Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

作者：Min Sang Kwon, Youngchang Yu, Caleb Coburn, Andrew W. Phillips, Kyeongwoon Chung, Apoorv Shanker, Jaehun Jung, Gunho Kim, Kevin P. Pipe, Stephen R. Forrest, Ji Ho Youk, Johannes Gierschner, Jinsang Kim · 发表于：Nature Communications · 年份：2015 · DOI：10.1038/ncomms9947 · 被引用次数：452 · 研究领域：Luminescence and Fluorescent Materials、Organic Light-Emitting Diodes Research、Organoboron and organosilicon chemistry

Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin-orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels-Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage.