Efficient and Long-Living Light-Emitting Electrochemical Cells
| Autor: | Henk J. Bolink, Stefan Graber, Enrique Ortí, Edwin C. Constable, Catherine E. Housecroft, Rubén D. Costa |
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| Rok vydání: | 2010 |
| Předmět: |
Materials science
Quenching (fluorescence) Ligand Stacking Substituent chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Photochemistry 01 natural sciences 0104 chemical sciences Electronic Optical and Magnetic Materials Biomaterials chemistry.chemical_compound chemistry Intramolecular force Electrochemistry Phenyl group Quantum efficiency Iridium 0210 nano-technology |
| Zdroj: | Advanced Functional Materials |
| ISSN: | 1616-301X |
| Popis: | Three new heteroleptic iridium complexes that combine two approaches, one leading to a high stability and the other yielding a high luminescence efficiency, are presented. All complexes contain a phenyl group at the 6-position of the neutral bpy ligand, which holds an additional, increasingly bulky substituent on the 4-position. The phenyl group allows for intramolecular π–π stacking, which renders the complex more stable and yields long-living light-emitting electrochemical cells (LECs). The additional substituent increases the intersite distance between the cations in the film, reducing the quenching of the excitons, and should improve the efficiency of the LECs. Density functional theory calculations indicate that the three complexes have the desired π–π intramolecular interactions between the pendant phenyl ring of the bpy ligand and the phenyl ring of one of the ppy ligands in the ground and the excited states. The photoluminescence quantum efficiency of concentrated films of the complexes improves with the increasing size of the bulky groups indicating that the adopted strategy for improving the efficiency is successful. Indeed, LEC devices employing these complexes as the primary active component show shorter turn-on times, higher efficiencies and luminances, and, surprisingly, also demonstrate longer device stabilities. |
| Databáze: | OpenAIRE |
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