并抑制光氧化。这将这些染料与广泛采用的“供体-受体”骨架区分开来，其中光氧化通过供电子单元的存在而促进。同时，有机染料上的侧链用于增强溶液的可加工性，这对膜的透明度至关重要，引入了额外的光氧化途径。通过这种“受体-受体”骨架，来自侧链的不稳定性被来自骨架中的电子效应的稳定性增强所抵消。当与工业聚合物聚（苯乙烯-丁二烯-苯乙烯）（SBS）混合时，它们增强的溶解度能够形成高度透明的薄膜，这对于减少LED中的散射损耗至关重要。此外，所得的染料SBS薄膜实现了光致发光量子产率（PLQY）的约90%，在环境条件下。利用它们的透明性和溶液可加工性，我们用这种可可碱-染料-SBS复合物制作了波导，将其纵向组装成无眩光和增强美观的侧光LED器件。
Organic hybrid light-emitting diodes (hybrid-LEDs) employ organic dyes as light converters on top of commercial blue inorganic LEDs, replacing incumbent inorganic phosphor light converters synthesized from rare-earth and/or toxic metallic elements to optimize device environmental sustainability. Here, we present two naturally derived organic dyes for hybrid-LEDs, highlighting stability and efficiency enhancement based on a novel "acceptor-acceptor" molecular design. This "acceptor-acceptor" skeleton comprises theobromine and thiadiazole, two electron-withdrawing groups that lower energy levels and suppress photooxidation. This differentiates these dyes from the widely adopted "donor-acceptor" skeleton, where photooxidation is facilitated by the presence of electron-donating units. Simultaneously, sidechains on organic dyes used to enhance solution processability, crucial for film transparency, introduce an additional photooxidation pathway. With this "acceptor-acceptor" skeleton, the destabilization from sidechains was offset by the stability enhancement from the electronic effects in the backbone. When blended within an industrial polymer, poly(styrene-butadiene-styrene) (SBS), their enhanced solubility enables the formation of highly transparent films, crucial for reducing scattering loss in LEDs. Furthermore, resultant dye-SBS films achieved photoluminescence quantum yields (PLQYs) of around 90% under ambient conditions. Taking advantage of their transparency and solution processability, we fabricated a waveguide with this theobromine-dye-SBS composite, which was subsequentially assembled into an edge-lit LED device of no glare and enhanced aesthetics.