Effect of ZnO nanoparticle on morphology and optical properties of yellow emissive bulk Alq3 for OLED application

• Published in: Optical materials Vol. 154; p. 115768
• Main Authors: Debsharma, Mrinmoy, Pramanik, Tanay, Maji, Partha Sona, Maity, Amit Ranjan, Jain, Alok, Mukherjee, Rupam
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2024
• Subjects: Band gap; Fillers; Morphology; Nano composites; Optical properties; Nano composites; Band gap; Morphology; Optical properties; Fillers
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2024.115768

We observe a distinct blue shift of the electronic absorption band in a composite nanoparticle system consisting of wide band gap semiconductor ZnO grains embedded into tris(8-hydroxyquinolinato)aluminium (Alq3) matrix and calcined at 50 °C. This is followed by successive red shifts of absorbance intensity when weight percentage of ZnO NPs in ZnO/Alq3 nano-composite is varied from 0.1 to 0.4 wt %. To investigate the morphology and optical properties, we prepared coordination complex Alq3 by using wet synthesis method, with the absorption peak found to be at 358 nm in room temperature. For 0.1 wt% ZnO:Alq3 composite, it exhibits lower energy band gap of 2.85 eV as compared to wide band gap ZnO nanoparticle (3.37 eV) and as-prepared bulk Alq3 (2.89 eV). On illuminating with excitation wavelength of 385 nm, as-prepared Alq3 shows a fluorescence band peak at around 520 nm but with the increasing concentration of ZnO nanoparticles, it exhibits broad peaks which are found to be shifted to higher wavelengths. The composites show yellow colored emission at 548.7 nm wavelength which is an essential requisite condition for white colored OLEDs. Further, XRD, FESEM confirm the rod shaped ZnO nanoparticle get embedded and agglomerated onto Alq3 surface resulting in the increase in structural volume (662.8 c. c.) compared to that of individual constituents 47.6 c. c. For ZnO and 386.72 c. c. For Alq3 powder. Experimental analysis suggests that incorporation of ZnO filler into Alq3 matrix offers a significant improvement in the optical & structural properties as compared to pristine Alq3, thus opening a room for futuristic OLED applications. •Synthesis of ZnO Nano-particle, Alq3 (Tris (8-hydroxyquinoline)aluminium) powder and ZnO/Alq3 Nanocomposites.•We variate concentration of ZnO NP filler into Alq3 powder and produced ZnO/Alq3 Nano-composites.•We studied structural, optical properties of each constituent individually.•For ZnO:Alq3 composites, it exhibit lower energy band gap of 2.738 eV as compared to wide band gap ZnO nanoparticle (3.37 eV) and as-prepared bulk Alq3 (3.26eV).•XRD, FESEM and EDAX confirms the rod shaped ZnO nanoparticle get embedded and agglomerated onto Alq3 surface. The composites show yellow colored emission at 544.8 nm wavelength which is an essential requisite condition for white colored OLED.