Journal
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS
Volume 44, Issue 6A, Pages 3706-3711Publisher
JAPAN SOC APPLIED PHYSICS
DOI: 10.1143/JJAP.44.3706
Keywords
organic light-emitting diodes; tris(8-hydroxyquinoline) aluminum(III); solid-state NMR; Al-27 NMR; crystalline polymorphs; amorphous structure; density functional theory
Categories
Ask authors/readers for more resources
The structures of tris(8-hydroxyquinoline) aluminum(III) (Alq(3)) in the different polymorphs, alpha-, gamma-, and delta-Alq(3), and in the amorphous state, amo-Alq(3), have been analyzed by solid-state Al-27 nuclear magnetic resonance (NMR). The local structures of alpha- and amo-Alq(3) 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-Alq(3). In contrast, the isomeric states of gamma- and delta-Alq(3) are facial. The Al-27 NMR spectrum of delta-Alq(3) is influenced by intermolecular interactions, whereas that of gamma-Alq(3) is determined only by a single facial Alq(3) molecule, suggesting that intermolecular interactions are negligible for gamma-Alq(3). This result is closely related to the experimentally observed good solubility of gamma-Alq(3). 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 Alq(3) is a crucial factor for the light-emitting properties.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available