Exceptionally Fast Radiative Decay of a Dinuclear Platinum Complex Through Thermally Activated Delayed Fluorescence

Pander, Piotr Henryk; Daniels, Ruth; Zaytsev, Andrey; Horn, Ashleigh; Sil, Amit; Penfold, Thomas; Williams, Gareth; Kozhevnikov, Valery Nikolaevich; Dias, Fernando B.

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.

Citation

Pander, P. H., Daniels, R., Zaytsev, A., Horn, A., Sil, A., Penfold, T., Williams, G., Kozhevnikov, V. N., & Dias, F. B. (2021). Exceptionally Fast Radiative Decay of a Dinuclear Platinum Complex Through Thermally Activated Delayed Fluorescence. Chemical Science, 12(17), 6172-6180. https://doi.org/10.1039/d1sc00160d

• Journal Article Type: Article
• Acceptance Date: Mar 19, 2021
• Online Publication Date: Mar 22, 2021
• Publication Date: 2021-05
• Deposit Date: Mar 23, 2021
• Publicly Available Date: Jun 4, 2021
• Journal: Chemical Science
• Print ISSN: 2041-6520
• Electronic ISSN: 2041-6539
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 17
• Pages: 6172-6180
• DOI: https://doi.org/10.1039/d1sc00160d
• Public URL: https://durham-repository.worktribe.com/output/1278575