{
  "abstract": "Organic fluorescent nanoparticles (NPs) enable exceptional brightness through high dye loading, yet the fundamental relationship between local molecular organization and exciton dynamics remains elusive because short-range packing in densely packed assemblies is difficult to resolve using conventional structural characterization techniques. Here, femtosecond transient absorption spectroscopy reveals hidden short-range orientational order within globally disordered small-molecule ionic isolation lattice NPs (SMILES NPs) and establishes how this local organization governs exciton transport and fluorescence loss. Within locally ordered domains, fluorophore orientations are isotropically distributed within a two-dimensional plane perpendicular to the local stacking axis. Such local structural organization enables ultrafast exciton migration, followed by efficient energy funneling into non-emissive traps on a ~100 ps timescale, defining a kinetic window for exciton harvesting. Guided by this mechanistic insight, we introduce an emissive acceptor that captures excitons through sub-50 ps energy transfer, outcompeting trap-assisted quenching and producing binary SMILES NPs with a brightness per volume of 8700 M -1 cm -1 nm -3 , among the highest reported in the deep-red/near-infrared region. Collectively, this work establishes exciton dynamics as powerful probe of short-range molecular organization in dense molecular nanostructures and provides a molecular-packing-driven framework for controlling exciton transport and energy flow, offering general design principles for next-generation ultrabright emitters.",
  "abstract_shown": true,
  "affiliations": [
    "Nano-Science Center and Department of Chemistry",
    "University of Copenhagen",
    "ELI Beam lines Facility, The Extreme Light Infrastructure ERIC",
    "Department of Chemistry",
    "Indiana University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Simin Jiang"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Siyu Liu"
    },
    {
      "affs": [
        2
      ],
      "name": "Jakub Dostál"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Amar H. Flood"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Bo W. Laursen"
    },
    {
      "affs": [
        0,
        1,
        3,
        4
      ],
      "name": "Junsheng Chen",
      "orcid": "0000-0002-2934-8030"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1m902gz3cc1ba.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008882/v1",
  "fulltext_url": null,
  "id": "1m902gz3cc1ba",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008882/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",
      "2505|Luminescence and Fluorescent Materials"
    ]
  ],
  "openalex": "W7213329054",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008882/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-15",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/1m902gz3cc1ba.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15008882",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008882/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:2505|Luminescence and Fluorescent Materials",
      "subfield": "materials-polymers"
    }
  ],
  "title": "Order in Disorder: Exciton Dynamics Reveal Short-Range Molecular Packing in Small-Molecule Ionic Isolation Lattices Fluorescent Nanoparticles",
  "title_text": "Order in Disorder: Exciton Dynamics Reveal Short-Range Molecular Packing in Small-Molecule Ionic Isolation Lattices Fluorescent Nanoparticles",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/1m902gz3cc1ba",
  "venue": "ChemRxiv",
  "versions": []
}