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

Author(s)

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

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 24, n. 22, p. 6-pg., 2022-05-12.

Abstract

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)

• FAPESP's process: 12/11382-9 - Optical modulation of semiconductor nanostructures using surface acoustic waves
• Grantee: Odilon Divino Damasceno Couto Júnior
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 13/22127-2 - Development of novel materials strategic for integrated analytical devices
• Grantee: Lauro Tatsuo Kubota
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/02614-0 - White-emitting silicates doped with lanthanide and transition metal ions for application in warm white-light-emitting diodes
• Grantee: Marian Rosaly Davolos
• Support Opportunities: Regular Research Grants