Homoleptic platinum(ii ) complexes with pyridyltriazole ligands: excimer-forming phosphorescent emitters for solution-processed OLEDs
| Autor: | Melissa T. Walden, Piotr Pander, J. A. Gareth Williams, Dmitry S. Yufit, Fernando B. Dias |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Doping chemistry.chemical_element 02 engineering and technology General Chemistry Crystal structure 010402 general chemistry 021001 nanoscience & nanotechnology Excimer Photochemistry 01 natural sciences 0104 chemical sciences chemistry.chemical_compound chemistry Excited state Materials Chemistry OLED Homoleptic 0210 nano-technology Phosphorescence Platinum |
| Zdroj: | Journal of materials chemistry C, 2019, Vol.7(22), pp.6592--6606 [Peer Reviewed Journal] |
| ISSN: | 2050-7534 2050-7526 |
| DOI: | 10.1039/c9tc00768g |
| Popis: | Two new homoleptic platinum(II) complexes are reported that feature aryl-appended 5-(2-pyridyl)-1,2,4- triazole chelates acting as N^N ligating ions, PtL1 2 and PtL2 2. Readily prepared from easily accessible proligands, they offer good solubility in organic solvents, allowing them to be incorporated into OLEDs through solution processing. Crystal structures reveal staggered, face-to-face packing of the p systems in adjacent complexes, but with no close PtPt interactions. The complexes display bright unimolecular phosphorescence: for PtL1 2 and PtL2 2 respectively, lmax = 502 and 514 nm; F = 0.21 and 0.48; t = 5.1 and 4.6 ms in deoxygenated CH2Cl2 at 295 K. Both complexes show a strong propensity to form intensely emissive excimers at higher concentrations: lmax = 585 and 625 nm for PtL1 2 and PtL2 2. The photophysical properties in doped and neat thin films have been investigated using steady-state and time-resolved methods. These studies highlight the presence of different environments of bimolecular excited states with different lifetimes, those emitting at lowest energy apparently having the longest lifetimes, contrary to what is normally found for unimolecular emitters through the effects of vibrational deactivation. The prototype solution-processed OLEDs gave EQEs of 9.6–12.5% for PtL1 2 and 8.8–11.4% for PtL2 2, impressive values for solution-processed devices incorporating such simple complexes and only a little inferior to the EQE of 15% achieved using PtL1 2 in a device prepared by evaporation. Compounds of this type have potential to provide the red and green components for white light OLEDs, due to their tunable, uni- and bimolecular excited state emission. |
| Databáze: | OpenAIRE |
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