Efficient solution‐processed double‐layer red OLEDs based on a new europium complex with a carbazole group

Abstract

A new europium complex EuL3 (Phen) was used as guest dopant, and a blend of Polyvinylcarbazole and 2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PVK and PBD) as host matrix. Efficient red organic light-emitting devices (OLEDs) with double-layer structures were manufactured via a solution-processed technique. The guest-doped levels were 1, 3 and 5 wt% relative to the blend mass, respectively. For the 1 wt% doping-level device, the luminous efficiency and luminance were up to 2.96 cd/A and 635.78 cd/m(2) with emissions from both EuL3 (Phen) and from the host; for the 3 wt% doping-level device, the maximum luminous efficiency and luminance were 1.01 cd/A and 370.91 cd/m(2) for the single emission from EuL3 (Phen) only.

Eu(III) Complexes for LEDs Based on Carbazole- and Fluorene-Functionalized Phenanthro-Imidazole Ancillary Ligands: Detailed Photophysical and Theoretical Study

“…In the current study, CBZ and Phen based consequences were made by using 2‐thenoyltrifluoroacetone (TTA) as an antenna named were Eu(TTA) 3 Phen‐Fl‐CBZ (1Eu) and Eu(TTA) 3 Phen‐Fl‐CBZ‐t‐But (2Eu) with novel bipolar ligands Phen‐Fl‐CBZ (2‐(4‐(9H‐carbazol‐9‐yl)phenyl)‐1‐(9,9‐diethyl‐9H‐fluoren‐2‐yl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline, 1 L) and Phen‐Fl‐CBZ‐t‐But (2‐(4‐(3,6‐di‐tert‐butyl‐9H‐carbazol‐9‐yl)phenyl)‐1‐(9,9‐diethyl‐9H‐fluoren‐2‐yl)‐1H‐imidazo[4,5 f][1,10]phenanthroline, 2 L). The inclusion of the bulky t‐butyl groups expecting to reduce self‐quenching and phase separation in the device, it leads to the longer life time operations . TTA acts as efficient energy transfer to Eu(III) central metal ion and it may increase the decay time by decrease the vibrational quenching.…”

Mixed-Lanthanide Metal–Organic Frameworks with Tunable Color and White Light Emission

“…Lanthanide remains attractive due to their highly monochromatic emissions arising from 4f n → 4f n transitions, − which make them popular materials with application in display devices that focus on full-color display mainly consisting of white and tunable pure color emitters. Traditionally, most color-tunable materials are mixtures generated typically by mixing different color emitting materials together. − An alternative approach is making couples of chromophores emit simultaneously in a single-component backbone, − which has a significant improvement in stability, reproduction, and fabrication process compared to the traditional way. Lanthanide metal–organic frameworks (Ln-MOFs) are definitely the promising backbones, since different lanthanide chromophores can be controllably incorporated, leading to generate emitters in the whole visible region.…”

Excellent Electroluminescent Property of Eu3+-Induced Polystyrene-co-poly(acrylic acid) Aggregates (EIPAs) in Polymeric Light-Emitting Diodes

“…As the doping concentration increases from 3 to 5 wt % and then to 10 wt %, the films become much rougher and the RMS roughness increases from 0.413 to 0.534 nm and then to 0.897 nm. Since the higher doping concentration of EIPA1 leads to increased surface roughness and larger-scale phase separation, these conditions lengthen charge transfer paths and reduce the diffusion rate, which is detrimental to efficient charge transfer and ultimately makes the device performance worse. , In summary, 3 wt % doping is preferable to improve the device performance and charge transfer.…”