Sensitization of lanthanide complexes through direct spin-forbidden singlet -> triplet excitation

Autor(es)

Bispo-Jr, Airton G. ; Mazali, Italo O. ; Sigoli, Fernando A.

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 24, n. 22, p. 6-pg., 2022-05-12.

Resumo

Ln(III) complexes may display luminescence within the ultraviolet-visible-near-infrared spectral window and although they render bright emissions mainly due to the classical singlet-triplet-state-assisted ligand sensitization, which would be the photophysical parameters if they could be excited through direct spin-forbidden singlet -> triplet transitions? Herein, we report the sensitization of Ln complexes through spin-forbidden S-0 -> T transitions in a series of homobimetallic Eu-III, Tb-III, Er-III, and Yb-III complexes with halogen-substituted benzoate ligands. As halogens and Ln(III) atomic numbers increase, intense singlet -> triplet absorption/excitation bands and relative quantum yields up to 18% were achieved due to an increased spin-orbit coupling effect. Moreover, the near-UV-shifted excitation may enable application in luminescent solar concentrators where Yb-III near-infrared luminescence matches the maximum efficiency of the crystalline Si photovoltaic cell. Therefore, the spin-relaxed excitation channel provides new opportunities to improve the Ln(III) complex luminescence and potential within the energy conversion field. (AU)

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