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Article: Highly luminescent palladium(ii) complexes with sub-millisecond blue to green phosphorescent excited states. Photocatalysis and highly efficient PSF-OLEDs

TitleHighly luminescent palladium(ii) complexes with sub-millisecond blue to green phosphorescent excited states. Photocatalysis and highly efficient PSF-OLEDs
Authors
Issue Date2016
PublisherRoyal Society of Chemistry.
Citation
Chemical Science, 2016, v. 7 n. 9, p. 6083-6098 How to Cite?
AbstractPalladium(II) complexes supported by tetradentate [N^C^C^N] and [O^N^C^N] ligand systems display sky blue to red phosphorescence with emission quantum yields and emission lifetimes up to 0.64 and 272 μs, respectively. Femtosecond time-resolved fluorescence (fs-TRF) measurements on these Pd(II) complexes reveal a fast intersystem crossing from singlet to triplet manifolds with time constants of 0.6–21 ps. DFT/TDDFT calculations revealed that, as a result of the spiro-fluorene and bridging tertiary amine units of the ligands, the T1 excited state is more ligand-localized and has smaller structural distortion, leading to slower non-radiative decay as well as radiative decay of T1 → S0 transition and thereby highly emissive, long-lived triplet excited states. The Pd(II) complexes have been found to be efficient catalysts for visible light-driven, reductive C–C bond formation from unactivated alkyl bromides with conversions and yields of up to 90% and 83%, respectively. These complexes have also been employed as photosensitizers for [2 + 2] cycloaddition of styrenes, with conversions and yields comparable to those of the reported Ir(III) complexes. Both green and sky blue organic-light emitting devices (OLEDs) have been generated with these Pd(II) complexes as guest emitters. Maximum external quantum efficiencies (EQE) of up to 16.5% have been achieved in the sky blue OLEDs. The long emission lifetimes render the Pd(II) complexes good sensitizers for phosphor-sensitized fluorescent OLEDs (PSF-OLEDs). By utilizing these phosphorescent Pd(II) complexes as sensitizers, highly efficient green and yellow PSF-OLEDs having high EQE (up to 14.3%), high colour purity and long operation lifetimes, with 90% of initial luminance (LT90) for more than 80 000 h, have been realized.
Persistent Identifierhttp://hdl.handle.net/10722/234495
ISSN
2019 Impact Factor: 9.346
2015 SCImago Journal Rankings: 4.974
PubMed Central ID
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorChow, PK-
dc.contributor.authorCheng, G-
dc.contributor.authorTong, GSM-
dc.contributor.authorMa, C-
dc.contributor.authorKwok, WM-
dc.contributor.authorAng, WH-
dc.contributor.authorChung, CYS-
dc.contributor.authorYang, C-
dc.contributor.authorWang, F-
dc.contributor.authorChe, CM-
dc.date.accessioned2016-10-14T13:47:15Z-
dc.date.available2016-10-14T13:47:15Z-
dc.date.issued2016-
dc.identifier.citationChemical Science, 2016, v. 7 n. 9, p. 6083-6098-
dc.identifier.issn2041-6520-
dc.identifier.urihttp://hdl.handle.net/10722/234495-
dc.description.abstractPalladium(II) complexes supported by tetradentate [N^C^C^N] and [O^N^C^N] ligand systems display sky blue to red phosphorescence with emission quantum yields and emission lifetimes up to 0.64 and 272 μs, respectively. Femtosecond time-resolved fluorescence (fs-TRF) measurements on these Pd(II) complexes reveal a fast intersystem crossing from singlet to triplet manifolds with time constants of 0.6–21 ps. DFT/TDDFT calculations revealed that, as a result of the spiro-fluorene and bridging tertiary amine units of the ligands, the T1 excited state is more ligand-localized and has smaller structural distortion, leading to slower non-radiative decay as well as radiative decay of T1 → S0 transition and thereby highly emissive, long-lived triplet excited states. The Pd(II) complexes have been found to be efficient catalysts for visible light-driven, reductive C–C bond formation from unactivated alkyl bromides with conversions and yields of up to 90% and 83%, respectively. These complexes have also been employed as photosensitizers for [2 + 2] cycloaddition of styrenes, with conversions and yields comparable to those of the reported Ir(III) complexes. Both green and sky blue organic-light emitting devices (OLEDs) have been generated with these Pd(II) complexes as guest emitters. Maximum external quantum efficiencies (EQE) of up to 16.5% have been achieved in the sky blue OLEDs. The long emission lifetimes render the Pd(II) complexes good sensitizers for phosphor-sensitized fluorescent OLEDs (PSF-OLEDs). By utilizing these phosphorescent Pd(II) complexes as sensitizers, highly efficient green and yellow PSF-OLEDs having high EQE (up to 14.3%), high colour purity and long operation lifetimes, with 90% of initial luminance (LT90) for more than 80 000 h, have been realized.-
dc.languageeng-
dc.publisherRoyal Society of Chemistry.-
dc.relation.ispartofChemical Science-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.titleHighly luminescent palladium(ii) complexes with sub-millisecond blue to green phosphorescent excited states. Photocatalysis and highly efficient PSF-OLEDs-
dc.typeArticle-
dc.identifier.emailCheng, G: ggcheng@hku.hk-
dc.identifier.emailTong, GSM: tongsm@hku.hk-
dc.identifier.emailChung, CYS: cyschung@hku.hk-
dc.identifier.emailWang, F: wf2013@hku.hk-
dc.identifier.emailChe, CM: chemhead@hku.hk-
dc.identifier.authorityCheng, G=rp02145-
dc.identifier.authorityTong, GSM=rp00790-
dc.identifier.authorityChung, CYS=rp02672-
dc.identifier.authorityChe, CM=rp00670-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1039/C6SC00462H-
dc.identifier.pmid30034749-
dc.identifier.pmcidPMC6024183-
dc.identifier.scopuseid_2-s2.0-84983518040-
dc.identifier.hkuros268313-
dc.identifier.volume7-
dc.identifier.issue9-
dc.identifier.spage6083-
dc.identifier.epage6098-
dc.identifier.isiWOS:000382488500058-
dc.publisher.placeUnited Kingdom-

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