{
  "abstract": "Sequential thermal evaporation (sTE) is emerging as a solvent-free route to high-quality mid-bandgap perovskites, but its extension to mixed-halide wide-bandgap (WBG) and Sn-Pb narrow-bandgap (NBG) absorbers for all-perovskite tandem solar cells (TSCs) remains limited by an incomplete understanding of solid-state conversion. Here, using time-sliced ex situ analysis, we reveal divergent solid-state conversion mechanisms in sequentially evaporated WBG and NBG precursor stacks. In WBG stacks, formamidinium (FA)-containing species penetrate the inorganic template and Br/I redistribution precedes substantial three-dimensional perovskite formation. The photoactive phase then crystallizes from a chemically mixed reservoir, and absolute PbBr$_2$ thickness, rather than nominal PbBr$_2$/PbI$_2$ ratio, determines the final bandgap. In NBG stacks, by contrast, an early Pb-rich perovskite phase forms upon formamidinium iodide deposition, restricting further FA penetration into the buried SnI$_2$ precursor. Subsequent annealing promotes rapid lattice reorganization faster than Sn/Pb interdiffusion, leaving vertical compositional gradients. Guided by these insights, we develop sTE absorbers with bandgaps spanning 1.26-1.96 eV and demonstrate the first evaporated all-perovskite TSC, reaching a power conversion efficiency of 19.2%. Encapsulated tandems retain on average 80% of their initial efficiency after 1,200 h at 65 $^\\circ$C (ISOS-D-2). These results establish bandgap-specific control of solid-state conversion as a design principle for sequentially evaporated perovskite tandem photovoltaics.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.20326",
  "author_total": 11,
  "authors": [
    {
      "name": "Huagui Lai"
    },
    {
      "name": "Amber Wright"
    },
    {
      "name": "Nick Huber"
    },
    {
      "name": "Niels Uythoven"
    },
    {
      "name": "Federico De Giorgi"
    },
    {
      "name": "Jincheng Luo"
    },
    {
      "name": "Tristan Sachsenweger"
    },
    {
      "name": "Sunil B. Shivarudraiah"
    },
    {
      "name": "Chih-Jen Shih"
    },
    {
      "name": "Wolfgang Tress"
    },
    {
      "name": "Fan Fu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1j7z0ykd4z9qe.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.20326",
  "fulltext_url": null,
  "id": "1j7z0ykd4z9qe",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.20326",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "physics.app-ph"
    ],
    [
      "openalex",
      "2208|Perovskite Materials and Applications"
    ]
  ],
  "openalex": "W7213595328",
  "pdf_url": "https://arxiv.org/pdf/2609.20326",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1j7z0ykd4z9qe.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.20326",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.20326"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.app-ph",
      "subfield": "applied-instrumentation"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Divergent Solid-state Conversion Pathways in Evaporated All-perovskite Tandem Solar Cells",
  "title_text": "Divergent Solid-state Conversion Pathways in Evaporated All-perovskite Tandem Solar Cells",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/1j7z0ykd4z9qe",
  "venue": "arXiv",
  "versions": []
}