Organic Electroluminescent Devices Having Derivatives of Aluminum-Hydroxyquinoline Complex as Light Emitting Materials

Abstract

Derivatives of aluminum-hydroxyquinoline complex were synthesized and used as light emitting materials for electroluminescent devices. The absorption and photo-luminescence spectra, and also the energy levels of the derivatives were shifted from those of the mother compound by electron-withdrawing and electron-releasing groups introduced into the hydroxyquinoline ligands. Using these compounds, the relationship between the electroluminescence efficiency and the energy levels was analyzed. The results strongly suggest that part of the injected electrons and holes recombine across the interface of the stacked organic layers, the process being non-emissive. It was also observed that the current-voltage curves shift toward the lower voltages as the electron accepting energy level of the light emitting material becomes lower.

Effective Manipulation of the Electronic Effects and Its Influence on the Emission of 5‐Substituted Tris(8‐quinolinolate) Aluminum(III) Complexes

“…[14] Other attempts at emission tuning failed to yield significant effects or blue-emitting complexes. For example, the introduction of a cyano group at the 5-position of the quinolinolate resulted only in a 4 nm blueshift, [15] whereas the fluoro and chloro [16] substituents yielded, against expectations, Alq 3 complexes with slightly redshifted emissions of l = 535 and 540 nm, respectively.…”

The effect of fluorination on the luminescent behaviour of 8-hydroxyquinoline boron compounds

“…2,3 It is well documented that light emission in AlQ 3 originates from the quinolinol ligand, from a transition between the lowest unoccupied molecular orbital (LUMO) located on the pyridyl ring and the highest occupied molecular orbital (HOMO) on the phenoxide ring. [4][5][6][7] Understandably, one approach to modify AlQ 3 has been to use substituted 8-hydroxyquinolines (8-HQ), [8][9][10][11][12][13][14][15] or different heterocycles such as 5-hydroxyquinoxaline. 7,16 Alterations of this type have resulted in changes of the peak emission wavelength, but often with a loss in luminous efficiency.…”

Performance of Tris(2-methyl-8-quinolinolato)aluminum as Fluorescent Anionophore

“…5 The effects of substituents on the optical performance were studied; [Al(mq)3] was reported to show a blue emission, which was ascribed to an electrondonating methyl group. 6 Later, the mixed-ligand complex with Hmq and phenol (PhOH), [Al(mq)2(OPh)], has been proposed as an alternative having a higher chemical stability. 7,8 To explore the further possibility of the Lewis acid-base reactions for the fluorometric detection of anions, we have studied the reactions of these aluminum complexes ([Al(mq) …”