Yellow Emissive Tris(8-hydroxyquinoline) Aluminum by the Incorporation of ZnO Quantum Dots for OLED Applications.

Aya Hekmet Makki,Si-Hyun Park

doi:10.3390/mi12101173

Abstract

Tris(8-hydroxyquinoline) aluminum complexes are of significant interest because of their remarkable optical and electrical properties, both as an emissive layer and electron injection layer. They emit light in the blue and green ranges of the visible spectrum, so for white organic light emitting diodes (OLEDs), yellow emission is required as well. In this study, we propose the use of zinc oxide quantum dots to tune the emission color of the complex while maintaining its luminous efficiency. Hence, tris(8-hydroxyquinoline) aluminum-zinc oxide nanohybrids with different zinc oxide quantum dots concentrations (10, 20, or 30 wt.%) were synthesized. The structural properties were characterized using powder X-ray diffraction analysis, while the composition and optical characteristics were characterized by Fourier transform infrared spectroscopy, UV-visible absorption spectroscopy, and photoluminescence emission spectroscopy. The results show that increased levels of zinc oxide quantum dots lead to a decrease in crystallinity, double hump emission and a slight red shift in emission peaks. Also, at 20 and 30 wt.% of zinc oxide quantum dots concentrations, yellow emission was observed.

Highlights

Organic light-emitting diodes (OLEDs) have attracted significant research attention, especially for next-generation flexible and foldable devices compared with their inorganic counterparts, owing to their outstanding material properties, such as high flexibility, uniform emission over a large area, tunable wavelength, ease of fabrication, low cost and power consumption, and environmental friendliness [1,2,3,4,5]
The distinctive peaks of Alq3 hexagonal nanohybrids studied by X-ray diffraction (XRD)
A yellow emissive Alq3 is obtained through physical means by doping with ZnO quantum dots (QDs)

Summary

Introduction

Organic light-emitting diodes (OLEDs) have attracted significant research attention, especially for next-generation flexible and foldable devices compared with their inorganic counterparts, owing to their outstanding material properties, such as high flexibility, uniform emission over a large area, tunable wavelength, ease of fabrication, low cost and power consumption, and environmental friendliness [1,2,3,4,5]. Throughout the last couple of years, the study has focused on organic-electroluminescent materials. Among those materials, Tris (8-hydroxyquinoline) aluminum (III) (Alq3) has been attracted and seen as a promising candidate for its excellent electrical transport and emission properties, as well as its high thermal stability. Tris (8-hydroxyquinoline) aluminum (III) (Alq3) has been attracted and seen as a promising candidate for its excellent electrical transport and emission properties, as well as its high thermal stability As a result, it is a better choice for emissive and electrontransparent layers in OLED and organic light-emitting transistor (OLET) devices [6,7,8]. Previous studies have shown blue fluorescence in δ- and γ phases while green fluorescence was found in the other phases under UV excitation [9,10,11]

Methods

Results

Conclusion