Abstract
Colorless and transparent emission materials are being rapidly developed in view of their potential for use in emission devices, ornaments, and other applications. We focused on rare-earth complexes because of their transparency when dissolved in polymer and pure color emission. The first concept of novel molecular design of rare-earth complexes, namely, introduction of two different phosphine oxides into one rare-earth ion as ligands, was established, and their solubility and emission intensity were drastically enhanced. The second concept is that two different phosphine oxides are tied together and asymmetric bis-phosphine oxide structure is introduced to one rare-earth ion. The emission intensity of an Eu(III) complex was further enhanced. Colorless and transparent emission materials using novel rare-earth complexes have excellent transparency and strong pure color emission, and are promising candidates for a variety of application fields, including emission devices, where the see-through feature will be essential.
