Luminescent osmium (ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells

Daniel A. W. Ross, Paul A. Scattergood, Azin Babaei, Antonio Pertegás, Henk J. Bolink, Paul I. P. Elliott

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The series of osmium(II) complexes [Os(bpy)3−n(btz)n][PF6]2 (bpy = 2,2′-bipyridyl, btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl, 1n = 0, 2n = 1, 3n = 2, 4n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For 4, a dramatic blue-shift relative to the absorption profile for 3 is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(II) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes 2 and 3 display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, 3MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of 1 to 4 are destabilised by between 0.60 and 0.79 eV relative to their Ru(II) analogues. The homoleptic complex 4 appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes 1 to 3 display room temperature luminescent emission and readily reversible Os(II)/(III) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on 2 and 3 show inferior current density and luminance than LECs based on 1, the device utilising 3 shows the highest external quantum efficiency at 0.3%.
Original languageEnglish
Pages (from-to)7748-7757
Number of pages10
JournalDalton Transactions
Volume45
Issue number18
Early online date31 Mar 2016
DOIs
Publication statusPublished - 2016

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Osmium
Ruthenium
Electrochemical cells
2,2'-Dipyridyl
Quantum efficiency
Discrete Fourier transforms
Ground state
Absorption spectra
Luminance
Current density
Display devices
Ligands
Cooling
Infrared radiation
Temperature
acetonitrile
Oxidation-Reduction

Cite this

@article{1ba44060274b4ce29428fb55457b5eeb,
title = "Luminescent osmium (ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells",
abstract = "The series of osmium(II) complexes [Os(bpy)3−n(btz)n][PF6]2 (bpy = 2,2′-bipyridyl, btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl, 1n = 0, 2n = 1, 3n = 2, 4n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For 4, a dramatic blue-shift relative to the absorption profile for 3 is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(II) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes 2 and 3 display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, 3MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of 1 to 4 are destabilised by between 0.60 and 0.79 eV relative to their Ru(II) analogues. The homoleptic complex 4 appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes 1 to 3 display room temperature luminescent emission and readily reversible Os(II)/(III) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on 2 and 3 show inferior current density and luminance than LECs based on 1, the device utilising 3 shows the highest external quantum efficiency at 0.3{\%}.",
author = "Ross, {Daniel A. W.} and Scattergood, {Paul A.} and Azin Babaei and Antonio Perteg{\'a}s and Bolink, {Henk J.} and Elliott, {Paul I. P.}",
note = "Epub and accepted in March 2016 HN 27/10/2017",
year = "2016",
doi = "10.1039/C6DT00830E",
language = "English",
volume = "45",
pages = "7748--7757",
journal = "Dalton Transactions",
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Luminescent osmium (ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells. / Ross, Daniel A. W.; Scattergood, Paul A.; Babaei, Azin; Pertegás, Antonio; Bolink, Henk J.; Elliott, Paul I. P.

In: Dalton Transactions, Vol. 45, No. 18, 2016, p. 7748-7757.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Luminescent osmium (ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells

AU - Ross, Daniel A. W.

AU - Scattergood, Paul A.

AU - Babaei, Azin

AU - Pertegás, Antonio

AU - Bolink, Henk J.

AU - Elliott, Paul I. P.

N1 - Epub and accepted in March 2016 HN 27/10/2017

PY - 2016

Y1 - 2016

N2 - The series of osmium(II) complexes [Os(bpy)3−n(btz)n][PF6]2 (bpy = 2,2′-bipyridyl, btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl, 1n = 0, 2n = 1, 3n = 2, 4n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For 4, a dramatic blue-shift relative to the absorption profile for 3 is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(II) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes 2 and 3 display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, 3MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of 1 to 4 are destabilised by between 0.60 and 0.79 eV relative to their Ru(II) analogues. The homoleptic complex 4 appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes 1 to 3 display room temperature luminescent emission and readily reversible Os(II)/(III) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on 2 and 3 show inferior current density and luminance than LECs based on 1, the device utilising 3 shows the highest external quantum efficiency at 0.3%.

AB - The series of osmium(II) complexes [Os(bpy)3−n(btz)n][PF6]2 (bpy = 2,2′-bipyridyl, btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl, 1n = 0, 2n = 1, 3n = 2, 4n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For 4, a dramatic blue-shift relative to the absorption profile for 3 is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(II) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes 2 and 3 display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, 3MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of 1 to 4 are destabilised by between 0.60 and 0.79 eV relative to their Ru(II) analogues. The homoleptic complex 4 appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes 1 to 3 display room temperature luminescent emission and readily reversible Os(II)/(III) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on 2 and 3 show inferior current density and luminance than LECs based on 1, the device utilising 3 shows the highest external quantum efficiency at 0.3%.

U2 - 10.1039/C6DT00830E

DO - 10.1039/C6DT00830E

M3 - Article

VL - 45

SP - 7748

EP - 7757

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 18

ER -