Abstract
A series of solution-processible electroluminescent (EL) Eu3+ complexes were constructed with a self-host strategy, in which neutral ligands were employed as functionalized bidentate phosphine oxide (PO) ligands named DPEPOArn (DPEPO = bis(2-(diphenylphosphino)phenyl) ether oxide). The solubility of these complexes was dramatically improved owing to the increased ratios of organic components. This further enhanced the antenna effect of these ligands in both singlet and triplet energy-transfer processes to support high photoluminescent quantum yields (PLQYs) up to 86% for their Eu3+ complexes, which is outstanding among conjugated Eu3+ complexes. Density function theory (DFT) simulations and electrochemical analysis further verified the contributions of DPEPOArn to the carrier injecting/transporting ability of the complexes. In this sense, these functionalized PO ligands served as hosts in optoelectronic processes, which rendered the self-host feature of their Eu3+ complexes. With the enhanced electrical properties, the spin-coated single-layer organic light-emitting diodes (OLEDs) of these complexes achieved improved low driving voltages, such as onset voltages about 6 V, compared to their Eu3+-contained red-emitting polymeric analogues. [Eu-(DBM)(3)DPEPODPNA(2)] (DBM = 1,3-diphenylpropane-1,3-dione, DPNA = diphenylnaphthylamine) with the most enhanced electrical properties and suitable frontier molecular orbital (FMO) and triplet state locations endowed its devices with the biggest maximum luminance of >90 cd m(-2) and the highest EL efficiencies. This work verified the potential of small molecular EL Eu3+ complexes for solution-processed OLEDs through rational function integrations.
Original language | English |
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Pages (from-to) | 11137-11148 |
Number of pages | 12 |
Journal | Chemistry - A European Journal |
Volume | 20 |
Issue number | 35 |
DOIs | |
Publication status | Published - 25 Aug 2014 |
Keywords
- electrophosphorescence
- europium
- host-guest systems
- optoelectronic properties
- phosphine oxide ligand
- ORGANIC ELECTROLUMINESCENT DEVICES
- EUROPIUM TERNARY COMPLEX
- BETA-DIKETONATE COMPLEX
- 4,5-BIS(DIPHENYLPHOSPHINO)-9,9-DIMETHYLXANTHENE OXIDE
- EFFICIENT ELECTROLUMINESCENCE
- BRIGHT ELECTROLUMINESCENCE
- NONCONJUGATED COPOLYMERS
- EU(III) COMPLEXES
- ENERGY MIGRATION
- UP-CONVERSION