Exceptionally fast radiative decay of a dinuclear platinum complex through thermally activated delayed fluorescence

Piotr Pander*, Ruth Daniels, Andrey Zaytsev, Ashleigh Horn, Amit Sil, Thomas J. Penfold, J. A. Gareth Williams, Valery Kozhevnikov, Fernando B. Dias

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
17 Downloads (Pure)

Abstract

A novel dinuclear platinum(II) complex featuring a ditopic, bis-tetradentate ligand has been prepared. The ligand offers each metal ion a planar O^N^C^N coordination environment, with the two metal ions bound to the nitrogen atoms of a bridging pyrimidine unit. The complex is brightly luminescent in the red region of the spectrum with a photoluminescence quantum yield of 83% in deoxygenated methylcyclohexane solution at ambient temperature, and shows a remarkably short excited state lifetime of 2.1 μs. These properties are the result of an unusually high radiative rate constant of around 4 × 105 s−1, a value which is comparable to that of the very best performing Ir(III) complexes. This unusual behaviour is the result of efficient thermally activated reverse intersystem crossing, promoted by a small singlet–triplet energy difference of only 69 ± 3 meV. The complex was incorporated into solution-processed OLEDs achieving EQEmax = 7.4%. We believe this to be the first fully evidenced report of a Pt(II) complex showing thermally activated delayed fluorescence (TADF) at room temperature, and indeed of a Pt(II)-based delayed fluorescence emitter to be incorporated into an OLED.
Original languageEnglish
Pages (from-to)6172-6180
Number of pages9
JournalChemical Science
Volume12
Issue number17
Early online date22 Mar 2021
DOIs
Publication statusPublished - 7 May 2021

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