8-12 July 2013
Africa/Johannesburg timezone
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The effect of EWG and EDG on the HOMO and LUMO levels of Alq3.

Presented by Ms. Mart-Mari DUVENHAGE on 10 Jul 2013 from 11:10 to 11:30
Type: Oral Presentation
Session: DCMPM2
Track: Track A - Division for Condensed Matter Physics and Materials

Abstract

Tris-(8-hydroxyquinoline) aluminium (Alq3) is used as both the emission and electron transporting layer in organic light emitting diodes (OLEDs). One way to tune the emissive colour of Alq3 is to introduce electron-withdrawing and electron-donating groups (EWG and EDG) onto the hydroxyquinoline ligands. These groups will have an effect on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). In this study Alq3 powders were synthesized with an EDG (-CH3) substituted at position 5 and 7 ((5,7-dimethyl-8-hydroxyquinoline) aluminium) and EWG (-Cl) at position 5 ((5-chloro-8-hydroxyquinoline) aluminium). Absorption and photoluminescence spectra were measured for the different samples and a red shift were observed for both 5,7Me-Alq3 and 5Cl-Alq3. The optical band gap calculated using Tauc’s relation and the absorption data showed that there was a decrease in the bandgap of 0.3 - 0.5 eV. Cyclic voltammetry (CV) were performed on the samples. The HOMO levels of 5,7Me-Alq3 and 5Cl-Alq3 showed a bathochromic shift with respect to Alq3.

Award

Yes

Level

PhD

Supervisor

Prof HC Swart, swarthc@ufs.ac.za, University of the Free State

Paper

yes

Place

Location: A0-60


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