Organic Light-Emitting Diodes Based on Eu(III) Complexes Involving 1,1,1-Trifluoro-4-Phenyl-2,4-Butanedione with Ethanoic and n-Butanoic Acids

Abstract

Organic light-emitting devices (OLEDs) based on novel Eu³⁺ complexes were fabricated and investigated. In the electroluminescence spectrum, characteristic emission of Eu³⁺ is observed; also, an additional wide short-wave band with a maximum at a wavelength of 395 nm and a full width at half-maximum of 60 nm is present. This band is attributed to the contribution of the hole transport layer electroluminescence due to the penetration of charge carriers through the active OLED layer, which leads to electron–hole radiative recombination in PVK. The operating voltage of the OLED was 10 V. Voltage-tunable purplish-white emission was observed for the studied OLEDs, which is confirmed by the chromaticity analysis. The study of the current–voltage characteristics of the manufactured devices showed that they are characterized by two main conduction regimes. The first one (0–7 V) corresponds to a space-charge limited regime; the second one is the trap-limited regime (7–23 V).