Fabrication of red organic light emitting diodes (OLEDs) using EuxY(1-x)(TTA)3Phen organic complexes for solid-state lighting

¹Priyadarshini College of Engineering, Nagpur 440010, India

²Department of Physics, R.T.M. Nagpur University, Nagpur 440033, India

³Hung Hee University, Seoul, South Korea

Adv. Mater. Lett., 2012, 2 (1), pp 65-70

DOI: 10.5185/amlett.2010.10169

Publication Date (Web): Apr 08, 2012

Copyright © IAAM-VBRI Press

E-mail: sjdhoble@rediffmail.com

Abstract

The mechanism of energy transfer leading to electroluminescence (EL) of a lanthanide complex, Eu_xY(_1-x)(TTA)₃Phen (TTA= thenoyltrifluoro-acetone, phen=1,10-phenanthroline), doped into TPBi(1,3,5-tris(N-Phenyl-benzimidizol-2-yl) benzene host at 15 wt% of host is investigated. With the device structure of anode/hole transport layer/Eu_xY(_1-x)(TTA)₃Phen (15%): TPBi/electron transport layer/cathode, maximum luminescence of 185.6 cd/m2 and 44.72 cd/m2 was obtained from device I made of Eu_0.4Y_0.6(TTA)₃Phen and device II made of Eu_0.5Y_0.5(TTA)₃Phen, respectively at 18 volts. Saturated red Eu³⁺emission based on ⁵D₀→⁷F₂ transition is centered at a wavelength of 612 nm with a full width at half maximum of 5 nm. From the analysis of I-V, J-V-L characteristics and electroluminescent (EL) spectra, we conclude that direct trapping of holes and electrons and subsequent formation of the excitation occur on the dopant, leading to high quantum efficiencies at low current densities. These results show that fabricated OLED devices can successfully emit saturated red light and can be used in applications such as opto-electronic OLED devices, displays and solid-state lighting technology.

Keywords

Electroluminescence, HOMO, LUMO, OLED device, luminance.