Bispo-Jr AG, Mazali IO, Sigoli FA. Sensitization of lanthanide complexes through direct spin-forbidden singlet → triplet excitation.
Phys Chem Chem Phys 2022;
24:13565-13570. [PMID:
35635090 DOI:
10.1039/d2cp01851a]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
LnIII 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 S0 → T transitions in a series of homobimetallic EuIII, TbIII, ErIII, and YbIII complexes with halogen-substituted benzoate ligands. As halogens and LnIII 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 YbIII 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 LnIII complex luminescence and potential within the energy conversion field.
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