New Cu(i) halide complexes showing TADF combined with room temperature phosphorescence: The balance tuned by halogens

Andrey Yu Baranov, Alexey S. Berezin, Denis G. Samsonenko, Anton S. Mazur, Peter M. Tolstoy, Viktor F. Plyusnin, Ilya E. Kolesnikov, Alexander V. Artem'Ev

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

A series of Cu(i) halide complexes derived from tris(2-pyridyl)phosphine (Py3P), [Cu2(Py3P)2X2] (X = Cl, Br, I), have been synthesized by a straightforward reaction in solution or through a mechanochemical route. At room temperature, the solid complexes exhibit bright dual-mode photoluminescence (λmax = 520-550 nm, τ = 14.5-20.0 μs, and ΦPL ≈ 53%), expressed by thermally activated delayed fluorescence (TADF) combined with phosphorescence (PH), originating from 1(M + X)LCT and 3(M + X)LCT excited states, respectively. Remarkably, the balance of these radiative processes at 300 K is regulated by halogen atom nature, switching from TADF-assisted phosphorescence to PH-admixed TADF. The emission of [Cu2(Py3P)2Cl2] at 300 K is largely contributed by PH (73%) admixed with the TADF fraction (27%) and [Cu2(Py3P)2Br2] also emits mainly PH (65%) admixed with the larger TADF fraction (35%). Meanwhile, for [Cu2(Py3P)2I2], the TADF channel becomes dominating (61%) and PH contribution drops to 39%. The photophysical study corroborated by (TD)DFT computations has revealed that this effect arises mainly from the narrowing of the ΔE(S1 - T1) gap of the [Cu2(Py3P)2X2] complexes in the order Cl (1500 cm-1) > Br (1250 cm-1) > I (1000 cm-1) which facilitates the TADF pathway and suppresses PH in the same order.

Original languageEnglish
Pages (from-to)3155-3163
Number of pages9
JournalDalton Transactions
Volume49
Issue number10
DOIs
Publication statusPublished - 14 Mar 2020

Keywords

  • ACTIVATED DELAYED FLUORESCENCE
  • LIGHT-EMITTING-DIODES
  • TRIPLET EXCITONS
  • SINGLET
  • EFFICIENCY
  • EMITTERS
  • PYRIDYL

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