Yasunari Kusaka

Relationships between light-emitting properties and different isomers in polymorphs of tris(8-hydroxyquinoline) aluminum(III) (Alq3) analyzed by solid-state 27Al NMR and density functional theory (DFT) calculations

The structures of tris(8-hydroxyquinoline) aluminum(III) (Alq3) in the different polymorphs, α-, γ-, and δ-Alq3, and in the amorphous state, amo-Alq3, have been analyzed by solid-state 27Al nuclear magnetic resonance (NMR). The local structures of α- and amo-Alq3 are found to be similar; both samples are composed of the meridional isomer and are locally disordered. No evidence of the existence of the facial isomer is found even for amo-Alq3. In contrast, the isomeric states of γ- and δ-Alq3 are facial. The 27Al NMR spectrum of δ-Alq3 is influenced by intermolecular interactions, whereas that of γ-Alq3 is determined only by a single facial Alq3 molecule, suggesting that intermolecular interactions are negligible for γ-Alq3. This result is closely related to the experimentally observed good solubility of γ-Alq3. Density functional theory (DFT) calculations support the identification of the isomeric state and the effect of the intermolecular interactions. A clear correlation between the isomeric state and the fluorescence wavelength is found, indicating that the isomeric state of Alq3 is a crucial factor for the light-emitting properties.

P-51: Novel Positive Type Photosensitive Insulating Materials by Organic/ Inorganic Hybrid Technologies as a Passivation Layer on TFT LCDs

In this paper, we describe a novel positive type photosensitive silica-based spin on glass (SOG) material. This material is made by organic/inorganic hybrid technologies can provide good performances of high insulating resistance, transparency, and heat resistance. This material could be used as a passivation layer on TFT LCDs, and provide a novel vacuum-less process.

Origin of the different emission wavelengths in Alq3 analyzed by solid-state NMR

Tris(8-hydroxyquinoline) aluminum(III) (Alq3) is one of the most widely used materials in organic light-emitting diodes (OLEDs), and the relationship between the structures and the luminescent wavelengths is of recent interest; yellowish-green emissions are observed for the α- and amorphous Alq3, whereas blue emissions are found for the γ- and δ-Alq3. In order to clarify the relationship between the structures and the emission wavelengths, we carried out solid-state nuclear magnetic resonance (NMR) experiments on the different polymorphs of Alq3 and the amorphous state. Based on 27Al and 13C magic angle spinning (MAS) NMR experiments, it is found that the isomeric state of the amorphous Alq3 is the same as that of α-Alq3 and is different from those of γ- and δ-Alq3. Not only for the amorphous, but also for α-Alq3, the local structures are found to be disordered. We also obtained clear evidence that γ-Alq3 is in the facial isomeric state. It is suggested that δ-Alq3 is also facial. The difference between γ- and δ-Alq3 is the intermolecular packing; the effect of intermolecular packing is found only for δ-Alq3. A further confirmation of the isomeric states of these Alq3 samples is obtained from temperature-dependent X-ray diffraction experiments.