{
  "abstract": "Our work presents three new di-iridium(III) complexes Ir-H, Ir-F, and Ir-CN displaying strong thermally activated delayed fluorescence (TADF) behaviour. These complexes were obtained by variating the group R = H, F, CN at the 5-position on the pyrimidine-based bridging ligand. Our Ir(III) complexes emit green to orange photoluminescence in polystyrene film, with λPL in the range from 529 nm for Ir-H to 583 nm for Ir-CN and with unity photoluminescence quantum yield. They display clear negative solvatochromism in solution, in line with the metal-to-ligand charge-transfer (MLCT) nature of their excited states. Their TADF performance has been established in a temperature-dependent experiment with the ΔE S-T ranging 30-46 meV with the lowest value reported for orange emitter Ir-CN. Our work is complemented with a detailed computational study and modelling. We report the record high solution-processed organic light-emitting diode (OLED) external quantum efficiency (EQE) of 19.5% recorded for emitter Ir-F at luminance of 1000 cd m -2 . This remarkable achievement presents the highest EQE figure for any iridium(III) complex for which TADF has been reported and double the previous record. The low efficiency roll-off of this device is a result of extremely short PL lifetimes τ PL ~300 ns and high radiative decay rate constants k r ~3×10 6 s -1 of the Ir(III) TADF emitters.",
  "abstract_shown": true,
  "affiliations": [
    "Faculty of Chemistry, Silesian University of Technology, M. Strzody 9, Gliwice, Poland, 44-100",
    "Centre for Organic and Nanohybrid Electronics, Silesian University of Technology, Konarskiego 22B, Gliwice, Poland, 44-100",
    "Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw, Poland, 00-664",
    "Department of Physics, Durham University, South Road, Durham, United Kingdom, DH1 3LE"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Paulina H. Marek-Urban"
    },
    {
      "affs": [
        3
      ],
      "name": "Hector Miranda-Salinas"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Kinga Kępska"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Marilia Gabriela Belarmino Cabral"
    },
    {
      "affs": [
        0
      ],
      "name": "Karol Erfurt"
    },
    {
      "affs": [
        2
      ],
      "name": "Karolina Wrochna"
    },
    {
      "affs": [
        3
      ],
      "name": "Andrew P. Monkman"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Piotr Pander",
      "orcid": "0000-0003-4103-4154"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c1w3p4t6w48qm.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008378/v1",
  "fulltext_url": null,
  "id": "c1w3p4t6w48qm",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008378/v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2208|Organic Light-Emitting Diodes Research"
    ]
  ],
  "openalex": "W7211879770",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008378/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-06",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/c1w3p4t6w48qm.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.26434/chemrxiv.15008378",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008378/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "source:chemrxiv",
      "subfield": "general"
    }
  ],
  "title": "Harnessing TADF in iridium(III) complexes for nearly 20% external quantum efficiency in solution-processed OLEDs",
  "title_text": "Harnessing TADF in iridium(III) complexes for nearly 20% external quantum efficiency in solution-processed OLEDs",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:17Z",
  "url": "https://research.draconitic.com/paper/c1w3p4t6w48qm",
  "venue": "ChemRxiv",
  "versions": []
}