Alina Akkuzina

Non-stoichiometry of tris(8-hydroxyquinoline) aluminium: is it possible?

The dependence of the 8-hydroxyquinoline (8-Hq) vapor pressure on temperature, logP8-Hq [Torr] = 8.4249 − 2963.5/T, was experimentally determined in the 386–482 K temperature range using the Bourdon manometer technique. Tris(8-hydroxyquinoline) aluminum (α-Alq3) crystals were synthesized under the 8-Hq controlled partial pressure of 0.1–11.30 Torr. The influence of 8-Hq vapor pressure on the structural and luminescence characteristics of crystalline Alq3 was examined. It was found out that the P8-Hq increase resulted in the changes in the photoluminescence spectra maximum, decay kinetics, and structural characteristics. The unit cell volume of the α-Alq3 crystals decreased from 1141.1 to 1138.7 A3 upon P8-Hq increase.

The influence of synthesis conditions on the stability of tris(8-hydroxyquinoline) aluminum organometallic luminophore

Single-phase crystalline luminophore tris(8-hydroxyquinoline) aluminum (Alq3) has been synthesized at Т = 483 K and a partial pressure of 8-hydroxyquinoline vapor from 0.15 to 6.12 Torr. The influence of P8-Hq on the luminescent characteristics of crystalline Alq3 samples has been studied. It has been found that an increase in P8-Hq led to a shift of the photoluminescence-band maximum and to a change in the photoluminescence-decay kinetics. It has been shown that Alq3 synthesized at Т = 483 K and P8-Hq = 6.12 Torr had the most stable spectral-luminescent characteristics. The results obtained are discussed taking into account defect formation in crystalline Alq3.

To the homogeneity range of tris(8-hydroxyquinoline)gallium

A new technique for the analysis of p8-Hq–T diagrams has been developed for the metal–organic phosphor tris(8-hydroxyquinoline)gallium. The detection of mono- and bivariant equilibria within the p8-Hq–T diagram was done using simultaneous measurements of the photoluminescence and reflection spectra of the condensed phase under controlled p8-Hq pressure and temperature. Using preparations with purity better 99.9988 wt%, the Si-Gaq3Sj-Gaq3V and Si-Gaq3LV equilibria were studied and the corresponding p8-Hq–T diagram was plotted in the 408–665 K temperature range. For the α-Gaq3, it was demonstrated that changing the synthesis conditions within the homogeneity range of the phase resulted in change in the cell volume, chemical activity and electrical properties of crystalline preparation and thin layers deposited due to it.

Synthesis condition influence on stability of metal-organic phosphor based on 8-hydroxyquinoline

Tris(8-hydroxyquinoline) aluminum (Alq₃) powders were synthesized under controlled 8-Hq partial pressure. It was shown that the P_8-Hq increase resulted to changes in the photoluminescence characteristics and the life-time of the Alq₃ phosphor.

Novel hybrid materials based on various oxyquinoline organic phosphour complexes and oxyfluoride glass

Novel luminescent organic-inorganic hybrid materials were synthesized by high temperature reaction between metalorganic phosphors and glass. In the present research we used a lead fluoroborate glass as an inorganic matrix and various luminescent oxyquinoline complexes as organic active agent.

Hybrid nanofilms with laser-control luminescence

Nanosize films of organic electroluminophors have offered the challenge to a new generation of light emitting devices - OLED. Tris-(8-oxyquinoline) aluminum (Alq3) was one of the first compounds which demonstrated high efficient green electroluminescence and to the moment it is still used as emission and electron transport material in OLED. Alq3 is known to exist in several polymorphs with photoluminescence (PL) maximum varied from 537 to 481 nm. One of main problem of OLED technology consists in a high cost of organic materials. An attempt to use organic-inorganic hybrid materials for a creation of a novel thin film emission device has not been very successful yet. But the investigation of hybrid material (HM) based on B2O3 glass matrix and Alq3 as phosphor agent showed that there were observed a significant shift of luminescent peak to short waves after bulk HM annealing. The change in the luminescence spectrum can was explained by the polymorph and/or conformation transitions in Alq3 in the crystal field of the matrix.