Ruthenium(II) Polyimine Complexes with a Long‐Lived 3IL Excited State or a 3MLCT/3IL Equilibrium: Efficient Triplet Sensitizers for Low‐Power Upconversion

Up, up, and away! The long-lived 3IL excited states of RuII polyimine complexes were found to be more efficient in sensitizing upconversion based on triplet–triplet annihilation (TTA) and energy transfer (TTET) than the shorter-lived 3MLCT excited states (see picture). Upconversion occurs with an anti-Stokes shift of up to 0.77 eV. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.