Wide-bite-angle disphosphine ligands in thermally activated delayed fluorescent copper(I) complexes: impact on the performance of electroluminescence applications

Chenfei Li, Campbell Frank Ross Mackenzie, Said A. Said, Amlan Kumar Pal, Mohammed A. Haghighatbin, Azin Babaei, Michele Sessolo, David Bradford Cordes, Alexandra Martha Zoya Slawin, Paul C J Kamer, Henk Bolink, Conor F. Hogan, Eli Zysman-Colman

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Abstract

We report a series of seven cationic heteroleptic copper(I) complexes of the form [Cu(P^P)(dmphen)]BF4, where dmphen is 2,9-dimethyl-1,10-phenanthroline and P^P is a diphosphine chelate, in which the effect of the bite angle of the diphosphine ligand on the photophysical properties of the complexes was studied. Several of the complexes exhibit moderately high photoluminescence quantum yields in the solid state, with ΦPL of up to 35%, and in solution, with ΦPL of up to 98%. We were able to correlate the powder photoluminescence quantum yields with the % Vbur of the P^P ligand. The most emissive complexes were used to fabricate both organic light-emitting diodes and light-emitting electrochemical cells (LECs), both of which showed moderate performance. Compared to the benchmark copper(I)-based LECs, [Cu(dnbp)(DPEPhos)]+ (maximum external quantum efficiency, EQEmax = 16%), complex 3 (EQEmax = 1.85%) showed a much longer device lifetime (t1/2 = 1.25 h and >16.5 h for [Cu(dnbp)(DPEPhos)]+ and complex 3, respectively). The electrochemiluminescence (ECL) properties of several complexes were also studied, which, to the best of our knowledge, constitutes the first ECL study for heteroleptic copper(I) complexes. Notably, complexes exhibiting more reversible electrochemistry were associated with higher annihilation ECL as well as better performance in a LEC.
Original languageEnglish
Number of pages17
JournalInorganic Chemistry
VolumeArticles ASAP
Early online date1 Jul 2021
DOIs
Publication statusE-pub ahead of print - 1 Jul 2021

Keywords

  • Redox reactions
  • Ligands
  • Crystal structure
  • Organophosphorus compounds
  • Nuclear magnetic resonance spectroscopy

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